thesis.lyx 235 KB

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  1. #LyX 2.3 created this file. For more info see http://www.lyx.org/
  2. \lyxformat 544
  3. \begin_document
  4. \begin_header
  5. \save_transient_properties true
  6. \origin unavailable
  7. \textclass extbook
  8. \begin_preamble
  9. % List all used files in log output
  10. \listfiles
  11. % Add a DRAFT watermark
  12. \usepackage{draftwatermark}
  13. \SetWatermarkLightness{0.97}
  14. \SetWatermarkScale{1}
  15. % Set up required header format
  16. \usepackage{fancyhdr}
  17. \pagestyle{fancy}
  18. \renewcommand{\headrulewidth}{0pt}
  19. \rhead{}
  20. \lhead{}
  21. \rfoot{}
  22. \lfoot{}
  23. \cfoot{\thepage} % Page number bottom center
  24. % Allow FloatBarrier command
  25. \usepackage{placeins}
  26. % Allow landscape pages
  27. \usepackage{pdflscape}
  28. % Allow doing things after the end of the current page
  29. % (to avoid landscape figures breaking up text)
  30. \usepackage{afterpage}
  31. % This one breaks subfigs so it's disabled
  32. % https://tex.stackexchange.com/questions/65680/automatically-bold-first-sentence-of-a-floats-caption
  33. \end_preamble
  34. \use_default_options true
  35. \begin_modules
  36. todonotes
  37. \end_modules
  38. \maintain_unincluded_children false
  39. \language english
  40. \language_package default
  41. \inputencoding utf8
  42. \fontencoding default
  43. \font_roman "default" "default"
  44. \font_sans "default" "default"
  45. \font_typewriter "default" "default"
  46. \font_math "auto" "auto"
  47. \font_default_family default
  48. \use_non_tex_fonts false
  49. \font_sc false
  50. \font_osf false
  51. \font_sf_scale 100 100
  52. \font_tt_scale 100 100
  53. \use_microtype false
  54. \use_dash_ligatures true
  55. \graphics default
  56. \default_output_format pdf4
  57. \output_sync 0
  58. \bibtex_command biber
  59. \index_command default
  60. \paperfontsize 12
  61. \spacing double
  62. \use_hyperref true
  63. \pdf_bookmarks true
  64. \pdf_bookmarksnumbered false
  65. \pdf_bookmarksopen false
  66. \pdf_bookmarksopenlevel 1
  67. \pdf_breaklinks false
  68. \pdf_pdfborder false
  69. \pdf_colorlinks false
  70. \pdf_backref false
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  96. \index Index
  97. \shortcut idx
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  120. \end_header
  121. \begin_body
  122. \begin_layout Title
  123. Bioinformatic analysis of complex, high-throughput genomic and epigenomic
  124. data in the context of immunology and transplant rejection
  125. \end_layout
  126. \begin_layout Author
  127. A thesis presented
  128. \begin_inset Newline newline
  129. \end_inset
  130. by
  131. \begin_inset Newline newline
  132. \end_inset
  133. Ryan C.
  134. Thompson
  135. \begin_inset Newline newline
  136. \end_inset
  137. to
  138. \begin_inset Newline newline
  139. \end_inset
  140. The Scripps Research Institute Graduate Program
  141. \begin_inset Newline newline
  142. \end_inset
  143. in partial fulfillment of the requirements for the degree of
  144. \begin_inset Newline newline
  145. \end_inset
  146. Doctor of Philosophy in the subject of Biology
  147. \begin_inset Newline newline
  148. \end_inset
  149. for
  150. \begin_inset Newline newline
  151. \end_inset
  152. The Scripps Research Institute
  153. \begin_inset Newline newline
  154. \end_inset
  155. La Jolla, California
  156. \end_layout
  157. \begin_layout Date
  158. October 2019
  159. \end_layout
  160. \begin_layout Standard
  161. [Copyright notice]
  162. \end_layout
  163. \begin_layout Standard
  164. [Thesis acceptance form]
  165. \end_layout
  166. \begin_layout Standard
  167. [Dedication]
  168. \end_layout
  169. \begin_layout Standard
  170. [Acknowledgements]
  171. \end_layout
  172. \begin_layout Standard
  173. \begin_inset CommandInset toc
  174. LatexCommand tableofcontents
  175. \end_inset
  176. \end_layout
  177. \begin_layout Standard
  178. \begin_inset FloatList table
  179. \end_inset
  180. \end_layout
  181. \begin_layout Standard
  182. \begin_inset FloatList figure
  183. \end_inset
  184. \end_layout
  185. \begin_layout Standard
  186. [List of Abbreviations]
  187. \end_layout
  188. \begin_layout Standard
  189. \begin_inset Flex TODO Note (inline)
  190. status open
  191. \begin_layout Plain Layout
  192. Look into auto-generated nomenclature list: https://wiki.lyx.org/Tips/Nomenclature
  193. \end_layout
  194. \end_inset
  195. \end_layout
  196. \begin_layout List of TODOs
  197. \end_layout
  198. \begin_layout Standard
  199. \begin_inset Flex TODO Note (inline)
  200. status open
  201. \begin_layout Plain Layout
  202. On final pass: Check all figures to make sure they fit on the page with
  203. their legends.
  204. \end_layout
  205. \end_inset
  206. \end_layout
  207. \begin_layout Chapter*
  208. Abstract
  209. \end_layout
  210. \begin_layout Standard
  211. \begin_inset Note Note
  212. status open
  213. \begin_layout Plain Layout
  214. It is included as an integral part of the thesis and should immediately
  215. precede the introduction.
  216. \end_layout
  217. \begin_layout Plain Layout
  218. Preparing your Abstract.
  219. Your abstract (a succinct description of your work) is limited to 350 words.
  220. UMI will shorten it if they must; please do not exceed the limit.
  221. \end_layout
  222. \begin_layout Itemize
  223. Include pertinent place names, names of persons (in full), and other proper
  224. nouns.
  225. These are useful in automated retrieval.
  226. \end_layout
  227. \begin_layout Itemize
  228. Display symbols, as well as foreign words and phrases, clearly and accurately.
  229. Include transliterations for characters other than Roman and Greek letters
  230. and Arabic numerals.
  231. Include accents and diacritical marks.
  232. \end_layout
  233. \begin_layout Itemize
  234. Do not include graphs, charts, tables, or illustrations in your abstract.
  235. \end_layout
  236. \end_inset
  237. \end_layout
  238. \begin_layout Chapter
  239. Introduction
  240. \end_layout
  241. \begin_layout Section
  242. Background & Significance
  243. \end_layout
  244. \begin_layout Subsection
  245. Biological motivation
  246. \end_layout
  247. \begin_layout Itemize
  248. Rejection is the major long-term threat to organ and tissue grafts
  249. \end_layout
  250. \begin_deeper
  251. \begin_layout Itemize
  252. Common mechanisms of rejection
  253. \end_layout
  254. \begin_layout Itemize
  255. Effective immune suppression requires monitoring for rejection and tuning
  256. \end_layout
  257. \begin_layout Itemize
  258. Current tests for rejection (tissue biopsy) are invasive and biased
  259. \end_layout
  260. \begin_layout Itemize
  261. A blood test based on microarrays would be less biased and invasive
  262. \end_layout
  263. \end_deeper
  264. \begin_layout Itemize
  265. Memory cells are resistant to immune suppression
  266. \end_layout
  267. \begin_deeper
  268. \begin_layout Itemize
  269. Mechanisms of resistance in memory cells are poorly understood
  270. \end_layout
  271. \begin_layout Itemize
  272. A better understanding of immune memory formation is needed
  273. \end_layout
  274. \end_deeper
  275. \begin_layout Itemize
  276. Mesenchymal stem cell infusion is a promising new treatment to prevent/delay
  277. rejection
  278. \end_layout
  279. \begin_deeper
  280. \begin_layout Itemize
  281. Demonstrated in mice, but not yet in primates
  282. \end_layout
  283. \begin_layout Itemize
  284. Mechanism currently unknown, but MSC are known to be immune modulatory
  285. \end_layout
  286. \end_deeper
  287. \begin_layout Subsection
  288. Overview of bioinformatic analysis methods
  289. \end_layout
  290. \begin_layout Standard
  291. An overview of all the methods used, including what problem they solve,
  292. what assumptions they make, and a basic description of how they work.
  293. \end_layout
  294. \begin_layout Itemize
  295. ChIP-seq Peak calling
  296. \end_layout
  297. \begin_deeper
  298. \begin_layout Itemize
  299. Cross-correlation analysis to determine fragment size
  300. \end_layout
  301. \begin_layout Itemize
  302. Broad vs narrow peaks
  303. \end_layout
  304. \begin_layout Itemize
  305. SICER for broad peaks
  306. \end_layout
  307. \begin_layout Itemize
  308. IDR for biologically reproducible peaks
  309. \end_layout
  310. \begin_layout Itemize
  311. csaw peak filtering guidelines for unbiased downstream analysis
  312. \end_layout
  313. \end_deeper
  314. \begin_layout Itemize
  315. Normalization is non-trivial and application-dependant
  316. \end_layout
  317. \begin_deeper
  318. \begin_layout Itemize
  319. Expression arrays: RMA & fRMA; why fRMA is needed
  320. \end_layout
  321. \begin_layout Itemize
  322. Methylation arrays: M-value transformation approximates normal data but
  323. induces heteroskedasticity
  324. \end_layout
  325. \begin_layout Itemize
  326. RNA-seq: normalize based on assumption that the average gene is not changing
  327. \end_layout
  328. \begin_layout Itemize
  329. ChIP-seq: complex with many considerations, dependent on experimental methods,
  330. biological system, and analysis goals
  331. \end_layout
  332. \end_deeper
  333. \begin_layout Itemize
  334. Limma: The standard linear modeling framework for genomics
  335. \end_layout
  336. \begin_deeper
  337. \begin_layout Itemize
  338. empirical Bayes variance modeling: limma's core feature
  339. \end_layout
  340. \begin_layout Itemize
  341. edgeR & DESeq2: Extend with negative bonomial GLM for RNA-seq and other
  342. count data
  343. \end_layout
  344. \begin_layout Itemize
  345. voom: Extend with precision weights to model mean-variance trend
  346. \end_layout
  347. \begin_layout Itemize
  348. arrayWeights and duplicateCorrelation to handle complex variance structures
  349. \end_layout
  350. \end_deeper
  351. \begin_layout Itemize
  352. sva and ComBat for batch correction
  353. \end_layout
  354. \begin_layout Itemize
  355. Factor analysis: PCA, MDS, MOFA
  356. \end_layout
  357. \begin_deeper
  358. \begin_layout Itemize
  359. Batch-corrected PCA is informative, but careful application is required
  360. to avoid bias
  361. \end_layout
  362. \end_deeper
  363. \begin_layout Itemize
  364. Gene set analysis: camera and SPIA
  365. \end_layout
  366. \begin_layout Section
  367. Innovation
  368. \end_layout
  369. \begin_layout Itemize
  370. MSC infusion to improve transplant outcomes (prevent/delay rejection)
  371. \end_layout
  372. \begin_deeper
  373. \begin_layout Itemize
  374. Characterize MSC response to interferon gamma
  375. \end_layout
  376. \begin_layout Itemize
  377. IFN-g is thought to stimulate their function
  378. \end_layout
  379. \begin_layout Itemize
  380. Test IFN-g treated MSC infusion as a therapy to delay graft rejection in
  381. cynomolgus monkeys
  382. \end_layout
  383. \begin_layout Itemize
  384. Monitor animals post-transplant using blood RNA-seq at serial time points
  385. \end_layout
  386. \end_deeper
  387. \begin_layout Itemize
  388. Investigate dynamics of histone marks in CD4 T-cell activation and memory
  389. \end_layout
  390. \begin_deeper
  391. \begin_layout Itemize
  392. Previous studies have looked at single snapshots of histone marks
  393. \end_layout
  394. \begin_layout Itemize
  395. Instead, look at changes in histone marks across activation and memory
  396. \end_layout
  397. \end_deeper
  398. \begin_layout Itemize
  399. High-throughput sequencing and microarray technologies
  400. \end_layout
  401. \begin_deeper
  402. \begin_layout Itemize
  403. Powerful methods for assaying gene expression and epigenetics across entire
  404. genomes
  405. \end_layout
  406. \begin_layout Itemize
  407. Proper analysis requires finding and exploiting systematic genome-wide trends
  408. \end_layout
  409. \end_deeper
  410. \begin_layout Chapter
  411. Reproducible genome-wide epigenetic analysis of H3K4 and H3K27 methylation
  412. in naive and memory CD4 T-cell activation
  413. \end_layout
  414. \begin_layout Standard
  415. \begin_inset Flex TODO Note (inline)
  416. status open
  417. \begin_layout Plain Layout
  418. Chapter author list: Me, Sarah, Dan
  419. \end_layout
  420. \end_inset
  421. \end_layout
  422. \begin_layout Standard
  423. \begin_inset Flex TODO Note (inline)
  424. status open
  425. \begin_layout Plain Layout
  426. Need better section titles throughout the chapter
  427. \end_layout
  428. \end_inset
  429. \end_layout
  430. \begin_layout Section
  431. Approach
  432. \end_layout
  433. \begin_layout Itemize
  434. CD4 T-cells are central to all adaptive immune responses and memory
  435. \end_layout
  436. \begin_layout Itemize
  437. H3K4 and H3K27 methylation are major epigenetic regulators of gene expression
  438. \end_layout
  439. \begin_layout Itemize
  440. Canonically, H3K4 is activating and H3K27 is inhibitory, but the reality
  441. is complex
  442. \end_layout
  443. \begin_layout Itemize
  444. Looking at these marks during CD4 activation and memory should reveal new
  445. mechanistic details
  446. \end_layout
  447. \begin_layout Itemize
  448. Test
  449. \begin_inset Quotes eld
  450. \end_inset
  451. poised promoter
  452. \begin_inset Quotes erd
  453. \end_inset
  454. hypothesis in which H3K4 and H3K27 are both methylated
  455. \end_layout
  456. \begin_layout Itemize
  457. Expand scope of analysis beyond simple promoter counts
  458. \end_layout
  459. \begin_deeper
  460. \begin_layout Itemize
  461. Analyze peaks genome-wide, including in intergenic regions
  462. \end_layout
  463. \begin_layout Itemize
  464. Analysis of coverage distribution shape within promoters, e.g.
  465. upstream vs downstream coverage
  466. \end_layout
  467. \end_deeper
  468. \begin_layout Section
  469. Methods
  470. \end_layout
  471. \begin_layout Standard
  472. A reproducible workflow
  473. \begin_inset CommandInset citation
  474. LatexCommand cite
  475. key "gh-cd4-csaw"
  476. literal "false"
  477. \end_inset
  478. was written to analyze the raw ChIP-seq and RNA-seq data from previous
  479. studies
  480. \begin_inset CommandInset citation
  481. LatexCommand cite
  482. key "LaMere2016,LaMere2017"
  483. literal "true"
  484. \end_inset
  485. .
  486. Briefly, this data consists of RNA-seq and ChIP-seq from CD4 T-cells cultured
  487. from 4 donors.
  488. From each donor, naive and memory CD4 T-cells were isolated separately.
  489. Then cultures of both cells were activated [how?], and samples were taken
  490. at 4 time points: Day 0 (pre-activation), Day 1 (early activation), Day
  491. 5 (peak activation), and Day 14 (post-activation).
  492. For each combination of cell type and time point, RNA was isolated, and
  493. ChIP-seq was performed for each of 3 histone marks: H3K4me2, H3K4me3, and
  494. H3K27me3.
  495. The ChIP-seq input was also sequenced for each sample.
  496. The result was 32 samples for each assay.
  497. \end_layout
  498. \begin_layout Standard
  499. Sequence reads were retrieved from the Sequence Read Archive (SRA)
  500. \begin_inset CommandInset citation
  501. LatexCommand cite
  502. key "Leinonen2011"
  503. literal "false"
  504. \end_inset
  505. .
  506. ChIP-seq (and input) reads were aligned to CRCh38 genome assembly using
  507. Bowtie 2
  508. \begin_inset CommandInset citation
  509. LatexCommand cite
  510. key "Langmead2012,Schneider2017,gh-hg38-ref"
  511. literal "false"
  512. \end_inset
  513. .
  514. Artifact regions were annotated using a custom implementation of the GreyListCh
  515. IP algorithm, and these
  516. \begin_inset Quotes eld
  517. \end_inset
  518. greylists
  519. \begin_inset Quotes erd
  520. \end_inset
  521. were merged with the ENCODE blacklist
  522. \begin_inset CommandInset citation
  523. LatexCommand cite
  524. key "greylistchip,Amemiya2019,Dunham2012"
  525. literal "false"
  526. \end_inset
  527. .
  528. Any read or peak overlapping one of these regions was regarded as artifactual
  529. and excluded from downstream analyses.
  530. \end_layout
  531. \begin_layout Standard
  532. Peaks are called using epic, an implementation of the SICER algorithm
  533. \begin_inset CommandInset citation
  534. LatexCommand cite
  535. key "Zang2009,gh-epic"
  536. literal "false"
  537. \end_inset
  538. .
  539. Peaks are also called separately using MACS, but MACS was determined to
  540. be a poor fit for the data, and these peak calls are not used further
  541. \begin_inset CommandInset citation
  542. LatexCommand cite
  543. key "Zhang2008"
  544. literal "false"
  545. \end_inset
  546. .
  547. \end_layout
  548. \begin_layout Itemize
  549. Re-analyze previously published CD4 ChIP-seq & RNA-seq data
  550. \end_layout
  551. \begin_deeper
  552. \begin_layout Itemize
  553. Completely reimplement analysis from scratch as a reproducible workflow
  554. \end_layout
  555. \begin_layout Itemize
  556. Use newly published methods & algorithms not available during the original
  557. analysis: SICER, csaw, MOFA
  558. \begin_inset CommandInset citation
  559. LatexCommand cite
  560. key "Argelaguet2018"
  561. literal "false"
  562. \end_inset
  563. , ComBat, sva, GREAT, and more
  564. \end_layout
  565. \end_deeper
  566. \begin_layout Itemize
  567. SICER, IDR, csaw, & GREAT to call ChIP-seq peaks genome-wide, perform differenti
  568. al abundance analysis, and relate those peaks to gene expression
  569. \end_layout
  570. \begin_layout Itemize
  571. Promoter counts in sliding windows around each gene's highest-expressed
  572. TSS to investigate coverage distribution within promoters
  573. \end_layout
  574. \begin_layout Subsection
  575. RNA-seq align+quant method comparison
  576. \end_layout
  577. \begin_layout Standard
  578. \align left
  579. \begin_inset Flex TODO Note (inline)
  580. status open
  581. \begin_layout Plain Layout
  582. Write a legend for Figure
  583. \begin_inset CommandInset ref
  584. LatexCommand ref
  585. reference "fig:RNA-norm-comp"
  586. plural "false"
  587. caps "false"
  588. noprefix "false"
  589. \end_inset
  590. \end_layout
  591. \end_inset
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  613. \begin_layout Plain Layout
  614. \begin_inset Caption Standard
  615. \begin_layout Plain Layout
  616. STAR quantification, Entrez vs Ensembl gene annotation
  617. \end_layout
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  637. \begin_inset Caption Standard
  638. \begin_layout Plain Layout
  639. Salmon+Shoal quantification, Entrez vs Ensembl gene annotation
  640. \end_layout
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  642. \end_layout
  643. \end_inset
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  662. \begin_layout Plain Layout
  663. STAR vs HISAT2 quantification, Ensembl gene annotation
  664. \end_layout
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  666. \end_layout
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  684. \begin_inset Caption Standard
  685. \begin_layout Plain Layout
  686. Salomn vs STAR quantification, Ensembl gene annotation
  687. \end_layout
  688. \end_inset
  689. \end_layout
  690. \end_inset
  691. \end_layout
  692. \begin_layout Plain Layout
  693. \align center
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  708. \begin_inset Caption Standard
  709. \begin_layout Plain Layout
  710. Salmon vs Kallisto quantification, Ensembl gene annotation
  711. \end_layout
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  713. \end_layout
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  728. \end_inset
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  730. \begin_layout Plain Layout
  731. \begin_inset Caption Standard
  732. \begin_layout Plain Layout
  733. Salmon+Shoal vs Salmon alone, Ensembl gene annotation
  734. \end_layout
  735. \end_inset
  736. \end_layout
  737. \end_inset
  738. \end_layout
  739. \begin_layout Plain Layout
  740. \begin_inset Caption Standard
  741. \begin_layout Plain Layout
  742. \begin_inset CommandInset label
  743. LatexCommand label
  744. name "fig:RNA-norm-comp"
  745. \end_inset
  746. RNA-seq comparisons
  747. \end_layout
  748. \end_inset
  749. \end_layout
  750. \end_inset
  751. \end_layout
  752. \begin_layout Itemize
  753. Ultimately selected shoal as quantification, Ensembl as annotation.
  754. Why? Running downstream analyses with all quant methods and both annotations
  755. showed very little practical difference, so choice was not terribly important.
  756. Prefer shoal due to theoretical advantages.
  757. To note in discussion: reproducible workflow made it easy to do this, enabling
  758. an informed decision.
  759. \end_layout
  760. \begin_layout Subsection
  761. RNA-seq has a large confounding batch effect
  762. \end_layout
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  768. \begin_layout Plain Layout
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  770. status open
  771. \begin_layout Plain Layout
  772. Just take the top row
  773. \end_layout
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  775. \end_layout
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  777. \align center
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  779. filename graphics/CD4-csaw/RNA-seq/weights-vs-covars-CROP.png
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  786. \begin_inset Caption Standard
  787. \begin_layout Plain Layout
  788. \series bold
  789. \begin_inset CommandInset label
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  793. RNA-seq sample weights, grouped by experimental and technical covariates.
  794. \end_layout
  795. \end_inset
  796. \end_layout
  797. \end_inset
  798. \end_layout
  799. \begin_layout Itemize
  800. Batch 1 is garbage quality.
  801. Analyses involving batch 1 samples are expected to yield poor statistical
  802. power.
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  832. Before batch correction
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  861. After batch correction with ComBat
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  875. PCoA plots of RNA-seq data showing effect of batch correction.
  876. \end_layout
  877. \end_inset
  878. \end_layout
  879. \end_inset
  880. \end_layout
  881. \begin_layout Itemize
  882. RNA-seq batch effect can be partially corrected, but still induces uncorrectable
  883. biases in downstream analysis
  884. \end_layout
  885. \begin_layout Subsection
  886. ChIP-seq blacklisting is important
  887. \end_layout
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  912. \begin_inset CommandInset label
  913. LatexCommand label
  914. name "fig:CCF-with-blacklist"
  915. \end_inset
  916. Cross-correlation plots with blacklisted reads removed
  917. \end_layout
  918. \end_inset
  919. \end_layout
  920. \end_inset
  921. \end_layout
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  931. filename graphics/CD4-csaw/csaw/CCF-plots-noBL-PAGE2-CROP.pdf
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  942. LatexCommand label
  943. name "fig:CCF-without-blacklist"
  944. \end_inset
  945. Cross-correlation plots without removing blacklisted reads
  946. \end_layout
  947. \end_inset
  948. \end_layout
  949. \end_inset
  950. \end_layout
  951. \begin_layout Plain Layout
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  956. LatexCommand label
  957. name "fig:CCF-master"
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  959. Strand cross-correlation plots for ChIP-seq data.
  960. \end_layout
  961. \end_inset
  962. \end_layout
  963. \end_inset
  964. \end_layout
  965. \begin_layout Subsection
  966. ChIP-seq peak calling
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  981. \begin_inset Graphics
  982. filename graphics/CD4-csaw/IDR/D4659vsD5053_epic-PAGE1-CROP.pdf
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  988. \begin_layout Plain Layout
  989. \begin_inset Caption Standard
  990. \begin_layout Plain Layout
  991. Peak ranks from SICER peak caller
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  993. \end_inset
  994. \end_layout
  995. \begin_layout Plain Layout
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  1013. \begin_layout Plain Layout
  1014. \begin_inset Caption Standard
  1015. \begin_layout Plain Layout
  1016. Peak ranks from MACS peak caller
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  1019. \end_layout
  1020. \end_inset
  1021. \end_layout
  1022. \begin_layout Plain Layout
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  1025. \series bold
  1026. \begin_inset CommandInset label
  1027. LatexCommand label
  1028. name "fig:IDR-rank-consist"
  1029. \end_inset
  1030. Irreproducible Discovery Rate rank consistency plots for H3K27me3.
  1031. \series default
  1032. Peaks are ranked by the scores assigned by the peak caller in each donor,
  1033. and then the ranks for two donors are plotted against each other.
  1034. Higher ranks are more significant (top right).
  1035. Peaks meeting various thresholds of reproducibility, measured by the irreproduc
  1036. ible discovery rate (IDR), are shaded accordingly.
  1037. [This could be explained better, or refer to the text.]
  1038. \end_layout
  1039. \end_inset
  1040. \end_layout
  1041. \begin_layout Plain Layout
  1042. \end_layout
  1043. \end_inset
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  1049. reference "fig:IDR-rank-consist"
  1050. plural "false"
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  1053. \end_inset
  1054. shows the IDR rank-consistency plots for peaks called in an arbitrarily-chosen
  1055. pair of donors.
  1056. when the peaks for each donor are ranked according to their scores, SICER
  1057. produces much more reproducible results between donors.
  1058. This is consistent with SICER's stated goal of identifying broad peaks,
  1059. in contrast to MACS, which is designed for identifying sharp peaks.
  1060. Based on this observation, the SICER peak calls were used for all downstream
  1061. analyses that involved ChIP-seq peaks.
  1062. \end_layout
  1063. \begin_layout Subsection
  1064. ChIP-seq normalization
  1065. \end_layout
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  1085. LatexCommand label
  1086. name "fig:MA-plot-bigbins"
  1087. \end_inset
  1088. MA plot of H3K4me2 read counts in 10kb bins for two arbitrary samples.
  1089. \end_layout
  1090. \end_inset
  1091. \end_layout
  1092. \end_inset
  1093. \end_layout
  1094. \begin_layout Subsection
  1095. ChIP-seq must be corrected for hidden confounding factors
  1096. \end_layout
  1097. \begin_layout Standard
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  1108. \align center
  1109. \begin_inset Graphics
  1110. filename graphics/CD4-csaw/ChIP-seq/H3K4me2-PCA-raw-CROP.png
  1111. lyxscale 25
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  1113. groupId pcoa-subfig
  1114. \end_inset
  1115. \end_layout
  1116. \begin_layout Plain Layout
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  1121. LatexCommand label
  1122. name "fig:PCoA-H3K4me2-bad"
  1123. \end_inset
  1124. H3K4me2, no correction
  1125. \end_layout
  1126. \end_inset
  1127. \end_layout
  1128. \end_inset
  1129. \begin_inset space \hfill{}
  1130. \end_inset
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  1138. filename graphics/CD4-csaw/ChIP-seq/H3K4me2-PCA-SVsub-CROP.png
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  1150. name "fig:PCoA-H3K4me2-good"
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  1152. H3K4me2, SVs subtracted
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  1177. LatexCommand label
  1178. name "fig:PCoA-H3K4me3-bad"
  1179. \end_inset
  1180. H3K4me3, no correction
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  1182. \end_inset
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  1201. \begin_inset Caption Standard
  1202. \begin_layout Plain Layout
  1203. \series bold
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  1205. LatexCommand label
  1206. name "fig:PCoA-H3K4me3-good"
  1207. \end_inset
  1208. H3K4me3, SVs subtracted
  1209. \end_layout
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  1222. filename graphics/CD4-csaw/ChIP-seq/H3K27me3-PCA-raw-CROP.png
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  1229. \begin_inset Caption Standard
  1230. \begin_layout Plain Layout
  1231. \series bold
  1232. \begin_inset CommandInset label
  1233. LatexCommand label
  1234. name "fig:PCoA-H3K27me3-bad"
  1235. \end_inset
  1236. H3K27me3, no correction
  1237. \end_layout
  1238. \end_inset
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  1241. \begin_inset space \hfill{}
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  1249. \begin_inset Graphics
  1250. filename graphics/CD4-csaw/ChIP-seq/H3K27me3-PCA-SVsub-CROP.png
  1251. lyxscale 25
  1252. width 45col%
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  1254. \end_inset
  1255. \end_layout
  1256. \begin_layout Plain Layout
  1257. \begin_inset Caption Standard
  1258. \begin_layout Plain Layout
  1259. \series bold
  1260. \begin_inset CommandInset label
  1261. LatexCommand label
  1262. name "fig:PCoA-H3K27me3-good"
  1263. \end_inset
  1264. H3K27me3, SVs subtracted
  1265. \end_layout
  1266. \end_inset
  1267. \end_layout
  1268. \end_inset
  1269. \end_layout
  1270. \begin_layout Plain Layout
  1271. \begin_inset Caption Standard
  1272. \begin_layout Plain Layout
  1273. \series bold
  1274. \begin_inset CommandInset label
  1275. LatexCommand label
  1276. name "fig:PCoA-ChIP"
  1277. \end_inset
  1278. PCoA plots of ChIP-seq sliding window data, before and after subtracting
  1279. surrogate variables (SVs).
  1280. \end_layout
  1281. \end_inset
  1282. \end_layout
  1283. \begin_layout Plain Layout
  1284. \end_layout
  1285. \end_inset
  1286. \end_layout
  1287. \begin_layout Itemize
  1288. Figures showing BCV plots with and without SVA for each histone mark?
  1289. \end_layout
  1290. \begin_layout Subsection
  1291. MOFA recovers biologically relevant variation from blind analysis by correlating
  1292. across datasets
  1293. \end_layout
  1294. \begin_layout Standard
  1295. \begin_inset ERT
  1296. status open
  1297. \begin_layout Plain Layout
  1298. \backslash
  1299. afterpage{
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  1309. wide false
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  1314. wide false
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  1318. \align center
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  1320. filename graphics/CD4-csaw/MOFA-varExplaiend-matrix-CROP.png
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  1328. \begin_layout Plain Layout
  1329. \series bold
  1330. \begin_inset CommandInset label
  1331. LatexCommand label
  1332. name "fig:mofa-varexplained"
  1333. \end_inset
  1334. Variance explained in each data set by each latent factor estimated by MOFA.
  1335. \series default
  1336. For each latent factor (LF) learned by MOFA, the variance explained by
  1337. that factor in each data set (
  1338. \begin_inset Quotes eld
  1339. \end_inset
  1340. view
  1341. \begin_inset Quotes erd
  1342. \end_inset
  1343. ) is shown by the shading of the cells in the lower section.
  1344. The upper section shows the total fraction of each data set's variance
  1345. that is explained by all LFs combined.
  1346. \end_layout
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  1348. \end_layout
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  1359. filename graphics/CD4-csaw/MOFA-LF-scatter-CROP.png
  1360. lyxscale 25
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  1367. \begin_layout Plain Layout
  1368. \series bold
  1369. \begin_inset CommandInset label
  1370. LatexCommand label
  1371. name "fig:mofa-lf-scatter"
  1372. \end_inset
  1373. Scatter plots of specific pairs of MOFA latent factors.
  1374. \series default
  1375. LFs 1, 4, and 5 explain substantial variation in all data sets, so they
  1376. are plotted against each other in order to reveal patterns of variation
  1377. that are shared across all data sets.
  1378. \end_layout
  1379. \end_inset
  1380. \end_layout
  1381. \end_inset
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  1385. \begin_layout Plain Layout
  1386. \series bold
  1387. \begin_inset CommandInset label
  1388. LatexCommand label
  1389. name "fig:MOFA-master"
  1390. \end_inset
  1391. MOFA latent factors separate technical confounders from
  1392. \end_layout
  1393. \end_inset
  1394. \end_layout
  1395. \end_inset
  1396. \end_layout
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  1398. \begin_inset ERT
  1399. status open
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  1405. }
  1406. \end_layout
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  1410. Figure
  1411. \begin_inset CommandInset ref
  1412. LatexCommand ref
  1413. reference "fig:mofa-varexplained"
  1414. plural "false"
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  1417. \end_inset
  1418. shows that LF1, 4, and 5 explain substantial var in all data sets
  1419. \end_layout
  1420. \begin_layout Itemize
  1421. Figure
  1422. \begin_inset CommandInset ref
  1423. LatexCommand ref
  1424. reference "fig:mofa-lf-scatter"
  1425. plural "false"
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  1428. \end_inset
  1429. shows that those same 3 LFs, (1, 4, & 5) also correlate best with the experimen
  1430. tal factors (cell type & time point)
  1431. \end_layout
  1432. \begin_layout Itemize
  1433. LF2 is clearly the RNA-seq batch effect
  1434. \end_layout
  1435. \begin_layout Standard
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  1450. \begin_inset Caption Standard
  1451. \begin_layout Plain Layout
  1452. \series bold
  1453. \begin_inset CommandInset label
  1454. LatexCommand label
  1455. name "fig:mofa-batchsub"
  1456. \end_inset
  1457. Result of RNA-seq batch-correction using MOFA latent factors
  1458. \end_layout
  1459. \end_inset
  1460. \end_layout
  1461. \end_inset
  1462. \end_layout
  1463. \begin_layout Itemize
  1464. Attempting to remove the effect of LF2 (Figure
  1465. \begin_inset CommandInset ref
  1466. LatexCommand ref
  1467. reference "fig:mofa-batchsub"
  1468. plural "false"
  1469. caps "false"
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  1471. \end_inset
  1472. ) results in batch correction comparable to ComBat (Figure
  1473. \begin_inset CommandInset ref
  1474. LatexCommand ref
  1475. reference "fig:RNA-PCA-ComBat-batchsub"
  1476. plural "false"
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  1478. noprefix "false"
  1479. \end_inset
  1480. )
  1481. \end_layout
  1482. \begin_layout Itemize
  1483. MOFA was able to do this batch subtraction without directly using the sample
  1484. labels (sample labels were used implicitly to select which factor to subtract)
  1485. \end_layout
  1486. \begin_layout Itemize
  1487. Similarity of results shows that batch correction can't get much better
  1488. than ComBat (despite ComBat ignoring time point)
  1489. \end_layout
  1490. \begin_layout Subsection
  1491. MOFA does some interesting stuff but is mostly confirmatory in this context
  1492. \end_layout
  1493. \begin_layout Standard
  1494. \begin_inset Flex TODO Note (inline)
  1495. status open
  1496. \begin_layout Plain Layout
  1497. MOFA should be a footnote to something else, not its own point
  1498. \end_layout
  1499. \end_inset
  1500. \end_layout
  1501. \begin_layout Standard
  1502. \begin_inset Flex TODO Note (inline)
  1503. status open
  1504. \begin_layout Plain Layout
  1505. Combine with previous subsection
  1506. \end_layout
  1507. \end_inset
  1508. \end_layout
  1509. \begin_layout Itemize
  1510. MOFA shows great promise for accelerating discovery of major biological
  1511. effects in multi-omics datasets
  1512. \end_layout
  1513. \begin_deeper
  1514. \begin_layout Itemize
  1515. MOFA successfully separates biologically relevant patterns of variation
  1516. from technical confounding factors without knowing the sample labels, by
  1517. finding latent factors that explain variation across multiple data sets.
  1518. \end_layout
  1519. \begin_layout Itemize
  1520. MOFA was added to this analysis late and played primarily a confirmatory
  1521. role, but it was able to confirm earlier conclusions with much less prior
  1522. information (no sample labels) and much less analyst effort/input
  1523. \end_layout
  1524. \begin_layout Itemize
  1525. Less input from analyst means less opportunity to introduce unwanted bias
  1526. into results
  1527. \end_layout
  1528. \begin_layout Itemize
  1529. MOFA confirmed that the already-implemented batch correction in the RNA-seq
  1530. data was already performing as well as possible given the limitations of
  1531. the data
  1532. \end_layout
  1533. \end_deeper
  1534. \begin_layout Section
  1535. Results
  1536. \end_layout
  1537. \begin_layout Standard
  1538. \begin_inset Note Note
  1539. status open
  1540. \begin_layout Plain Layout
  1541. Focus on what hypotheses were tested, then select figures that show how
  1542. those hypotheses were tested, even if the result is a negative.
  1543. \end_layout
  1544. \begin_layout Plain Layout
  1545. Not every interesting result needs to be in here.
  1546. Chapter should tell a story.
  1547. \end_layout
  1548. \end_inset
  1549. \end_layout
  1550. \begin_layout Standard
  1551. \begin_inset Flex TODO Note (inline)
  1552. status open
  1553. \begin_layout Plain Layout
  1554. Maybe reorder these sections to do RNA-seq, then ChIP-seq, then combined
  1555. analyses?
  1556. \end_layout
  1557. \end_inset
  1558. \end_layout
  1559. \begin_layout Subsection
  1560. H3K4 and H3K27 methylation occur in broad regions and are enriched near
  1561. promoters
  1562. \end_layout
  1563. \begin_layout Standard
  1564. \begin_inset Float table
  1565. wide false
  1566. sideways false
  1567. status open
  1568. \begin_layout Plain Layout
  1569. \align center
  1570. \begin_inset Flex TODO Note (inline)
  1571. status open
  1572. \begin_layout Plain Layout
  1573. Also get
  1574. \emph on
  1575. median
  1576. \emph default
  1577. peak width and maybe other quantiles (25%, 75%)
  1578. \end_layout
  1579. \end_inset
  1580. \end_layout
  1581. \begin_layout Plain Layout
  1582. \align center
  1583. \begin_inset Tabular
  1584. <lyxtabular version="3" rows="4" columns="5">
  1585. <features tabularvalignment="middle">
  1586. <column alignment="center" valignment="top">
  1587. <column alignment="center" valignment="top">
  1588. <column alignment="center" valignment="top">
  1589. <column alignment="center" valignment="top">
  1590. <column alignment="center" valignment="top">
  1591. <row>
  1592. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1593. \begin_inset Text
  1594. \begin_layout Plain Layout
  1595. Histone Mark
  1596. \end_layout
  1597. \end_inset
  1598. </cell>
  1599. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1600. \begin_inset Text
  1601. \begin_layout Plain Layout
  1602. # Peaks
  1603. \end_layout
  1604. \end_inset
  1605. </cell>
  1606. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1607. \begin_inset Text
  1608. \begin_layout Plain Layout
  1609. Mean peak width
  1610. \end_layout
  1611. \end_inset
  1612. </cell>
  1613. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1614. \begin_inset Text
  1615. \begin_layout Plain Layout
  1616. genome coverage
  1617. \end_layout
  1618. \end_inset
  1619. </cell>
  1620. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  1621. \begin_inset Text
  1622. \begin_layout Plain Layout
  1623. FRiP
  1624. \end_layout
  1625. \end_inset
  1626. </cell>
  1627. </row>
  1628. <row>
  1629. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1630. \begin_inset Text
  1631. \begin_layout Plain Layout
  1632. H3K4me2
  1633. \end_layout
  1634. \end_inset
  1635. </cell>
  1636. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1637. \begin_inset Text
  1638. \begin_layout Plain Layout
  1639. 14965
  1640. \end_layout
  1641. \end_inset
  1642. </cell>
  1643. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1644. \begin_inset Text
  1645. \begin_layout Plain Layout
  1646. 3970
  1647. \end_layout
  1648. \end_inset
  1649. </cell>
  1650. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1651. \begin_inset Text
  1652. \begin_layout Plain Layout
  1653. 1.92%
  1654. \end_layout
  1655. \end_inset
  1656. </cell>
  1657. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  1658. \begin_inset Text
  1659. \begin_layout Plain Layout
  1660. 14.2%
  1661. \end_layout
  1662. \end_inset
  1663. </cell>
  1664. </row>
  1665. <row>
  1666. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1667. \begin_inset Text
  1668. \begin_layout Plain Layout
  1669. H3K4me3
  1670. \end_layout
  1671. \end_inset
  1672. </cell>
  1673. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1674. \begin_inset Text
  1675. \begin_layout Plain Layout
  1676. 6163
  1677. \end_layout
  1678. \end_inset
  1679. </cell>
  1680. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1681. \begin_inset Text
  1682. \begin_layout Plain Layout
  1683. 2946
  1684. \end_layout
  1685. \end_inset
  1686. </cell>
  1687. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1688. \begin_inset Text
  1689. \begin_layout Plain Layout
  1690. 0.588%
  1691. \end_layout
  1692. \end_inset
  1693. </cell>
  1694. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  1695. \begin_inset Text
  1696. \begin_layout Plain Layout
  1697. 6.57%
  1698. \end_layout
  1699. \end_inset
  1700. </cell>
  1701. </row>
  1702. <row>
  1703. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1704. \begin_inset Text
  1705. \begin_layout Plain Layout
  1706. H3K27me3
  1707. \end_layout
  1708. \end_inset
  1709. </cell>
  1710. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1711. \begin_inset Text
  1712. \begin_layout Plain Layout
  1713. 18139
  1714. \end_layout
  1715. \end_inset
  1716. </cell>
  1717. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1718. \begin_inset Text
  1719. \begin_layout Plain Layout
  1720. 18967
  1721. \end_layout
  1722. \end_inset
  1723. </cell>
  1724. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1725. \begin_inset Text
  1726. \begin_layout Plain Layout
  1727. 11.1%
  1728. \end_layout
  1729. \end_inset
  1730. </cell>
  1731. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  1732. \begin_inset Text
  1733. \begin_layout Plain Layout
  1734. 22.5%
  1735. \end_layout
  1736. \end_inset
  1737. </cell>
  1738. </row>
  1739. </lyxtabular>
  1740. \end_inset
  1741. \end_layout
  1742. \begin_layout Plain Layout
  1743. \begin_inset Caption Standard
  1744. \begin_layout Plain Layout
  1745. \series bold
  1746. \begin_inset CommandInset label
  1747. LatexCommand label
  1748. name "tab:peak-calling-summary"
  1749. \end_inset
  1750. Peak-calling summary.
  1751. \series default
  1752. For each histone mark, the number of peaks called using SICER at an IDR
  1753. threshold of ???, the mean width of those peaks, the fraction of the genome
  1754. covered by peaks, and the fraction of reads in peaks (FRiP).
  1755. \end_layout
  1756. \end_inset
  1757. \end_layout
  1758. \end_inset
  1759. \end_layout
  1760. \begin_layout Standard
  1761. Table
  1762. \begin_inset CommandInset ref
  1763. LatexCommand ref
  1764. reference "tab:peak-calling-summary"
  1765. plural "false"
  1766. caps "false"
  1767. noprefix "false"
  1768. \end_inset
  1769. gives a summary of the peak calling statistics for each histone mark.
  1770. Consistent with previous observations [CITATION NEEDED], all 3 histone
  1771. marks occur in broad regions spanning many consecutive nucleosomes, rather
  1772. than in sharp peaks as would be expected for a transcription factor or
  1773. other molecule that binds to specific sites.
  1774. This conclusion is further supported by Figure
  1775. \begin_inset CommandInset ref
  1776. LatexCommand ref
  1777. reference "fig:CCF-with-blacklist"
  1778. plural "false"
  1779. caps "false"
  1780. noprefix "false"
  1781. \end_inset
  1782. , in which a clear nucleosome-sized periodicity is visible in the cross-correlat
  1783. ion value for each sample, indicating that each time a given mark is present
  1784. on one histone, it is also likely to be found on adjacent histones as well.
  1785. H3K27me3 enrichment in particular is substantially more broad than either
  1786. H3K4 mark, with a mean peak width of almost 19,000 bp.
  1787. This is also reflected in the periodicity observed in Figure
  1788. \begin_inset CommandInset ref
  1789. LatexCommand ref
  1790. reference "fig:CCF-with-blacklist"
  1791. plural "false"
  1792. caps "false"
  1793. noprefix "false"
  1794. \end_inset
  1795. , which remains strong much farther out for H3K27me3 than the other marks,
  1796. showing H3K27me3 especially tends to be found on long runs of consecutive
  1797. histones.
  1798. \end_layout
  1799. \begin_layout Standard
  1800. \begin_inset Float figure
  1801. wide false
  1802. sideways false
  1803. status open
  1804. \begin_layout Plain Layout
  1805. \begin_inset Flex TODO Note (inline)
  1806. status open
  1807. \begin_layout Plain Layout
  1808. Ensure this figure uses the peak calls from the new analysis.
  1809. \end_layout
  1810. \end_inset
  1811. \end_layout
  1812. \begin_layout Plain Layout
  1813. \begin_inset Flex TODO Note (inline)
  1814. status open
  1815. \begin_layout Plain Layout
  1816. Need a control: shuffle all peaks and repeat, N times.
  1817. Do real vs shuffled control both in a top/bottom arrangement.
  1818. \end_layout
  1819. \end_inset
  1820. \end_layout
  1821. \begin_layout Plain Layout
  1822. \begin_inset Flex TODO Note (inline)
  1823. status open
  1824. \begin_layout Plain Layout
  1825. Consider counting TSS inside peaks as negative number indicating how far
  1826. \emph on
  1827. inside
  1828. \emph default
  1829. the peak the TSS is (i.e.
  1830. distance to nearest non-peak area).
  1831. \end_layout
  1832. \end_inset
  1833. \end_layout
  1834. \begin_layout Plain Layout
  1835. \begin_inset Flex TODO Note (inline)
  1836. status open
  1837. \begin_layout Plain Layout
  1838. The H3K4 part of this figure is included in
  1839. \begin_inset CommandInset citation
  1840. LatexCommand cite
  1841. key "LaMere2016"
  1842. literal "false"
  1843. \end_inset
  1844. as Fig.
  1845. S2.
  1846. Do I need to do anything about that?
  1847. \end_layout
  1848. \end_inset
  1849. \end_layout
  1850. \begin_layout Plain Layout
  1851. \align center
  1852. \begin_inset Graphics
  1853. filename graphics/CD4-csaw/Promoter Peak Distance Profile-PAGE1-CROP.pdf
  1854. lyxscale 50
  1855. width 80col%
  1856. \end_inset
  1857. \end_layout
  1858. \begin_layout Plain Layout
  1859. \begin_inset Caption Standard
  1860. \begin_layout Plain Layout
  1861. \series bold
  1862. \begin_inset CommandInset label
  1863. LatexCommand label
  1864. name "fig:near-promoter-peak-enrich"
  1865. \end_inset
  1866. Enrichment of peaks in promoter neighborhoods.
  1867. \series default
  1868. This plot shows the distribution of distances from each annotated transcription
  1869. start site in the genome to the nearest called peak.
  1870. Each line represents one combination of histone mark, cell type, and time
  1871. point.
  1872. Distributions are smoothed using kernel density estimation [CITE?].
  1873. Transcription start sites that occur
  1874. \emph on
  1875. within
  1876. \emph default
  1877. peaks were excluded from this plot to avoid a large spike at zero that
  1878. would overshadow the rest of the distribution.
  1879. \end_layout
  1880. \end_inset
  1881. \end_layout
  1882. \end_inset
  1883. \end_layout
  1884. \begin_layout Standard
  1885. \begin_inset Float table
  1886. wide false
  1887. sideways false
  1888. status open
  1889. \begin_layout Plain Layout
  1890. \align center
  1891. \begin_inset Tabular
  1892. <lyxtabular version="3" rows="4" columns="2">
  1893. <features tabularvalignment="middle">
  1894. <column alignment="center" valignment="top">
  1895. <column alignment="center" valignment="top">
  1896. <row>
  1897. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1898. \begin_inset Text
  1899. \begin_layout Plain Layout
  1900. Histone mark
  1901. \end_layout
  1902. \end_inset
  1903. </cell>
  1904. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  1905. \begin_inset Text
  1906. \begin_layout Plain Layout
  1907. Effective promoter radius
  1908. \end_layout
  1909. \end_inset
  1910. </cell>
  1911. </row>
  1912. <row>
  1913. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1914. \begin_inset Text
  1915. \begin_layout Plain Layout
  1916. H3K4me2
  1917. \end_layout
  1918. \end_inset
  1919. </cell>
  1920. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  1921. \begin_inset Text
  1922. \begin_layout Plain Layout
  1923. 1 kb
  1924. \end_layout
  1925. \end_inset
  1926. </cell>
  1927. </row>
  1928. <row>
  1929. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  1930. \begin_inset Text
  1931. \begin_layout Plain Layout
  1932. H3K4me3
  1933. \end_layout
  1934. \end_inset
  1935. </cell>
  1936. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  1937. \begin_inset Text
  1938. \begin_layout Plain Layout
  1939. 1 kb
  1940. \end_layout
  1941. \end_inset
  1942. </cell>
  1943. </row>
  1944. <row>
  1945. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  1946. \begin_inset Text
  1947. \begin_layout Plain Layout
  1948. H3K27me3
  1949. \end_layout
  1950. \end_inset
  1951. </cell>
  1952. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  1953. \begin_inset Text
  1954. \begin_layout Plain Layout
  1955. 2.5 kb
  1956. \end_layout
  1957. \end_inset
  1958. </cell>
  1959. </row>
  1960. </lyxtabular>
  1961. \end_inset
  1962. \end_layout
  1963. \begin_layout Plain Layout
  1964. \begin_inset Caption Standard
  1965. \begin_layout Plain Layout
  1966. \series bold
  1967. \begin_inset CommandInset label
  1968. LatexCommand label
  1969. name "tab:effective-promoter-radius"
  1970. \end_inset
  1971. Effective promoter radius for each histone mark.
  1972. \series default
  1973. These values represent the approximate distance from transcription start
  1974. site positions within which an excess of peaks are found, as shown in Figure
  1975. \begin_inset CommandInset ref
  1976. LatexCommand ref
  1977. reference "fig:near-promoter-peak-enrich"
  1978. plural "false"
  1979. caps "false"
  1980. noprefix "false"
  1981. \end_inset
  1982. .
  1983. \end_layout
  1984. \end_inset
  1985. \end_layout
  1986. \begin_layout Plain Layout
  1987. \end_layout
  1988. \end_inset
  1989. \end_layout
  1990. \begin_layout Standard
  1991. \begin_inset Flex TODO Note (inline)
  1992. status open
  1993. \begin_layout Plain Layout
  1994. Problem: the effective promoter radius concept is an interesting result
  1995. on its own, hence its placement here.
  1996. However, it is also important in the methods section, which comes first.
  1997. What do? Refer forward to this section? Move this section to Methods?
  1998. \end_layout
  1999. \end_inset
  2000. \end_layout
  2001. \begin_layout Standard
  2002. All 3 histone marks tend to occur more often near promoter regions, as shown
  2003. in Figure
  2004. \begin_inset CommandInset ref
  2005. LatexCommand ref
  2006. reference "fig:near-promoter-peak-enrich"
  2007. plural "false"
  2008. caps "false"
  2009. noprefix "false"
  2010. \end_inset
  2011. .
  2012. The majority of each density distribution is flat, representing the background
  2013. density of peaks genome-wide.
  2014. Each distribution has a peak near zero, representing an enrichment of peaks
  2015. close transcription start site (TSS) positions relative to the remainder
  2016. of the genome.
  2017. Interestingly, the
  2018. \begin_inset Quotes eld
  2019. \end_inset
  2020. radius
  2021. \begin_inset Quotes erd
  2022. \end_inset
  2023. within which this enrichment occurs is not the same for every histone mark
  2024. (Table
  2025. \begin_inset CommandInset ref
  2026. LatexCommand ref
  2027. reference "tab:effective-promoter-radius"
  2028. plural "false"
  2029. caps "false"
  2030. noprefix "false"
  2031. \end_inset
  2032. ).
  2033. For H3K4me2 and H3K4me3, peaks are most enriched within 1
  2034. \begin_inset space ~
  2035. \end_inset
  2036. kbp of TSS positions, while for H3K27me3, enrichment is broader, extending
  2037. to 2.5
  2038. \begin_inset space ~
  2039. \end_inset
  2040. kbp.
  2041. These
  2042. \begin_inset Quotes eld
  2043. \end_inset
  2044. effective promoter radii
  2045. \begin_inset Quotes erd
  2046. \end_inset
  2047. were used to define the promoter regions for all further analyses.
  2048. \end_layout
  2049. \begin_layout Standard
  2050. \begin_inset Flex TODO Note (inline)
  2051. status open
  2052. \begin_layout Plain Layout
  2053. Clarify that radius depends on histone mark but
  2054. \emph on
  2055. not
  2056. \emph default
  2057. experimental condition.
  2058. \end_layout
  2059. \end_inset
  2060. \end_layout
  2061. \begin_layout Standard
  2062. \begin_inset Flex TODO Note (inline)
  2063. status open
  2064. \begin_layout Plain Layout
  2065. Consider also showing figure for distance to nearest peak center, and reference
  2066. median peak size once that is known.
  2067. \end_layout
  2068. \end_inset
  2069. \end_layout
  2070. \begin_layout Subsection
  2071. H3K4 and H3K27 promoter methylation has broadly the expected correlation
  2072. with gene expression
  2073. \end_layout
  2074. \begin_layout Standard
  2075. \begin_inset Flex TODO Note (inline)
  2076. status open
  2077. \begin_layout Plain Layout
  2078. This section can easily be cut, especially if I can't find those plots.
  2079. \end_layout
  2080. \end_inset
  2081. \end_layout
  2082. \begin_layout Itemize
  2083. H3K4 is correlated with higher expression, and H3K27 is correlated with
  2084. lower expression genome-wide
  2085. \end_layout
  2086. \begin_layout Standard
  2087. \begin_inset Flex TODO Note (inline)
  2088. status open
  2089. \begin_layout Plain Layout
  2090. Grr, gotta find these figures.
  2091. Maybe in the old analysis? At least one of these plots is definitely in
  2092. Sarah's paper.
  2093. \end_layout
  2094. \end_inset
  2095. \end_layout
  2096. \begin_layout Itemize
  2097. Figures showing these correlations: box/violin plots of expression distributions
  2098. with every combination of peak presence/absence in promoter
  2099. \end_layout
  2100. \begin_layout Itemize
  2101. Appropriate statistical tests showing significant differences in expected
  2102. directions
  2103. \end_layout
  2104. \begin_layout Subsection
  2105. RNA-seq and H3K4 methylation patterns in naive and memory show convergence
  2106. at day 14
  2107. \end_layout
  2108. \begin_layout Standard
  2109. \end_layout
  2110. \begin_layout Standard
  2111. \begin_inset ERT
  2112. status open
  2113. \begin_layout Plain Layout
  2114. \backslash
  2115. afterpage{
  2116. \end_layout
  2117. \begin_layout Plain Layout
  2118. \backslash
  2119. begin{landscape}
  2120. \end_layout
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  2453. Number of differentially modified promoters between naive and memory cells
  2454. at each time point after activation.
  2455. \series default
  2456. This table shows both the number of differentially modified promoters detected
  2457. at a 10% FDR threshold (left half), and the total number of differentially
  2458. modified promoters as estimated using the method of
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  2464. (right half).
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  2511. PCoA plot of H3K4me2 promoters, after subtracting surrogate variables
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  2620. Check up on figure refs in this paragraph
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  2633. shows the patterns of variation in all 3 histone marks in the promoter
  2634. regions of the genome using principal coordinate analysis.
  2635. All 3 marks show a noticeable convergence between the naive and memory
  2636. samples at day 14, visible as an overlapping of the day 14 groups on each
  2637. plot.
  2638. This is consistent with the counts of significantly differentially modified
  2639. promoters and estimates of the total numbers of differentially modified
  2640. promoters shown in Table
  2641. \begin_inset CommandInset ref
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  2644. plural "false"
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  2648. .
  2649. For all histone marks, evidence of differential modification between naive
  2650. and memory samples was detected at every time point except day 14.
  2651. The day 14 convergence pattern is also present in the RNA-seq data (Figure
  2652. \begin_inset CommandInset ref
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  2655. plural "false"
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  2659. ), albiet in the 2nd and 3rd principal coordinates, indicating that it is
  2660. not the most dominant pattern driving gene expression.
  2661. Taken together, the data show that promoter histone methylation for these
  2662. 3 histone marks and RNA expression for naive and memory cells are most
  2663. similar at day 14, the furthest time point after activation.
  2664. MOFA was also able to capture this day 14 convergence pattern in latent
  2665. factor 5 (Figure
  2666. \begin_inset CommandInset ref
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  2673. ), which accounts for shared variation across all 3 histone marks and the
  2674. RNA-seq data, confirming that this is a coordinated pattern across all
  2675. 4 data sets.
  2676. \end_layout
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  2678. Effect of promoter coverage upstream vs downstream of TSS
  2679. \end_layout
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  2684. For the figures in this section, the group labels are arbitrary, so if time
  2685. allows, it would be good to manually reorder them in a logical way, e.g.
  2686. most upstream to most downstream.
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  2749. \end_inset
  2750. \end_layout
  2751. \begin_layout Plain Layout
  2752. \begin_inset Caption Standard
  2753. \begin_layout Plain Layout
  2754. \series bold
  2755. \begin_inset CommandInset label
  2756. LatexCommand label
  2757. name "fig:H3K4me2-neighborhood-pca"
  2758. \end_inset
  2759. PCA of relative coverage depth, colored by K-means cluster membership.
  2760. \end_layout
  2761. \end_inset
  2762. \end_layout
  2763. \end_inset
  2764. \begin_inset space \hfill{}
  2765. \end_inset
  2766. \begin_inset Float figure
  2767. wide false
  2768. sideways false
  2769. status collapsed
  2770. \begin_layout Plain Layout
  2771. \align center
  2772. \begin_inset Graphics
  2773. filename graphics/CD4-csaw/ChIP-seq/H3K4me2-neighborhood-expression-CROP.png
  2774. lyxscale 25
  2775. width 30col%
  2776. groupId covprof-subfig
  2777. \end_inset
  2778. \end_layout
  2779. \begin_layout Plain Layout
  2780. \begin_inset Caption Standard
  2781. \begin_layout Plain Layout
  2782. \series bold
  2783. \begin_inset CommandInset label
  2784. LatexCommand label
  2785. name "fig:H3K4me2-neighborhood-expression"
  2786. \end_inset
  2787. Gene expression grouped by promoter coverage clusters.
  2788. \end_layout
  2789. \end_inset
  2790. \end_layout
  2791. \end_inset
  2792. \end_layout
  2793. \begin_layout Plain Layout
  2794. \begin_inset Caption Standard
  2795. \begin_layout Plain Layout
  2796. \series bold
  2797. K-means clustering of promoter H3K4me2 relative coverage depth in naive
  2798. day 0 samples.
  2799. \series default
  2800. H3K4me2 ChIP-seq reads were binned into 500-bp windows tiled across each
  2801. promoter from 5
  2802. \begin_inset space ~
  2803. \end_inset
  2804. kbp upstream to 5
  2805. \begin_inset space ~
  2806. \end_inset
  2807. kbp downstream, and the logCPM values were normalized within each promoter
  2808. to an average of 0, yielding relative coverage depths.
  2809. These were then grouped using K-means clustering with
  2810. \begin_inset Formula $K=6$
  2811. \end_inset
  2812. ,
  2813. \series bold
  2814. \series default
  2815. and the average bin values were plotted for each cluster (a).
  2816. The
  2817. \begin_inset Formula $x$
  2818. \end_inset
  2819. -axis is the genomic coordinate of each bin relative to the the transcription
  2820. start site, and the
  2821. \begin_inset Formula $y$
  2822. \end_inset
  2823. -axis is the mean relative coverage depth of that bin across all promoters
  2824. in the cluster.
  2825. Each line represents the average
  2826. \begin_inset Quotes eld
  2827. \end_inset
  2828. shape
  2829. \begin_inset Quotes erd
  2830. \end_inset
  2831. of the promoter coverage for promoters in that cluster.
  2832. PCA was performed on the same data, and the first two principal components
  2833. were plotted, coloring each point by its K-means cluster identity (b).
  2834. For each cluster, the distribution of gene expression values was plotted
  2835. (c).
  2836. \end_layout
  2837. \end_inset
  2838. \end_layout
  2839. \end_inset
  2840. \end_layout
  2841. \begin_layout Standard
  2842. \begin_inset Float figure
  2843. wide false
  2844. sideways false
  2845. status collapsed
  2846. \begin_layout Plain Layout
  2847. \align center
  2848. \begin_inset Float figure
  2849. wide false
  2850. sideways false
  2851. status collapsed
  2852. \begin_layout Plain Layout
  2853. \align center
  2854. \begin_inset Graphics
  2855. filename graphics/CD4-csaw/ChIP-seq/H3K27me3-neighborhood-clusters-CROP.png
  2856. lyxscale 25
  2857. width 30col%
  2858. groupId covprof-subfig
  2859. \end_inset
  2860. \end_layout
  2861. \begin_layout Plain Layout
  2862. \begin_inset Caption Standard
  2863. \begin_layout Plain Layout
  2864. \series bold
  2865. \begin_inset CommandInset label
  2866. LatexCommand label
  2867. name "fig:H3K27me3-neighborhood-clusters"
  2868. \end_inset
  2869. Average relative coverage for each bin in each cluster
  2870. \end_layout
  2871. \end_inset
  2872. \end_layout
  2873. \end_inset
  2874. \begin_inset space \hfill{}
  2875. \end_inset
  2876. \begin_inset Float figure
  2877. wide false
  2878. sideways false
  2879. status collapsed
  2880. \begin_layout Plain Layout
  2881. \align center
  2882. \begin_inset Graphics
  2883. filename graphics/CD4-csaw/ChIP-seq/H3K27me3-neighborhood-PCA-CROP.png
  2884. lyxscale 25
  2885. width 30col%
  2886. groupId covprof-subfig
  2887. \end_inset
  2888. \end_layout
  2889. \begin_layout Plain Layout
  2890. \begin_inset Caption Standard
  2891. \begin_layout Plain Layout
  2892. \series bold
  2893. \begin_inset CommandInset label
  2894. LatexCommand label
  2895. name "fig:H3K27me3-neighborhood-pca"
  2896. \end_inset
  2897. PCA of relative coverage depth, colored by K-means cluster membership.
  2898. \end_layout
  2899. \end_inset
  2900. \end_layout
  2901. \end_inset
  2902. \begin_inset space \hfill{}
  2903. \end_inset
  2904. \begin_inset Float figure
  2905. wide false
  2906. sideways false
  2907. status collapsed
  2908. \begin_layout Plain Layout
  2909. \align center
  2910. \begin_inset Graphics
  2911. filename graphics/CD4-csaw/ChIP-seq/H3K27me3-neighborhood-expression-CROP.png
  2912. lyxscale 25
  2913. width 30col%
  2914. groupId covprof-subfig
  2915. \end_inset
  2916. \end_layout
  2917. \begin_layout Plain Layout
  2918. \begin_inset Caption Standard
  2919. \begin_layout Plain Layout
  2920. \series bold
  2921. \begin_inset CommandInset label
  2922. LatexCommand label
  2923. name "fig:H3K27me3-neighborhood-expression"
  2924. \end_inset
  2925. Gene expression grouped by promoter coverage clusters.
  2926. \end_layout
  2927. \end_inset
  2928. \end_layout
  2929. \end_inset
  2930. \end_layout
  2931. \begin_layout Plain Layout
  2932. \begin_inset Caption Standard
  2933. \begin_layout Plain Layout
  2934. \series bold
  2935. K-means clustering of promoter H3K27me3 relative coverage depth in naive
  2936. day 0 samples.
  2937. \series default
  2938. H3K27me3 ChIP-seq reads were binned into 500-bp windows tiled across each
  2939. promoter from 5
  2940. \begin_inset space ~
  2941. \end_inset
  2942. kbp upstream to 5
  2943. \begin_inset space ~
  2944. \end_inset
  2945. kbp downstream, and the logCPM values were normalized within each promoter
  2946. to an average of 0, yielding relative coverage depths.
  2947. These were then grouped using K-means clustering with
  2948. \begin_inset Formula $K=6$
  2949. \end_inset
  2950. ,
  2951. \series bold
  2952. \series default
  2953. and the average bin values were plotted for each cluster (a).
  2954. The
  2955. \begin_inset Formula $x$
  2956. \end_inset
  2957. -axis is the genomic coordinate of each bin relative to the the transcription
  2958. start site, and the
  2959. \begin_inset Formula $y$
  2960. \end_inset
  2961. -axis is the mean relative coverage depth of that bin across all promoters
  2962. in the cluster.
  2963. Each line represents the average
  2964. \begin_inset Quotes eld
  2965. \end_inset
  2966. shape
  2967. \begin_inset Quotes erd
  2968. \end_inset
  2969. of the promoter coverage for promoters in that cluster.
  2970. PCA was performed on the same data, and the first two principal components
  2971. were plotted, coloring each point by its K-means cluster identity (b).
  2972. For each cluster, the distribution of gene expression values was plotted
  2973. (c).
  2974. \end_layout
  2975. \end_inset
  2976. \end_layout
  2977. \end_inset
  2978. \end_layout
  2979. \begin_layout Standard
  2980. \begin_inset ERT
  2981. status open
  2982. \begin_layout Plain Layout
  2983. \backslash
  2984. end{landscape}
  2985. \end_layout
  2986. \begin_layout Plain Layout
  2987. }
  2988. \end_layout
  2989. \end_inset
  2990. \end_layout
  2991. \begin_layout Itemize
  2992. H3K4me peaks seem to correlate with increased expression as long as they
  2993. are anywhere near the TSS
  2994. \end_layout
  2995. \begin_layout Itemize
  2996. H3K27me3 peaks can have different correlations to gene expression depending
  2997. on their position relative to TSS (e.g.
  2998. upstream vs downstream) Results consistent with
  2999. \begin_inset CommandInset citation
  3000. LatexCommand cite
  3001. key "Young2011"
  3002. literal "false"
  3003. \end_inset
  3004. \end_layout
  3005. \begin_layout Standard
  3006. \begin_inset Flex TODO Note (inline)
  3007. status open
  3008. \begin_layout Plain Layout
  3009. Show the figures where the negative result ended this line of inquiry
  3010. \end_layout
  3011. \end_inset
  3012. \end_layout
  3013. \begin_layout Section
  3014. Discussion
  3015. \end_layout
  3016. \begin_layout Subsection
  3017. Effective promoter radius
  3018. \end_layout
  3019. \begin_layout Itemize
  3020. "Promoter radius" is not constant and must be defined empirically for a
  3021. given data set.
  3022. Coverage within promoter radius has an expression correlation as well
  3023. \end_layout
  3024. \begin_layout Itemize
  3025. Further study required to demonstarte functional consequences of effective
  3026. promoter radius (e.g.
  3027. show diminished association with gene expression outside radius)
  3028. \end_layout
  3029. \begin_layout Subsection
  3030. Convergence
  3031. \end_layout
  3032. \begin_layout Standard
  3033. \begin_inset Float figure
  3034. wide false
  3035. sideways false
  3036. status collapsed
  3037. \begin_layout Plain Layout
  3038. \align center
  3039. \begin_inset Graphics
  3040. filename graphics/CD4-csaw/LaMere2016_fig8.pdf
  3041. lyxscale 50
  3042. width 100col%
  3043. groupId colwidth
  3044. \end_inset
  3045. \end_layout
  3046. \begin_layout Plain Layout
  3047. \begin_inset Caption Standard
  3048. \begin_layout Plain Layout
  3049. \series bold
  3050. LaMere 2016 Figure 8, reproduced with permission.
  3051. \end_layout
  3052. \end_inset
  3053. \end_layout
  3054. \end_inset
  3055. \end_layout
  3056. \begin_layout Standard
  3057. \begin_inset Flex TODO Note (inline)
  3058. status open
  3059. \begin_layout Plain Layout
  3060. Look up some more references for these histone marks being involved in memory
  3061. differentiation.
  3062. (Ask Sarah)
  3063. \end_layout
  3064. \end_inset
  3065. \end_layout
  3066. \begin_layout Itemize
  3067. Naive-to-memory convergence implies that naive cells are differentiating
  3068. into memory cells, and that gene expression and H3K4/K27 methylation are
  3069. involved in this differentiation
  3070. \end_layout
  3071. \begin_deeper
  3072. \begin_layout Itemize
  3073. Convergence is consistent with Lamere2016 fig 8
  3074. \begin_inset CommandInset citation
  3075. LatexCommand cite
  3076. key "LaMere2016"
  3077. literal "false"
  3078. \end_inset
  3079. (which was created without the benefit of SVA)
  3080. \end_layout
  3081. \begin_layout Itemize
  3082. H3K27me3, canonically regarded as a deactivating mark, seems to have a more
  3083. complex effect
  3084. \end_layout
  3085. \end_deeper
  3086. \begin_layout Subsection
  3087. Positional
  3088. \end_layout
  3089. \begin_layout Itemize
  3090. TSS positional coverage, hints of something interesting but no clear conclusions
  3091. \end_layout
  3092. \begin_layout Subsection
  3093. Workflow
  3094. \end_layout
  3095. \begin_layout Standard
  3096. \begin_inset ERT
  3097. status open
  3098. \begin_layout Plain Layout
  3099. \backslash
  3100. afterpage{
  3101. \end_layout
  3102. \begin_layout Plain Layout
  3103. \backslash
  3104. begin{landscape}
  3105. \end_layout
  3106. \end_inset
  3107. \end_layout
  3108. \begin_layout Standard
  3109. \begin_inset Float figure
  3110. wide false
  3111. sideways false
  3112. status open
  3113. \begin_layout Plain Layout
  3114. \align center
  3115. \begin_inset Graphics
  3116. filename graphics/CD4-csaw/rulegraphs/rulegraph-all.pdf
  3117. lyxscale 50
  3118. width 100col%
  3119. height 95theight%
  3120. \end_inset
  3121. \end_layout
  3122. \begin_layout Plain Layout
  3123. \begin_inset Caption Standard
  3124. \begin_layout Plain Layout
  3125. \begin_inset CommandInset label
  3126. LatexCommand label
  3127. name "fig:rulegraph"
  3128. \end_inset
  3129. \series bold
  3130. Dependency graph of steps in reproducible workflow
  3131. \end_layout
  3132. \end_inset
  3133. \end_layout
  3134. \end_inset
  3135. \end_layout
  3136. \begin_layout Standard
  3137. \begin_inset ERT
  3138. status open
  3139. \begin_layout Plain Layout
  3140. \backslash
  3141. end{landscape}
  3142. \end_layout
  3143. \begin_layout Plain Layout
  3144. }
  3145. \end_layout
  3146. \end_inset
  3147. \end_layout
  3148. \begin_layout Itemize
  3149. Discuss advantages of developing using a reproducible workflow
  3150. \end_layout
  3151. \begin_deeper
  3152. \begin_layout Itemize
  3153. Decision-making based on trying every option and running the workflow downstream
  3154. to see the effects
  3155. \end_layout
  3156. \end_deeper
  3157. \begin_layout Subsection
  3158. Data quality issues limit conclusions
  3159. \end_layout
  3160. \begin_layout Chapter
  3161. Improving array-based analyses of transplant rejection by optimizing data
  3162. preprocessing
  3163. \end_layout
  3164. \begin_layout Standard
  3165. \begin_inset Note Note
  3166. status open
  3167. \begin_layout Plain Layout
  3168. Chapter author list: Me, Sunil, Tom, Padma, Dan
  3169. \end_layout
  3170. \end_inset
  3171. \end_layout
  3172. \begin_layout Section
  3173. Approach
  3174. \end_layout
  3175. \begin_layout Subsection
  3176. Proper pre-processing is essential for array data
  3177. \end_layout
  3178. \begin_layout Standard
  3179. \begin_inset Flex TODO Note (inline)
  3180. status open
  3181. \begin_layout Plain Layout
  3182. This section could probably use some citations
  3183. \end_layout
  3184. \end_inset
  3185. \end_layout
  3186. \begin_layout Standard
  3187. Microarrays, bead arrays, and similar assays produce raw data in the form
  3188. of fluorescence intensity measurements, with the each intensity measurement
  3189. proportional to the abundance of some fluorescently-labelled target DNA
  3190. or RNA sequence that base pairs to a specific probe sequence.
  3191. However, these measurements for each probe are also affected my many technical
  3192. confounding factors, such as the concentration of target material, strength
  3193. of off-target binding, and the sensitivity of the imaging sensor.
  3194. Some array designs also use multiple probe sequences for each target.
  3195. Hence, extensive pre-processing of array data is necessary to normalize
  3196. out the effects of these technical factors and summarize the information
  3197. from multiple probes to arrive at a single usable estimate of abundance
  3198. or other relevant quantity, such as a ratio of two abundances, for each
  3199. target.
  3200. \end_layout
  3201. \begin_layout Standard
  3202. The choice of pre-processing algorithms used in the analysis of an array
  3203. data set can have a large effect on the results of that analysis.
  3204. However, despite their importance, these steps are often neglected or rushed
  3205. in order to get to the more scientifically interesting analysis steps involving
  3206. the actual biology of the system under study.
  3207. Hence, it is often possible to achieve substantial gains in statistical
  3208. power, model goodness-of-fit, or other relevant performance measures, by
  3209. checking the assumptions made by each preprocessing step and choosing specific
  3210. normalization methods tailored to the specific goals of the current analysis.
  3211. \end_layout
  3212. \begin_layout Subsection
  3213. Normalization for clinical microarray classifiers must be single-channel
  3214. \end_layout
  3215. \begin_layout Subsubsection
  3216. Standard normalization methods are unsuitable for clinical application
  3217. \end_layout
  3218. \begin_layout Standard
  3219. As the cost of performing microarray assays falls, there is increasing interest
  3220. in using genomic assays for diagnostic purposes, such as distinguishing
  3221. healthy transplants (TX) from transplants undergoing acute rejection (AR)
  3222. or acute dysfunction with no rejection (ADNR).
  3223. However, the the standard normalization algorithm used for microarray data,
  3224. Robust Multi-chip Average (RMA)
  3225. \begin_inset CommandInset citation
  3226. LatexCommand cite
  3227. key "Irizarry2003a"
  3228. literal "false"
  3229. \end_inset
  3230. , is not applicable in a clinical setting.
  3231. Two of the steps in RMA, quantile normalization and probe summarization
  3232. by median polish, depend on every array in the data set being normalized.
  3233. This means that adding or removing any arrays from a data set changes the
  3234. normalized values for all arrays, and data sets that have been normalized
  3235. separately cannot be compared to each other.
  3236. Hence, when using RMA, any arrays to be analyzed together must also be
  3237. normalized together, and the set of arrays included in the data set must
  3238. be held constant throughout an analysis.
  3239. \end_layout
  3240. \begin_layout Standard
  3241. These limitations present serious impediments to the use of arrays as a
  3242. diagnostic tool.
  3243. When training a classifier, the samples to be classified must not be involved
  3244. in any step of the training process, lest their inclusion bias the training
  3245. process.
  3246. Once a classifier is deployed in a clinical setting, the samples to be
  3247. classified will not even
  3248. \emph on
  3249. exist
  3250. \emph default
  3251. at the time of training, so including them would be impossible even if
  3252. it were statistically justifiable.
  3253. Therefore, any machine learning application for microarrays demands that
  3254. the normalized expression values computed for an array must depend only
  3255. on information contained within that array.
  3256. This would ensure that each array's normalization is independent of every
  3257. other array, and that arrays normalized separately can still be compared
  3258. to each other without bias.
  3259. Such a normalization is commonly referred to as
  3260. \begin_inset Quotes eld
  3261. \end_inset
  3262. single-channel normalization
  3263. \begin_inset Quotes erd
  3264. \end_inset
  3265. .
  3266. \end_layout
  3267. \begin_layout Subsubsection
  3268. Several strategies are available to meet clinical normalization requirements
  3269. \end_layout
  3270. \begin_layout Standard
  3271. Frozen RMA (fRMA) addresses these concerns by replacing the quantile normalizati
  3272. on and median polish with alternatives that do not introduce inter-array
  3273. dependence, allowing each array to be normalized independently of all others
  3274. \begin_inset CommandInset citation
  3275. LatexCommand cite
  3276. key "McCall2010"
  3277. literal "false"
  3278. \end_inset
  3279. .
  3280. Quantile normalization is performed against a pre-generated set of quantiles
  3281. learned from a collection of 850 publically available arrays sampled from
  3282. a wide variety of tissues in the Gene Expression Omnibus (GEO).
  3283. Each array's probe intensity distribution is normalized against these pre-gener
  3284. ated quantiles.
  3285. The median polish step is replaced with a robust weighted average of probe
  3286. intensities, using inverse variance weights learned from the same public
  3287. GEO data.
  3288. The result is a normalization that satisfies the requirements mentioned
  3289. above: each array is normalized independently of all others, and any two
  3290. normalized arrays can be compared directly to each other.
  3291. \end_layout
  3292. \begin_layout Standard
  3293. One important limitation of fRMA is that it requires a separate reference
  3294. data set from which to learn the parameters (reference quantiles and probe
  3295. weights) that will be used to normalize each array.
  3296. These parameters are specific to a given array platform, and pre-generated
  3297. parameters are only provided for the most common platforms, such as Affymetrix
  3298. hgu133plus2.
  3299. For a less common platform, such as hthgu133pluspm, is is necessary to
  3300. learn custom parameters from in-house data before fRMA can be used to normalize
  3301. samples on that platform
  3302. \begin_inset CommandInset citation
  3303. LatexCommand cite
  3304. key "McCall2011"
  3305. literal "false"
  3306. \end_inset
  3307. .
  3308. \end_layout
  3309. \begin_layout Standard
  3310. One other option is the aptly-named Single Channel Array Normalization (SCAN),
  3311. which adapts a normalization method originally designed for tiling arrays
  3312. \begin_inset CommandInset citation
  3313. LatexCommand cite
  3314. key "Piccolo2012"
  3315. literal "false"
  3316. \end_inset
  3317. .
  3318. SCAN is truly single-channel in that it does not require a set of normalization
  3319. paramters estimated from an external set of reference samples like fRMA
  3320. does.
  3321. \end_layout
  3322. \begin_layout Subsection
  3323. Heteroskedasticity must be accounted for in methylation array data
  3324. \end_layout
  3325. \begin_layout Subsubsection
  3326. Methylation array preprocessing induces heteroskedasticity
  3327. \end_layout
  3328. \begin_layout Standard
  3329. DNA methylation arrays are a relatively new kind of assay that uses microarrays
  3330. to measure the degree of methylation on cytosines in specific regions arrayed
  3331. across the genome.
  3332. First, bisulfite treatment converts all unmethylated cytosines to uracil
  3333. (which then become thymine after amplication) while leaving methylated
  3334. cytosines unaffected.
  3335. Then, each target region is interrogated with two probes: one binds to
  3336. the original genomic sequence and interrogates the level of methylated
  3337. DNA, and the other binds to the same sequence with all cytosines replaced
  3338. by thymidines and interrogates the level of unmethylated DNA.
  3339. \end_layout
  3340. \begin_layout Standard
  3341. \begin_inset Float figure
  3342. wide false
  3343. sideways false
  3344. status collapsed
  3345. \begin_layout Plain Layout
  3346. \align center
  3347. \begin_inset Graphics
  3348. filename graphics/methylvoom/sigmoid.pdf
  3349. lyxscale 50
  3350. width 100col%
  3351. groupId colwidth
  3352. \end_inset
  3353. \end_layout
  3354. \begin_layout Plain Layout
  3355. \begin_inset Caption Standard
  3356. \begin_layout Plain Layout
  3357. \begin_inset CommandInset label
  3358. LatexCommand label
  3359. name "fig:Sigmoid-beta-m-mapping"
  3360. \end_inset
  3361. \series bold
  3362. Sigmoid shape of the mapping between β and M values
  3363. \end_layout
  3364. \end_inset
  3365. \end_layout
  3366. \end_inset
  3367. \end_layout
  3368. \begin_layout Standard
  3369. After normalization, these two probe intensities are summarized in one of
  3370. two ways, each with advantages and disadvantages.
  3371. β
  3372. \series bold
  3373. \series default
  3374. values, interpreted as fraction of DNA copies methylated, range from 0 to
  3375. 1.
  3376. β
  3377. \series bold
  3378. \series default
  3379. values are conceptually easy to interpret, but the constrained range makes
  3380. them unsuitable for linear modeling, and their error distributions are
  3381. highly non-normal, which also frustrates linear modeling.
  3382. M-values, interpreted as the log ratio of methylated to unmethylated copies,
  3383. are computed by mapping the beta values from
  3384. \begin_inset Formula $[0,1]$
  3385. \end_inset
  3386. onto
  3387. \begin_inset Formula $(-\infty,+\infty)$
  3388. \end_inset
  3389. using a sigmoid curve (Figure
  3390. \begin_inset CommandInset ref
  3391. LatexCommand ref
  3392. reference "fig:Sigmoid-beta-m-mapping"
  3393. plural "false"
  3394. caps "false"
  3395. noprefix "false"
  3396. \end_inset
  3397. ).
  3398. This transformation results in values with better statistical perperties:
  3399. the unconstrained range is suitable for linear modeling, and the error
  3400. distributions are more normal.
  3401. Hence, most linear modeling and other statistical testing on methylation
  3402. arrays is performed using M-values.
  3403. \end_layout
  3404. \begin_layout Standard
  3405. However, the steep slope of the sigmoid transformation near 0 and 1 tends
  3406. to over-exaggerate small differences in β values near those extremes, which
  3407. in turn amplifies the error in those values, leading to a U-shaped trend
  3408. in the mean-variance curve: extreme values have higher variances than values
  3409. near the middle.
  3410. This mean-variance dependency must be accounted for when fitting the linear
  3411. model for differential methylation, or else the variance will be systematically
  3412. overestimated for probes with moderate M-values and underestimated for
  3413. probes with extreme M-values.
  3414. \end_layout
  3415. \begin_layout Subsubsection
  3416. The voom method for RNA-seq data can model M-value heteroskedasticity
  3417. \end_layout
  3418. \begin_layout Standard
  3419. RNA-seq read count data are also known to show heteroskedasticity, and the
  3420. voom method was developed for modeling this heteroskedasticity by estimating
  3421. the mean-variance trend in the data and using this trend to assign precision
  3422. weights to each observation
  3423. \begin_inset CommandInset citation
  3424. LatexCommand cite
  3425. key "Law2013"
  3426. literal "false"
  3427. \end_inset
  3428. .
  3429. While methylation array data are not derived from counts and have a very
  3430. different mean-variance relationship from that of typical RNA-seq data,
  3431. the voom method makes no specific assumptions on the shape of the mean-variance
  3432. relationship - it only assumes that the relationship is smooth enough to
  3433. model using a lowess curve.
  3434. Hence, the method is sufficiently general to model the mean-variance relationsh
  3435. ip in methylation array data.
  3436. However, the standard implementation of voom assumes that the input is
  3437. given in raw read counts, and it must be adapted to run on methylation
  3438. M-values.
  3439. \end_layout
  3440. \begin_layout Section
  3441. Methods
  3442. \end_layout
  3443. \begin_layout Subsection
  3444. Evaluation of classifier performance with different normalization methods
  3445. \end_layout
  3446. \begin_layout Standard
  3447. For testing different expression microarray normalizations, a data set of
  3448. 157 hgu133plus2 arrays was used, consisting of blood samples from kidney
  3449. transplant patients whose grafts had been graded as TX, AR, or ADNR via
  3450. biopsy and histology (46 TX, 69 AR, 42 ADNR)
  3451. \begin_inset CommandInset citation
  3452. LatexCommand cite
  3453. key "Kurian2014"
  3454. literal "true"
  3455. \end_inset
  3456. .
  3457. Additionally, an external validation set of 75 samples was gathered from
  3458. public GEO data (37 TX, 38 AR, no ADNR).
  3459. \end_layout
  3460. \begin_layout Standard
  3461. \begin_inset Flex TODO Note (inline)
  3462. status open
  3463. \begin_layout Plain Layout
  3464. Find appropriate GEO identifiers if possible.
  3465. Kurian 2014 says GSE15296, but this seems to be different data.
  3466. I also need to look up the GEO accession for the external validation set.
  3467. \end_layout
  3468. \end_inset
  3469. \end_layout
  3470. \begin_layout Standard
  3471. To evaluate the effect of each normalization on classifier performance,
  3472. the same classifier training and validation procedure was used after each
  3473. normalization method.
  3474. The PAM package was used to train a nearest shrunken centroid classifier
  3475. on the training set and select the appropriate threshold for centroid shrinking.
  3476. Then the trained classifier was used to predict the class probabilities
  3477. of each validation sample.
  3478. From these class probabilities, ROC curves and area-under-curve (AUC) values
  3479. were generated
  3480. \begin_inset CommandInset citation
  3481. LatexCommand cite
  3482. key "Turck2011"
  3483. literal "false"
  3484. \end_inset
  3485. .
  3486. Each normalization was tested on two different sets of training and validation
  3487. samples.
  3488. For internal validation, the 115 TX and AR arrays in the internal set were
  3489. split at random into two equal sized sets, one for training and one for
  3490. validation, each containing the same numbers of TX and AR samples as the
  3491. other set.
  3492. For external validation, the full set of 115 TX and AR samples were used
  3493. as a training set, and the 75 external TX and AR samples were used as the
  3494. validation set.
  3495. Thus, 2 ROC curves and AUC values were generated for each normalization
  3496. method: one internal and one external.
  3497. Because the external validation set contains no ADNR samples, only classificati
  3498. on of TX and AR samples was considered.
  3499. The ADNR samples were included during normalization but excluded from all
  3500. classifier training and validation.
  3501. This ensures that the performance on internal and external validation sets
  3502. is directly comparable, since both are performing the same task: distinguising
  3503. TX from AR.
  3504. \end_layout
  3505. \begin_layout Standard
  3506. \begin_inset Flex TODO Note (inline)
  3507. status open
  3508. \begin_layout Plain Layout
  3509. Summarize the get.best.threshold algorithm for PAM threshold selection, or
  3510. just put the code online?
  3511. \end_layout
  3512. \end_inset
  3513. \end_layout
  3514. \begin_layout Standard
  3515. Six different normalization strategies were evaluated.
  3516. First, 2 well-known non-single-channel normalization methods were considered:
  3517. RMA and dChip
  3518. \begin_inset CommandInset citation
  3519. LatexCommand cite
  3520. key "Li2001,Irizarry2003a"
  3521. literal "false"
  3522. \end_inset
  3523. .
  3524. Since RMA produces expression values on a log2 scale and dChip does not,
  3525. the values from dChip were log2 transformed after normalization.
  3526. Next, RMA and dChip followed by Global Rank-invariant Set Normalization
  3527. (GRSN) were tested
  3528. \begin_inset CommandInset citation
  3529. LatexCommand cite
  3530. key "Pelz2008"
  3531. literal "false"
  3532. \end_inset
  3533. .
  3534. Post-processing with GRSN does not turn RMA or dChip into single-channel
  3535. methods, but it may help mitigate batch effects and is therefore useful
  3536. as a benchmark.
  3537. Lastly, the two single-channel normalization methods, fRMA and SCAN, were
  3538. tested
  3539. \begin_inset CommandInset citation
  3540. LatexCommand cite
  3541. key "McCall2010,Piccolo2012"
  3542. literal "false"
  3543. \end_inset
  3544. .
  3545. When evaluting internal validation performance, only the 157 internal samples
  3546. were normalized; when evaluating external validation performance, all 157
  3547. internal samples and 75 external samples were normalized together.
  3548. \end_layout
  3549. \begin_layout Standard
  3550. For demonstrating the problem with separate normalization of training and
  3551. validation data, one additional normalization was performed: the internal
  3552. and external sets were each normalized separately using RMA, and the normalized
  3553. data for each set were combined into a single set with no further attempts
  3554. at normalizing between the two sets.
  3555. The represents approximately how RMA would have to be used in a clinical
  3556. setting, where the samples to be classified are not available at the time
  3557. the classifier is trained.
  3558. \end_layout
  3559. \begin_layout Subsection
  3560. Generating custom fRMA vectors for hthgu133pluspm array platform
  3561. \end_layout
  3562. \begin_layout Standard
  3563. In order to enable fRMA normalization for the hthgu133pluspm array platform,
  3564. custom fRMA normalization vectors were trained using the frmaTools package
  3565. \begin_inset CommandInset citation
  3566. LatexCommand cite
  3567. key "McCall2011"
  3568. literal "false"
  3569. \end_inset
  3570. .
  3571. Separate vectors were created for two types of samples: kidney graft biopsy
  3572. samples and blood samples from graft recipients.
  3573. For training, a 341 kidney biopsy samples from 2 data sets and 965 blood
  3574. samples from 5 data sets were used as the reference set.
  3575. Arrays were groups into batches based on unique combinations of sample
  3576. type (blood or biopsy), diagnosis (TX, AR, etc.), data set, and scan date.
  3577. Thus, each batch represents arrays of the same kind that were run together
  3578. on the same day.
  3579. For estimating the probe inverse variance weights, frmaTools requires equal-siz
  3580. ed batches, which means a batch size must be chosen, and then batches smaller
  3581. than that size must be ignored, while batches larger than the chosen size
  3582. must be downsampled.
  3583. This downsampling is performed randomly, so the sampling process is repeated
  3584. 5 times and the resulting normalizations are compared to each other.
  3585. \end_layout
  3586. \begin_layout Standard
  3587. To evaluate the consistency of the generated normalization vectors, the
  3588. 5 fRMA vector sets generated from 5 random batch samplings were each used
  3589. to normalize the same 20 randomly selected samples from each tissue.
  3590. Then the normalized expression values for each probe on each array were
  3591. compared across all normalizations.
  3592. Each fRMA normalization was also compared against the normalized expression
  3593. values obtained by normalizing the same 20 samples with ordinary RMA.
  3594. \end_layout
  3595. \begin_layout Subsection
  3596. Modeling methylation array M-value heteroskedasticy in linear models with
  3597. modified voom implementation
  3598. \end_layout
  3599. \begin_layout Standard
  3600. \begin_inset Flex TODO Note (inline)
  3601. status open
  3602. \begin_layout Plain Layout
  3603. Put code on Github and reference it.
  3604. \end_layout
  3605. \end_inset
  3606. \end_layout
  3607. \begin_layout Standard
  3608. To investigate the whether DNA methylation could be used to distinguish
  3609. between healthy and dysfunctional transplants, a data set of 78 Illumina
  3610. 450k methylation arrays from human kidney graft biopsies was analyzed for
  3611. differential metylation between 4 transplant statuses: healthy transplant
  3612. (TX), transplants undergoing acute rejection (AR), acute dysfunction with
  3613. no rejection (ADNR), and chronic allograpft nephropathy (CAN).
  3614. The data consisted of 33 TX, 9 AR, 8 ADNR, and 28 CAN samples.
  3615. The uneven group sizes are a result of taking the biopsy samples before
  3616. the eventual fate of the transplant was known.
  3617. Each sample was additionally annotated with a donor ID (anonymized), Sex,
  3618. Age, Ethnicity, Creatinine Level, and Diabetes diagnosois (all samples
  3619. in this data set came from patients with either Type 1 or Type 2 diabetes).
  3620. \end_layout
  3621. \begin_layout Standard
  3622. The intensity data were first normalized using subset-quantile within array
  3623. normalization (SWAN)
  3624. \begin_inset CommandInset citation
  3625. LatexCommand cite
  3626. key "Maksimovic2012"
  3627. literal "false"
  3628. \end_inset
  3629. , then converted to intensity ratios (beta values)
  3630. \begin_inset CommandInset citation
  3631. LatexCommand cite
  3632. key "Aryee2014"
  3633. literal "false"
  3634. \end_inset
  3635. .
  3636. Any probes binding to loci that overlapped annotated SNPs were dropped,
  3637. and the annotated sex of each sample was verified against the sex inferred
  3638. from the ratio of median probe intensities for the X and Y chromosomes.
  3639. Then, the ratios were transformed to M-values.
  3640. \end_layout
  3641. \begin_layout Standard
  3642. \begin_inset Float table
  3643. wide false
  3644. sideways false
  3645. status open
  3646. \begin_layout Plain Layout
  3647. \align center
  3648. \begin_inset Tabular
  3649. <lyxtabular version="3" rows="4" columns="6">
  3650. <features tabularvalignment="middle">
  3651. <column alignment="center" valignment="top">
  3652. <column alignment="center" valignment="top">
  3653. <column alignment="center" valignment="top">
  3654. <column alignment="center" valignment="top">
  3655. <column alignment="center" valignment="top">
  3656. <column alignment="center" valignment="top">
  3657. <row>
  3658. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3659. \begin_inset Text
  3660. \begin_layout Plain Layout
  3661. Analysis
  3662. \end_layout
  3663. \end_inset
  3664. </cell>
  3665. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3666. \begin_inset Text
  3667. \begin_layout Plain Layout
  3668. random effect
  3669. \end_layout
  3670. \end_inset
  3671. </cell>
  3672. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3673. \begin_inset Text
  3674. \begin_layout Plain Layout
  3675. eBayes
  3676. \end_layout
  3677. \end_inset
  3678. </cell>
  3679. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3680. \begin_inset Text
  3681. \begin_layout Plain Layout
  3682. SVA
  3683. \end_layout
  3684. \end_inset
  3685. </cell>
  3686. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3687. \begin_inset Text
  3688. \begin_layout Plain Layout
  3689. weights
  3690. \end_layout
  3691. \end_inset
  3692. </cell>
  3693. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  3694. \begin_inset Text
  3695. \begin_layout Plain Layout
  3696. voom
  3697. \end_layout
  3698. \end_inset
  3699. </cell>
  3700. </row>
  3701. <row>
  3702. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3703. \begin_inset Text
  3704. \begin_layout Plain Layout
  3705. A
  3706. \end_layout
  3707. \end_inset
  3708. </cell>
  3709. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3710. \begin_inset Text
  3711. \begin_layout Plain Layout
  3712. Yes
  3713. \end_layout
  3714. \end_inset
  3715. </cell>
  3716. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3717. \begin_inset Text
  3718. \begin_layout Plain Layout
  3719. Yes
  3720. \end_layout
  3721. \end_inset
  3722. </cell>
  3723. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3724. \begin_inset Text
  3725. \begin_layout Plain Layout
  3726. No
  3727. \end_layout
  3728. \end_inset
  3729. </cell>
  3730. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3731. \begin_inset Text
  3732. \begin_layout Plain Layout
  3733. No
  3734. \end_layout
  3735. \end_inset
  3736. </cell>
  3737. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  3738. \begin_inset Text
  3739. \begin_layout Plain Layout
  3740. No
  3741. \end_layout
  3742. \end_inset
  3743. </cell>
  3744. </row>
  3745. <row>
  3746. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3747. \begin_inset Text
  3748. \begin_layout Plain Layout
  3749. B
  3750. \end_layout
  3751. \end_inset
  3752. </cell>
  3753. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3754. \begin_inset Text
  3755. \begin_layout Plain Layout
  3756. Yes
  3757. \end_layout
  3758. \end_inset
  3759. </cell>
  3760. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3761. \begin_inset Text
  3762. \begin_layout Plain Layout
  3763. Yes
  3764. \end_layout
  3765. \end_inset
  3766. </cell>
  3767. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3768. \begin_inset Text
  3769. \begin_layout Plain Layout
  3770. Yes
  3771. \end_layout
  3772. \end_inset
  3773. </cell>
  3774. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  3775. \begin_inset Text
  3776. \begin_layout Plain Layout
  3777. Yes
  3778. \end_layout
  3779. \end_inset
  3780. </cell>
  3781. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  3782. \begin_inset Text
  3783. \begin_layout Plain Layout
  3784. No
  3785. \end_layout
  3786. \end_inset
  3787. </cell>
  3788. </row>
  3789. <row>
  3790. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3791. \begin_inset Text
  3792. \begin_layout Plain Layout
  3793. C
  3794. \end_layout
  3795. \end_inset
  3796. </cell>
  3797. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3798. \begin_inset Text
  3799. \begin_layout Plain Layout
  3800. Yes
  3801. \end_layout
  3802. \end_inset
  3803. </cell>
  3804. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3805. \begin_inset Text
  3806. \begin_layout Plain Layout
  3807. Yes
  3808. \end_layout
  3809. \end_inset
  3810. </cell>
  3811. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3812. \begin_inset Text
  3813. \begin_layout Plain Layout
  3814. Yes
  3815. \end_layout
  3816. \end_inset
  3817. </cell>
  3818. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  3819. \begin_inset Text
  3820. \begin_layout Plain Layout
  3821. Yes
  3822. \end_layout
  3823. \end_inset
  3824. </cell>
  3825. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  3826. \begin_inset Text
  3827. \begin_layout Plain Layout
  3828. Yes
  3829. \end_layout
  3830. \end_inset
  3831. </cell>
  3832. </row>
  3833. </lyxtabular>
  3834. \end_inset
  3835. \end_layout
  3836. \begin_layout Plain Layout
  3837. \begin_inset Caption Standard
  3838. \begin_layout Plain Layout
  3839. \series bold
  3840. \begin_inset CommandInset label
  3841. LatexCommand label
  3842. name "tab:Summary-of-meth-analysis"
  3843. \end_inset
  3844. Summary of analysis variants for methylation array data.
  3845. \series default
  3846. Each analysis included a different set of steps to adjust or account for
  3847. various systematic features of the data.
  3848. Random effect: The model included a random effect accounting for correlation
  3849. between samples from the same patient
  3850. \begin_inset CommandInset citation
  3851. LatexCommand cite
  3852. key "Smyth2005a"
  3853. literal "false"
  3854. \end_inset
  3855. ; eBayes: Empirical bayes squeezing of per-probe variances toward the mean-varia
  3856. nce trend
  3857. \begin_inset CommandInset citation
  3858. LatexCommand cite
  3859. key "Ritchie2015"
  3860. literal "false"
  3861. \end_inset
  3862. ; SVA: Surrogate variable analysis to account for unobserved confounders
  3863. \begin_inset CommandInset citation
  3864. LatexCommand cite
  3865. key "Leek2007"
  3866. literal "false"
  3867. \end_inset
  3868. ; Weights: Estimate sample weights to account for differences in sample
  3869. quality
  3870. \begin_inset CommandInset citation
  3871. LatexCommand cite
  3872. key "Liu2015,Ritchie2006"
  3873. literal "false"
  3874. \end_inset
  3875. ; voom: Use mean-variance trend to assign individual sample weights
  3876. \begin_inset CommandInset citation
  3877. LatexCommand cite
  3878. key "Law2013"
  3879. literal "false"
  3880. \end_inset
  3881. .
  3882. See the text for a more detailed explanation of each step.
  3883. \end_layout
  3884. \end_inset
  3885. \end_layout
  3886. \end_inset
  3887. \end_layout
  3888. \begin_layout Standard
  3889. From the M-values, a series of parallel analyses was performed, each adding
  3890. additional steps into the model fit to accomodate a feature of the data
  3891. (see Table
  3892. \begin_inset CommandInset ref
  3893. LatexCommand ref
  3894. reference "tab:Summary-of-meth-analysis"
  3895. plural "false"
  3896. caps "false"
  3897. noprefix "false"
  3898. \end_inset
  3899. ).
  3900. For analysis A, a
  3901. \begin_inset Quotes eld
  3902. \end_inset
  3903. basic
  3904. \begin_inset Quotes erd
  3905. \end_inset
  3906. linear modeling analysis was performed, compensating for known confounders
  3907. by including terms for the factor of interest (transplant status) as well
  3908. as the known biological confounders: sex, age, ethnicity, and diabetes.
  3909. Since some samples came from the same patients at different times, the
  3910. intra-patient correlation was modeled as a random effect, estimating a
  3911. shared correlation value across all probes
  3912. \begin_inset CommandInset citation
  3913. LatexCommand cite
  3914. key "Smyth2005a"
  3915. literal "false"
  3916. \end_inset
  3917. .
  3918. Then the linear model was fit, and the variance was modeled using empirical
  3919. Bayes squeezing toward the mean-variance trend
  3920. \begin_inset CommandInset citation
  3921. LatexCommand cite
  3922. key "Ritchie2015"
  3923. literal "false"
  3924. \end_inset
  3925. .
  3926. Finally, t-tests or F-tests were performed as appropriate for each test:
  3927. t-tests for single contrasts, and F-tests for multiple contrasts.
  3928. P-values were corrected for multiple testing using the Benjamini-Hochberg
  3929. procedure for FDR control
  3930. \begin_inset CommandInset citation
  3931. LatexCommand cite
  3932. key "Benjamini1995"
  3933. literal "false"
  3934. \end_inset
  3935. .
  3936. \end_layout
  3937. \begin_layout Standard
  3938. For the analysis B, surrogate variable analysis (SVA) was used to infer
  3939. additional unobserved sources of heterogeneity in the data
  3940. \begin_inset CommandInset citation
  3941. LatexCommand cite
  3942. key "Leek2007"
  3943. literal "false"
  3944. \end_inset
  3945. .
  3946. These surrogate variables were added to the design matrix before fitting
  3947. the linear model.
  3948. In addition, sample quality weights were estimated from the data and used
  3949. during linear modeling to down-weight the contribution of highly variable
  3950. arrays while increasing the weight to arrays with lower variability
  3951. \begin_inset CommandInset citation
  3952. LatexCommand cite
  3953. key "Ritchie2006"
  3954. literal "false"
  3955. \end_inset
  3956. .
  3957. The remainder of the analysis proceeded as in analysis A.
  3958. For analysis C, the voom method was adapted to run on methylation array
  3959. data and used to model and correct for the mean-variance trend using individual
  3960. observation weights
  3961. \begin_inset CommandInset citation
  3962. LatexCommand cite
  3963. key "Law2013"
  3964. literal "false"
  3965. \end_inset
  3966. , which were combined with the sample weights
  3967. \begin_inset CommandInset citation
  3968. LatexCommand cite
  3969. key "Liu2015,Ritchie2006"
  3970. literal "false"
  3971. \end_inset
  3972. .
  3973. Each time weights were used, they were estimated once before estimating
  3974. the random effect correlation value, and then the weights were re-estimated
  3975. taking the random effect into account.
  3976. The remainder of the analysis proceeded as in analysis B.
  3977. \end_layout
  3978. \begin_layout Section
  3979. Results
  3980. \end_layout
  3981. \begin_layout Standard
  3982. \begin_inset Flex TODO Note (inline)
  3983. status open
  3984. \begin_layout Plain Layout
  3985. Improve subsection titles in this section
  3986. \end_layout
  3987. \end_inset
  3988. \end_layout
  3989. \begin_layout Subsection
  3990. fRMA eliminates unwanted dependence of classifier training on normalization
  3991. strategy caused by RMA
  3992. \end_layout
  3993. \begin_layout Standard
  3994. \begin_inset Flex TODO Note (inline)
  3995. status open
  3996. \begin_layout Plain Layout
  3997. Write figure legends
  3998. \end_layout
  3999. \end_inset
  4000. \end_layout
  4001. \begin_layout Subsubsection
  4002. Separate normalization with RMA introduces unwanted biases in classification
  4003. \end_layout
  4004. \begin_layout Standard
  4005. \begin_inset Float figure
  4006. wide false
  4007. sideways false
  4008. status collapsed
  4009. \begin_layout Plain Layout
  4010. \align center
  4011. \begin_inset Graphics
  4012. filename graphics/PAM/predplot.pdf
  4013. lyxscale 50
  4014. width 100col%
  4015. groupId colwidth
  4016. \end_inset
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  4019. \begin_inset Caption Standard
  4020. \begin_layout Plain Layout
  4021. \begin_inset CommandInset label
  4022. LatexCommand label
  4023. name "fig:Classifier-probabilities-RMA"
  4024. \end_inset
  4025. \series bold
  4026. Classifier probabilities on validation samples when normalized with RMA
  4027. together vs.
  4028. separately.
  4029. \end_layout
  4030. \end_inset
  4031. \end_layout
  4032. \end_inset
  4033. \end_layout
  4034. \begin_layout Standard
  4035. To demonstrate the problem with non-single-channel normalization methods,
  4036. we considered the problem of training a classifier to distinguish TX from
  4037. AR using the samples from the internal set as training data, evaluating
  4038. performance on the external set.
  4039. First, training and evaluation were performed after normalizing all array
  4040. samples together as a single set using RMA, and second, the internal samples
  4041. were normalized separately from the external samples and the training and
  4042. evaluation were repeated.
  4043. For each sample in the validation set, the classifier probabilities from
  4044. both classifiers were plotted against each other (Fig.
  4045. \begin_inset CommandInset ref
  4046. LatexCommand ref
  4047. reference "fig:Classifier-probabilities-RMA"
  4048. plural "false"
  4049. caps "false"
  4050. noprefix "false"
  4051. \end_inset
  4052. ).
  4053. As expected, separate normalization biases the classifier probabilities,
  4054. resulting in several misclassifications.
  4055. In this case, the bias from separate normalization causes the classifier
  4056. to assign a lower probability of AR to every sample.
  4057. \end_layout
  4058. \begin_layout Subsubsection
  4059. fRMA and SCAN achieve maintain classification performance while eliminating
  4060. dependence on normalization strategy
  4061. \end_layout
  4062. \begin_layout Standard
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  4074. \begin_layout Plain Layout
  4075. \align center
  4076. \begin_inset Graphics
  4077. filename graphics/PAM/ROC-TXvsAR-internal.pdf
  4078. lyxscale 50
  4079. height 40theight%
  4080. groupId roc-pam
  4081. \end_inset
  4082. \end_layout
  4083. \begin_layout Plain Layout
  4084. \begin_inset Caption Standard
  4085. \begin_layout Plain Layout
  4086. \begin_inset CommandInset label
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  4088. name "fig:ROC-PAM-int"
  4089. \end_inset
  4090. ROC curves for PAM on internal validation data
  4091. \end_layout
  4092. \end_inset
  4093. \end_layout
  4094. \end_inset
  4095. \end_layout
  4096. \begin_layout Plain Layout
  4097. \align center
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  4099. placement tb
  4100. wide false
  4101. sideways false
  4102. status collapsed
  4103. \begin_layout Plain Layout
  4104. \align center
  4105. \begin_inset Graphics
  4106. filename graphics/PAM/ROC-TXvsAR-external.pdf
  4107. lyxscale 50
  4108. height 40theight%
  4109. groupId roc-pam
  4110. \end_inset
  4111. \end_layout
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  4117. name "fig:ROC-PAM-ext"
  4118. \end_inset
  4119. ROC curves for PAM on external validation data
  4120. \end_layout
  4121. \end_inset
  4122. \end_layout
  4123. \end_inset
  4124. \end_layout
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  4131. name "fig:ROC-PAM-main"
  4132. \end_inset
  4133. ROC curves for PAM using different normalization strategies
  4134. \end_layout
  4135. \end_inset
  4136. \end_layout
  4137. \end_inset
  4138. \end_layout
  4139. \begin_layout Standard
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  4286. \xout off
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  4289. \noun off
  4290. \color none
  4291. dChip
  4292. \end_layout
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  4295. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  4296. \begin_inset Text
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  4299. \end_layout
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  4317. 0.891
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  4356. \color none
  4357. RMA + GRSN
  4358. \end_layout
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  4361. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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  4382. \color none
  4383. 0.816
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  4402. 0.750
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  4418. \xout off
  4419. \uuline off
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  4421. \noun off
  4422. \color none
  4423. dChip + GRSN
  4424. \end_layout
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  4426. </cell>
  4427. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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  4449. 0.875
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  4468. 0.642
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  4484. \xout off
  4485. \uuline off
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  4488. \color none
  4489. fRMA
  4490. \end_layout
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  4493. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
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  4496. Yes
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  4515. 0.863
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  4517. \end_inset
  4518. </cell>
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  4537. </cell>
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  4539. <row>
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  4550. \xout off
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  4552. \uwave off
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  4554. \color none
  4555. SCAN
  4556. \end_layout
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  4562. Yes
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  4581. 0.853
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  4605. </lyxtabular>
  4606. \end_inset
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  4610. \begin_layout Plain Layout
  4611. \begin_inset CommandInset label
  4612. LatexCommand label
  4613. name "tab:AUC-PAM"
  4614. \end_inset
  4615. \series bold
  4616. AUC values for internal and external validation with 6 different normalization
  4617. strategies.
  4618. \series default
  4619. Only fRMA and SCAN are single-channel normalizations.
  4620. The other 4 normalizations are for comparison.
  4621. \end_layout
  4622. \end_inset
  4623. \end_layout
  4624. \end_inset
  4625. \end_layout
  4626. \begin_layout Standard
  4627. For internal validation, the 6 methods' AUC values ranged from 0.816 to 0.891,
  4628. as shown in Table
  4629. \begin_inset CommandInset ref
  4630. LatexCommand ref
  4631. reference "tab:AUC-PAM"
  4632. plural "false"
  4633. caps "false"
  4634. noprefix "false"
  4635. \end_inset
  4636. .
  4637. Among the non-single-channel normalizations, dChip outperformed RMA, while
  4638. GRSN reduced the AUC values for both dChip and RMA.
  4639. Both single-channel methods, fRMA and SCAN, slightly outperformed RMA,
  4640. with fRMA ahead of SCAN.
  4641. However, the difference between RMA and fRMA is still quite small.
  4642. Figure
  4643. \begin_inset CommandInset ref
  4644. LatexCommand ref
  4645. reference "fig:ROC-PAM-int"
  4646. plural "false"
  4647. caps "false"
  4648. noprefix "false"
  4649. \end_inset
  4650. shows that the ROC curves for RMA, dChip, and fRMA look very similar and
  4651. relatively smooth, while both GRSN curves and the curve for SCAN have a
  4652. more jagged appearance.
  4653. \end_layout
  4654. \begin_layout Standard
  4655. For external validation, as expected, all the AUC values are lower than
  4656. the internal validations, ranging from 0.642 to 0.750 (Table
  4657. \begin_inset CommandInset ref
  4658. LatexCommand ref
  4659. reference "tab:AUC-PAM"
  4660. plural "false"
  4661. caps "false"
  4662. noprefix "false"
  4663. \end_inset
  4664. ).
  4665. With or without GRSN, RMA shows its dominance over dChip in this more challengi
  4666. ng test.
  4667. Unlike in the internal validation, GRSN actually improves the classifier
  4668. performance for RMA, although it does not for dChip.
  4669. Once again, both single-channel methods perform about on par with RMA,
  4670. with fRMA performing slightly better and SCAN performing a bit worse.
  4671. Figure
  4672. \begin_inset CommandInset ref
  4673. LatexCommand ref
  4674. reference "fig:ROC-PAM-ext"
  4675. plural "false"
  4676. caps "false"
  4677. noprefix "false"
  4678. \end_inset
  4679. shows the ROC curves for the external validation test.
  4680. As expected, none of them are as clean-looking as the internal validation
  4681. ROC curves.
  4682. The curves for RMA, RMA+GRSN, and fRMA all look similar, while the other
  4683. curves look more divergent.
  4684. \end_layout
  4685. \begin_layout Subsection
  4686. fRMA with custom-generated vectors enables normalization on hthgu133pluspm
  4687. \end_layout
  4688. \begin_layout Standard
  4689. \begin_inset Float figure
  4690. wide false
  4691. sideways false
  4692. status collapsed
  4693. \begin_layout Plain Layout
  4694. \align center
  4695. \begin_inset Float figure
  4696. placement tb
  4697. wide false
  4698. sideways false
  4699. status collapsed
  4700. \begin_layout Plain Layout
  4701. \align center
  4702. \begin_inset Graphics
  4703. filename graphics/frma-pax-bx/batchsize_batches.pdf
  4704. lyxscale 50
  4705. height 35theight%
  4706. groupId frmatools-subfig
  4707. \end_inset
  4708. \end_layout
  4709. \begin_layout Plain Layout
  4710. \begin_inset Caption Standard
  4711. \begin_layout Plain Layout
  4712. \begin_inset CommandInset label
  4713. LatexCommand label
  4714. name "fig:batch-size-batches"
  4715. \end_inset
  4716. \series bold
  4717. Number of batches usable in fRMA probe weight learning as a function of
  4718. batch size.
  4719. \end_layout
  4720. \end_inset
  4721. \end_layout
  4722. \end_inset
  4723. \end_layout
  4724. \begin_layout Plain Layout
  4725. \align center
  4726. \begin_inset Float figure
  4727. placement tb
  4728. wide false
  4729. sideways false
  4730. status collapsed
  4731. \begin_layout Plain Layout
  4732. \align center
  4733. \begin_inset Graphics
  4734. filename graphics/frma-pax-bx/batchsize_samples.pdf
  4735. lyxscale 50
  4736. height 35theight%
  4737. groupId frmatools-subfig
  4738. \end_inset
  4739. \end_layout
  4740. \begin_layout Plain Layout
  4741. \begin_inset Caption Standard
  4742. \begin_layout Plain Layout
  4743. \begin_inset CommandInset label
  4744. LatexCommand label
  4745. name "fig:batch-size-samples"
  4746. \end_inset
  4747. \series bold
  4748. Number of samples usable in fRMA probe weight learning as a function of
  4749. batch size.
  4750. \end_layout
  4751. \end_inset
  4752. \end_layout
  4753. \end_inset
  4754. \end_layout
  4755. \begin_layout Plain Layout
  4756. \begin_inset Caption Standard
  4757. \begin_layout Plain Layout
  4758. \series bold
  4759. \begin_inset CommandInset label
  4760. LatexCommand label
  4761. name "fig:frmatools-batch-size"
  4762. \end_inset
  4763. Effect of batch size selection on number of batches and number of samples
  4764. included in fRMA probe weight learning.
  4765. \series default
  4766. For batch sizes ranging from 3 to 15, the number of batches (a) and samples
  4767. (b) included in probe weight training were plotted for biopsy (BX) and
  4768. blood (PAX) samples.
  4769. The selected batch size, 5, is marked with a dotted vertical line.
  4770. \end_layout
  4771. \end_inset
  4772. \end_layout
  4773. \end_inset
  4774. \end_layout
  4775. \begin_layout Standard
  4776. In order to enable use of fRMA to normalize hthgu133pluspm, a custom set
  4777. of fRMA vectors was created.
  4778. First, an appropriate batch size was chosen by looking at the number of
  4779. batches and number of samples included as a function of batch size (Figure
  4780. \begin_inset CommandInset ref
  4781. LatexCommand ref
  4782. reference "fig:frmatools-batch-size"
  4783. plural "false"
  4784. caps "false"
  4785. noprefix "false"
  4786. \end_inset
  4787. ).
  4788. For a given batch size, all batches with fewer samples that the chosen
  4789. size must be ignored during training, while larger batches must be randomly
  4790. downsampled to the chosen size.
  4791. Hence, the number of samples included for a given batch size equals the
  4792. batch size times the number of batches with at least that many samples.
  4793. From Figure
  4794. \begin_inset CommandInset ref
  4795. LatexCommand ref
  4796. reference "fig:batch-size-samples"
  4797. plural "false"
  4798. caps "false"
  4799. noprefix "false"
  4800. \end_inset
  4801. , it is apparent that that a batch size of 8 maximizes the number of samples
  4802. included in training.
  4803. Increasing the batch size beyond this causes too many smaller batches to
  4804. be excluded, reducing the total number of samples for both tissue types.
  4805. However, a batch size of 8 is not necessarily optimal.
  4806. The article introducing frmaTools concluded that it was highly advantageous
  4807. to use a smaller batch size in order to include more batches, even at the
  4808. expense of including fewer total samples in training
  4809. \begin_inset CommandInset citation
  4810. LatexCommand cite
  4811. key "McCall2011"
  4812. literal "false"
  4813. \end_inset
  4814. .
  4815. To strike an appropriate balance between more batches and more samples,
  4816. a batch size of 5 was chosen.
  4817. For both blood and biopsy samples, this increased the number of batches
  4818. included by 10, with only a modest reduction in the number of samples compared
  4819. to a batch size of 8.
  4820. With a batch size of 5, 26 batches of biopsy samples and 46 batches of
  4821. blood samples were available.
  4822. \end_layout
  4823. \begin_layout Standard
  4824. \begin_inset Float figure
  4825. wide false
  4826. sideways false
  4827. status open
  4828. \begin_layout Plain Layout
  4829. \begin_inset Float figure
  4830. wide false
  4831. sideways false
  4832. status collapsed
  4833. \begin_layout Plain Layout
  4834. \align center
  4835. \begin_inset Graphics
  4836. filename graphics/frma-pax-bx/M-BX-violin.pdf
  4837. lyxscale 40
  4838. width 45col%
  4839. groupId m-violin
  4840. \end_inset
  4841. \end_layout
  4842. \begin_layout Plain Layout
  4843. \begin_inset Caption Standard
  4844. \begin_layout Plain Layout
  4845. \begin_inset CommandInset label
  4846. LatexCommand label
  4847. name "fig:m-bx-violin"
  4848. \end_inset
  4849. \series bold
  4850. Violin plot of inter-normalization log ratios for biopsy samples.
  4851. \end_layout
  4852. \end_inset
  4853. \end_layout
  4854. \end_inset
  4855. \begin_inset space \hfill{}
  4856. \end_inset
  4857. \begin_inset Float figure
  4858. wide false
  4859. sideways false
  4860. status collapsed
  4861. \begin_layout Plain Layout
  4862. \align center
  4863. \begin_inset Graphics
  4864. filename graphics/frma-pax-bx/M-PAX-violin.pdf
  4865. lyxscale 40
  4866. width 45col%
  4867. groupId m-violin
  4868. \end_inset
  4869. \end_layout
  4870. \begin_layout Plain Layout
  4871. \begin_inset Caption Standard
  4872. \begin_layout Plain Layout
  4873. \begin_inset CommandInset label
  4874. LatexCommand label
  4875. name "fig:m-pax-violin"
  4876. \end_inset
  4877. \series bold
  4878. Violin plot of inter-normalization log ratios for blood samples.
  4879. \end_layout
  4880. \end_inset
  4881. \end_layout
  4882. \end_inset
  4883. \end_layout
  4884. \begin_layout Plain Layout
  4885. \begin_inset Caption Standard
  4886. \begin_layout Plain Layout
  4887. \series bold
  4888. Violin plot of log ratios between normalizations for 20 biopsy samples.
  4889. \series default
  4890. Each of 20 randomly selected samples was normalized with RMA and with 5
  4891. different sets of fRMA vectors.
  4892. The distribution of log ratios between normalized expression values, aggregated
  4893. across all 20 arrays, was plotted for each pair of normalizations.
  4894. \end_layout
  4895. \end_inset
  4896. \end_layout
  4897. \end_inset
  4898. \end_layout
  4899. \begin_layout Standard
  4900. Since fRMA training requires equal-size batches, larger batches are downsampled
  4901. randomly.
  4902. This introduces a nondeterministic step in the generation of normalization
  4903. vectors.
  4904. To show that this randomness does not substantially change the outcome,
  4905. the random downsampling and subsequent vector learning was repeated 5 times,
  4906. with a different random seed each time.
  4907. 20 samples were selected at random as a test set and normalized with each
  4908. of the 5 sets of fRMA normalization vectors as well as ordinary RMA, and
  4909. the normalized expression values were compared across normalizations.
  4910. Figure
  4911. \begin_inset CommandInset ref
  4912. LatexCommand ref
  4913. reference "fig:m-bx-violin"
  4914. plural "false"
  4915. caps "false"
  4916. noprefix "false"
  4917. \end_inset
  4918. shows a summary of these comparisons for biopsy samples.
  4919. Comparing RMA to each of the 5 fRMA normalizations, the distribution of
  4920. log ratios is somewhat wide, indicating that the normalizations disagree
  4921. on the expression values of a fair number of probe sets.
  4922. In contrast, comparisons of fRMA against fRMA, the vast mojority of probe
  4923. sets have very small log ratios, indicating a very high agreement between
  4924. the normalized values generated by the two normalizations.
  4925. This shows that the fRMA normalization's behavior is not very sensitive
  4926. to the random downsampling of larger batches during training.
  4927. \end_layout
  4928. \begin_layout Standard
  4929. \begin_inset Float figure
  4930. wide false
  4931. sideways false
  4932. status open
  4933. \begin_layout Plain Layout
  4934. \align center
  4935. \begin_inset Float figure
  4936. wide false
  4937. sideways false
  4938. status collapsed
  4939. \begin_layout Plain Layout
  4940. \align center
  4941. \begin_inset Graphics
  4942. filename graphics/frma-pax-bx/MA-BX-RMA.fRMA-RASTER.png
  4943. lyxscale 10
  4944. width 45col%
  4945. groupId ma-frma
  4946. \end_inset
  4947. \end_layout
  4948. \begin_layout Plain Layout
  4949. \begin_inset Caption Standard
  4950. \begin_layout Plain Layout
  4951. \begin_inset CommandInset label
  4952. LatexCommand label
  4953. name "fig:ma-bx-rma-frma"
  4954. \end_inset
  4955. \series bold
  4956. RMA vs.
  4957. fRMA for biopsy samples.
  4958. \end_layout
  4959. \end_inset
  4960. \end_layout
  4961. \end_inset
  4962. \begin_inset space \hfill{}
  4963. \end_inset
  4964. \begin_inset Float figure
  4965. wide false
  4966. sideways false
  4967. status collapsed
  4968. \begin_layout Plain Layout
  4969. \align center
  4970. \begin_inset Graphics
  4971. filename graphics/frma-pax-bx/MA-BX-fRMA.fRMA-RASTER.png
  4972. lyxscale 10
  4973. width 45col%
  4974. groupId ma-frma
  4975. \end_inset
  4976. \end_layout
  4977. \begin_layout Plain Layout
  4978. \begin_inset Caption Standard
  4979. \begin_layout Plain Layout
  4980. \begin_inset CommandInset label
  4981. LatexCommand label
  4982. name "fig:ma-bx-frma-frma"
  4983. \end_inset
  4984. \series bold
  4985. fRMA vs fRMA for biopsy samples.
  4986. \series default
  4987. Two different fRMA normalizations using vectors from two different batch
  4988. samplings were compared.
  4989. \end_layout
  4990. \end_inset
  4991. \end_layout
  4992. \end_inset
  4993. \end_layout
  4994. \begin_layout Plain Layout
  4995. \align center
  4996. \begin_inset Float figure
  4997. wide false
  4998. sideways false
  4999. status collapsed
  5000. \begin_layout Plain Layout
  5001. \align center
  5002. \begin_inset Graphics
  5003. filename graphics/frma-pax-bx/MA-PAX-RMA.fRMA-RASTER.png
  5004. lyxscale 10
  5005. width 45col%
  5006. groupId ma-frma
  5007. \end_inset
  5008. \end_layout
  5009. \begin_layout Plain Layout
  5010. \begin_inset Caption Standard
  5011. \begin_layout Plain Layout
  5012. \begin_inset CommandInset label
  5013. LatexCommand label
  5014. name "fig:MA-PAX-rma-frma"
  5015. \end_inset
  5016. \series bold
  5017. RMA vs.
  5018. fRMA for blood samples.
  5019. \end_layout
  5020. \end_inset
  5021. \end_layout
  5022. \end_inset
  5023. \begin_inset space \hfill{}
  5024. \end_inset
  5025. \begin_inset Float figure
  5026. wide false
  5027. sideways false
  5028. status collapsed
  5029. \begin_layout Plain Layout
  5030. \align center
  5031. \begin_inset Graphics
  5032. filename graphics/frma-pax-bx/MA-PAX-fRMA.fRMA-RASTER.png
  5033. lyxscale 10
  5034. width 45col%
  5035. groupId ma-frma
  5036. \end_inset
  5037. \end_layout
  5038. \begin_layout Plain Layout
  5039. \begin_inset Caption Standard
  5040. \begin_layout Plain Layout
  5041. \begin_inset CommandInset label
  5042. LatexCommand label
  5043. name "fig:MA-PAX-frma-frma"
  5044. \end_inset
  5045. \series bold
  5046. fRMA vs fRMA for blood samples.
  5047. \series default
  5048. Two different fRMA normalizations using vectors from two different batch
  5049. samplings were compared.
  5050. \end_layout
  5051. \end_inset
  5052. \end_layout
  5053. \end_inset
  5054. \end_layout
  5055. \begin_layout Plain Layout
  5056. \begin_inset Caption Standard
  5057. \begin_layout Plain Layout
  5058. \series bold
  5059. \begin_inset CommandInset label
  5060. LatexCommand label
  5061. name "fig:Representative-MA-plots"
  5062. \end_inset
  5063. Representative MA plots comparing RMA and custom fRMA normalizations.
  5064. \series default
  5065. For each plot, 20 samples were normalized using 2 different normalizations,
  5066. and then averages and log ratios were computed between the two different
  5067. normalizations for every probe.
  5068. Density of points is represented by darkness of shading, and individual
  5069. outlier points are plotted.
  5070. \end_layout
  5071. \end_inset
  5072. \end_layout
  5073. \end_inset
  5074. \end_layout
  5075. \begin_layout Standard
  5076. Figure
  5077. \begin_inset CommandInset ref
  5078. LatexCommand ref
  5079. reference "fig:ma-bx-rma-frma"
  5080. plural "false"
  5081. caps "false"
  5082. noprefix "false"
  5083. \end_inset
  5084. shows an MA plot of the RMA-normalized values against the fRMA-normalized
  5085. values for the same probe sets and arrays, corresponding to the first row
  5086. of Figure
  5087. \begin_inset CommandInset ref
  5088. LatexCommand ref
  5089. reference "fig:m-bx-violin"
  5090. plural "false"
  5091. caps "false"
  5092. noprefix "false"
  5093. \end_inset
  5094. .
  5095. This MA plot shows that not only is there a wide distribution of M-values,
  5096. but the trend of M-values is dependent on the average normalized intensity.
  5097. This is expected, since the overall trend represents the differences in
  5098. the quantile normalization step.
  5099. When running RMA, only the quantiles for these specific 20 arrays are used,
  5100. while for fRMA the quantile distribution is taking from all arrays used
  5101. in training.
  5102. Figure
  5103. \begin_inset CommandInset ref
  5104. LatexCommand ref
  5105. reference "fig:ma-bx-frma-frma"
  5106. plural "false"
  5107. caps "false"
  5108. noprefix "false"
  5109. \end_inset
  5110. shows a similar MA plot comparing 2 different fRMA normalizations, correspondin
  5111. g to the 6th row of Figure
  5112. \begin_inset CommandInset ref
  5113. LatexCommand ref
  5114. reference "fig:m-bx-violin"
  5115. plural "false"
  5116. caps "false"
  5117. noprefix "false"
  5118. \end_inset
  5119. .
  5120. The MA plot is very tightly centered around zero with no visible trend.
  5121. Figures
  5122. \begin_inset CommandInset ref
  5123. LatexCommand ref
  5124. reference "fig:m-pax-violin"
  5125. plural "false"
  5126. caps "false"
  5127. noprefix "false"
  5128. \end_inset
  5129. ,
  5130. \begin_inset CommandInset ref
  5131. LatexCommand ref
  5132. reference "fig:MA-PAX-rma-frma"
  5133. plural "false"
  5134. caps "false"
  5135. noprefix "false"
  5136. \end_inset
  5137. , and
  5138. \begin_inset CommandInset ref
  5139. LatexCommand ref
  5140. reference "fig:ma-bx-frma-frma"
  5141. plural "false"
  5142. caps "false"
  5143. noprefix "false"
  5144. \end_inset
  5145. show exactly the same information for the blood samples, once again comparing
  5146. the normalized expression values between normalizations for all probe sets
  5147. across 20 randomly selected test arrays.
  5148. Once again, there is a wider distribution of log ratios between RMA-normalized
  5149. values and fRMA-normalized, and a much tighter distribution when comparing
  5150. different fRMA normalizations to each other, indicating that the fRMA training
  5151. process is robust to random batch downsampling for the blood samples as
  5152. well.
  5153. \end_layout
  5154. \begin_layout Subsection
  5155. SVA, voom, and array weights improve model fit for methylation array data
  5156. \end_layout
  5157. \begin_layout Standard
  5158. \begin_inset ERT
  5159. status open
  5160. \begin_layout Plain Layout
  5161. \backslash
  5162. afterpage{
  5163. \end_layout
  5164. \begin_layout Plain Layout
  5165. \backslash
  5166. begin{landscape}
  5167. \end_layout
  5168. \end_inset
  5169. \end_layout
  5170. \begin_layout Standard
  5171. \begin_inset Float figure
  5172. wide false
  5173. sideways false
  5174. status open
  5175. \begin_layout Plain Layout
  5176. \begin_inset Flex TODO Note (inline)
  5177. status open
  5178. \begin_layout Plain Layout
  5179. Fix axis labels:
  5180. \begin_inset Quotes eld
  5181. \end_inset
  5182. log2 M-value
  5183. \begin_inset Quotes erd
  5184. \end_inset
  5185. is redundant because M-values are already log scale
  5186. \end_layout
  5187. \end_inset
  5188. \end_layout
  5189. \begin_layout Plain Layout
  5190. \begin_inset Float figure
  5191. wide false
  5192. sideways false
  5193. status collapsed
  5194. \begin_layout Plain Layout
  5195. \align center
  5196. \begin_inset Graphics
  5197. filename graphics/methylvoom/unadj.dupcor/meanvar-trends-PAGE1-CROP-RASTER.png
  5198. lyxscale 15
  5199. width 30col%
  5200. groupId voomaw-subfig
  5201. \end_inset
  5202. \end_layout
  5203. \begin_layout Plain Layout
  5204. \begin_inset Caption Standard
  5205. \begin_layout Plain Layout
  5206. \series bold
  5207. \begin_inset CommandInset label
  5208. LatexCommand label
  5209. name "fig:meanvar-basic"
  5210. \end_inset
  5211. Mean-variance trend for analysis A.
  5212. \end_layout
  5213. \end_inset
  5214. \end_layout
  5215. \end_inset
  5216. \begin_inset space \hfill{}
  5217. \end_inset
  5218. \begin_inset Float figure
  5219. wide false
  5220. sideways false
  5221. status collapsed
  5222. \begin_layout Plain Layout
  5223. \align center
  5224. \begin_inset Graphics
  5225. filename graphics/methylvoom/unadj.dupcor.sva.aw/meanvar-trends-PAGE1-CROP-RASTER.png
  5226. lyxscale 15
  5227. width 30col%
  5228. groupId voomaw-subfig
  5229. \end_inset
  5230. \end_layout
  5231. \begin_layout Plain Layout
  5232. \begin_inset Caption Standard
  5233. \begin_layout Plain Layout
  5234. \series bold
  5235. \begin_inset CommandInset label
  5236. LatexCommand label
  5237. name "fig:meanvar-sva-aw"
  5238. \end_inset
  5239. Mean-variance trend for analysis B.
  5240. \end_layout
  5241. \end_inset
  5242. \end_layout
  5243. \end_inset
  5244. \begin_inset space \hfill{}
  5245. \end_inset
  5246. \begin_inset Float figure
  5247. wide false
  5248. sideways false
  5249. status collapsed
  5250. \begin_layout Plain Layout
  5251. \align center
  5252. \begin_inset Graphics
  5253. filename graphics/methylvoom/unadj.dupcor.sva.voomaw/meanvar-trends-PAGE2-CROP-RASTER.png
  5254. lyxscale 15
  5255. width 30col%
  5256. groupId voomaw-subfig
  5257. \end_inset
  5258. \end_layout
  5259. \begin_layout Plain Layout
  5260. \begin_inset Caption Standard
  5261. \begin_layout Plain Layout
  5262. \series bold
  5263. \begin_inset CommandInset label
  5264. LatexCommand label
  5265. name "fig:meanvar-sva-voomaw"
  5266. \end_inset
  5267. Mean-variance trend after voom modeling in analysis C.
  5268. \end_layout
  5269. \end_inset
  5270. \end_layout
  5271. \end_inset
  5272. \end_layout
  5273. \begin_layout Plain Layout
  5274. \begin_inset Caption Standard
  5275. \begin_layout Plain Layout
  5276. \series bold
  5277. Mean-variance trend modeling in methylation array data.
  5278. \series default
  5279. The log2(standard deviation) for each probe is plotted against the probe's
  5280. average M-value across all samples as a black point, with some transparency
  5281. to make overplotting more visible, since there are about 450,000 points.
  5282. Density of points is also indicated by the dark blue contour lines.
  5283. The prior variance trend estimated by eBayes is shown in light blue, while
  5284. the lowess trend of the points is shown in red.
  5285. \end_layout
  5286. \end_inset
  5287. \end_layout
  5288. \end_inset
  5289. \end_layout
  5290. \begin_layout Standard
  5291. \begin_inset ERT
  5292. status open
  5293. \begin_layout Plain Layout
  5294. \backslash
  5295. end{landscape}
  5296. \end_layout
  5297. \begin_layout Plain Layout
  5298. }
  5299. \end_layout
  5300. \end_inset
  5301. \end_layout
  5302. \begin_layout Standard
  5303. Figure
  5304. \begin_inset CommandInset ref
  5305. LatexCommand ref
  5306. reference "fig:meanvar-basic"
  5307. plural "false"
  5308. caps "false"
  5309. noprefix "false"
  5310. \end_inset
  5311. shows the relationship between the mean M-value and the standard deviation
  5312. calculated for each probe in the methylation array data set.
  5313. A few features of the data are apparent.
  5314. First, the data are very strongly bimodal, with peaks in the density around
  5315. M-values of +4 and -4.
  5316. These modes correspond to methylation sites that are nearly 100% methylated
  5317. and nearly 100% unmethylated, respectively.
  5318. The strong bomodality indicates that a majority of probes interrogate sites
  5319. that fall into one of these two categories.
  5320. The points in between these modes represent sites that are either partially
  5321. methylated in many samples, or are fully methylated in some samples and
  5322. fully unmethylated in other samples, or some combination.
  5323. The next visible feature of the data is the W-shaped variance trend.
  5324. The upticks in the variance trend on either side are expected, based on
  5325. the sigmoid transformation exaggerating small differences at extreme M-values
  5326. (Figure
  5327. \begin_inset CommandInset ref
  5328. LatexCommand ref
  5329. reference "fig:Sigmoid-beta-m-mapping"
  5330. plural "false"
  5331. caps "false"
  5332. noprefix "false"
  5333. \end_inset
  5334. ).
  5335. However, the uptick in the center is interesting: it indicates that sites
  5336. that are not constitutitively methylated or unmethylated have a higher
  5337. variance.
  5338. This could be a genuine biological effect, or it could be spurious noise
  5339. that is only observable at sites with varying methylation.
  5340. \end_layout
  5341. \begin_layout Standard
  5342. In Figure
  5343. \begin_inset CommandInset ref
  5344. LatexCommand ref
  5345. reference "fig:meanvar-sva-aw"
  5346. plural "false"
  5347. caps "false"
  5348. noprefix "false"
  5349. \end_inset
  5350. , we see the mean-variance trend for the same methylation array data, this
  5351. time with surrogate variables and sample quality weights estimated from
  5352. the data and included in the model.
  5353. As expected, the overall average variance is smaller, since the surrogate
  5354. variables account for some of the variance.
  5355. In addition, the uptick in variance in the middle of the M-value range
  5356. has disappeared, turning the W shape into a wide U shape.
  5357. This indicates that the excess variance in the probes with intermediate
  5358. M-values was explained by systematic variations not correlated with known
  5359. covariates, and these variations were modeled by the surrogate variables.
  5360. The result is a nearly flat variance trend for the entire intermediate
  5361. M-value range from about -3 to +3.
  5362. In contrast, the excess variance at the extremes was not
  5363. \begin_inset Quotes eld
  5364. \end_inset
  5365. absorbed
  5366. \begin_inset Quotes erd
  5367. \end_inset
  5368. by the surrogate variables and remains in the plot, indicating that this
  5369. variation has no systematic component: probes with extreme M-values are
  5370. uniformly more variable across all samples, as expected.
  5371. \end_layout
  5372. \begin_layout Standard
  5373. Figure
  5374. \begin_inset CommandInset ref
  5375. LatexCommand ref
  5376. reference "fig:meanvar-sva-voomaw"
  5377. plural "false"
  5378. caps "false"
  5379. noprefix "false"
  5380. \end_inset
  5381. shows the mean-variance trend after fitting the model with the observation
  5382. weights assigned by voom based on the mean-variance trend shown in Figure
  5383. \begin_inset CommandInset ref
  5384. LatexCommand ref
  5385. reference "fig:meanvar-sva-aw"
  5386. plural "false"
  5387. caps "false"
  5388. noprefix "false"
  5389. \end_inset
  5390. .
  5391. As expected, the weights exactly counteract the trend in the data, resulting
  5392. in a nearly flat trend centered vertically at 1 (i.e.
  5393. 0 on the log scale).
  5394. This shows that the observations with extreme M-values have been appropriately
  5395. down-weighted to account for the fact that the noise in those observations
  5396. has been amplified by the non-linear M-value transformation.
  5397. In turn, this gives relatively more weight to observervations in the middle
  5398. region, which are more likely to correspond to probes measuring interesting
  5399. biology (not constitutively methylated or unmethylated).
  5400. \end_layout
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  5432. p-value
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  5441. Transplant Status
  5442. \end_layout
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  5448. F-test
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  5464. Diabetes Diagnosis
  5465. \end_layout
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  5471. t-test
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  5510. Age
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  5517. linear regression
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  5538. name "tab:weight-covariate-tests"
  5539. \end_inset
  5540. Association of sample weights with clinical covariates in methylation array
  5541. data.
  5542. \series default
  5543. Computed sample quality log weights were tested for significant association
  5544. with each of the variables in the model (1st column).
  5545. An appropriate test was selected for each variable (2nd column).
  5546. P-values for significant association are shown in the 3rd column.
  5547. \end_layout
  5548. \end_inset
  5549. \end_layout
  5550. \end_inset
  5551. \end_layout
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  5553. \begin_inset Flex TODO Note (inline)
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  5555. \begin_layout Plain Layout
  5556. Redo the sample weight boxplot with notches and without fill colors (and
  5557. update the legend)
  5558. \end_layout
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  5569. filename graphics/methylvoom/unadj.dupcor.sva.voomaw/sample-weights-PAGE3-CROP.pdf
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  5580. name "fig:diabetes-sample-weights"
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  5582. \series bold
  5583. Boxplot of sample quality weights grouped by diabetes diagnosis.
  5584. \series default
  5585. Sample were grouped based on diabetes diagnosis, and the distribution of
  5586. sample quality weights for each diagnosis was plotted.
  5587. \end_layout
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  5591. \end_layout
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  5595. To determine whether any of the known experimental factors had an impact
  5596. on data quality, the sample quality weights estimated from the data were
  5597. tested for association with each of the experimental factors (Table
  5598. \begin_inset CommandInset ref
  5599. LatexCommand ref
  5600. reference "tab:weight-covariate-tests"
  5601. plural "false"
  5602. caps "false"
  5603. noprefix "false"
  5604. \end_inset
  5605. ).
  5606. Diabetes diagnosis was found to have a potentially significant association
  5607. with the sample weights, with a t-test p-value of
  5608. \begin_inset Formula $1.06\times10^{-3}$
  5609. \end_inset
  5610. .
  5611. Figure
  5612. \begin_inset CommandInset ref
  5613. LatexCommand ref
  5614. reference "fig:diabetes-sample-weights"
  5615. plural "false"
  5616. caps "false"
  5617. noprefix "false"
  5618. \end_inset
  5619. shows the distribution of sample weights grouped by diabetes diagnosis.
  5620. The samples from patients with Type 2 diabetes were assigned significantly
  5621. lower weights than those from patients with Type 1 diabetes.
  5622. This indicates that the type 2 diabetes samples had an overall higher variance
  5623. on average across all probes.
  5624. \end_layout
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  5635. Consider transposing these tables
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  5810. Number of probes significant at 10% FDR.
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  5934. \begin_layout Plain Layout
  5935. 12,674
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  5942. 13,086
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  5949. \begin_inset Text
  5950. \begin_layout Plain Layout
  5951. TX vs CAN
  5952. \end_layout
  5953. \end_inset
  5954. </cell>
  5955. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
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  5958. 966
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  5965. 20,039
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  5970. \begin_inset Text
  5971. \begin_layout Plain Layout
  5972. 20,955
  5973. \end_layout
  5974. \end_inset
  5975. </cell>
  5976. </row>
  5977. </lyxtabular>
  5978. \end_inset
  5979. \end_layout
  5980. \begin_layout Plain Layout
  5981. \begin_inset Caption Standard
  5982. \begin_layout Plain Layout
  5983. \begin_inset CommandInset label
  5984. LatexCommand label
  5985. name "tab:methyl-est-nonnull"
  5986. \end_inset
  5987. Estimated number of non-null tests, using the method of
  5988. \begin_inset CommandInset citation
  5989. LatexCommand cite
  5990. key "Phipson2013"
  5991. literal "false"
  5992. \end_inset
  5993. .
  5994. \end_layout
  5995. \end_inset
  5996. \end_layout
  5997. \end_inset
  5998. \end_layout
  5999. \begin_layout Plain Layout
  6000. \begin_inset Caption Standard
  6001. \begin_layout Plain Layout
  6002. \series bold
  6003. Estimates of degree of differential methylation in for each contrast in
  6004. each analysis.
  6005. \series default
  6006. For each of the analyses in Table
  6007. \begin_inset CommandInset ref
  6008. LatexCommand ref
  6009. reference "tab:Summary-of-meth-analysis"
  6010. plural "false"
  6011. caps "false"
  6012. noprefix "false"
  6013. \end_inset
  6014. , these tables show the number of probes called significantly differentially
  6015. methylated at a threshold of 10% FDR for each comparison between TX and
  6016. the other 3 transplant statuses (
  6017. \begin_inset CommandInset ref
  6018. LatexCommand ref
  6019. reference "tab:methyl-num-signif"
  6020. plural "false"
  6021. caps "false"
  6022. noprefix "false"
  6023. \end_inset
  6024. ) and the estimated total number of probes that are differentially methylated
  6025. (
  6026. \begin_inset CommandInset ref
  6027. LatexCommand ref
  6028. reference "tab:methyl-est-nonnull"
  6029. plural "false"
  6030. caps "false"
  6031. noprefix "false"
  6032. \end_inset
  6033. ).
  6034. \end_layout
  6035. \end_inset
  6036. \end_layout
  6037. \end_inset
  6038. \end_layout
  6039. \begin_layout Standard
  6040. \begin_inset Float figure
  6041. wide false
  6042. sideways false
  6043. status collapsed
  6044. \begin_layout Plain Layout
  6045. \align center
  6046. \series bold
  6047. \begin_inset Float figure
  6048. wide false
  6049. sideways false
  6050. status collapsed
  6051. \begin_layout Plain Layout
  6052. \align center
  6053. \begin_inset Graphics
  6054. filename graphics/methylvoom/unadj.dupcor/pval-histograms-PAGE1.pdf
  6055. lyxscale 33
  6056. width 30col%
  6057. groupId meth-pval-hist
  6058. \end_inset
  6059. \end_layout
  6060. \begin_layout Plain Layout
  6061. \series bold
  6062. \begin_inset Caption Standard
  6063. \begin_layout Plain Layout
  6064. AR vs.
  6065. TX, Analysis A
  6066. \end_layout
  6067. \end_inset
  6068. \end_layout
  6069. \begin_layout Plain Layout
  6070. \end_layout
  6071. \end_inset
  6072. \begin_inset space \hfill{}
  6073. \end_inset
  6074. \begin_inset Float figure
  6075. wide false
  6076. sideways false
  6077. status collapsed
  6078. \begin_layout Plain Layout
  6079. \align center
  6080. \begin_inset Graphics
  6081. filename graphics/methylvoom/unadj.dupcor/pval-histograms-PAGE2.pdf
  6082. lyxscale 33
  6083. width 30col%
  6084. groupId meth-pval-hist
  6085. \end_inset
  6086. \end_layout
  6087. \begin_layout Plain Layout
  6088. \series bold
  6089. \begin_inset Caption Standard
  6090. \begin_layout Plain Layout
  6091. ADNR vs.
  6092. TX, Analysis A
  6093. \end_layout
  6094. \end_inset
  6095. \end_layout
  6096. \end_inset
  6097. \begin_inset space \hfill{}
  6098. \end_inset
  6099. \begin_inset Float figure
  6100. wide false
  6101. sideways false
  6102. status collapsed
  6103. \begin_layout Plain Layout
  6104. \align center
  6105. \begin_inset Graphics
  6106. filename graphics/methylvoom/unadj.dupcor/pval-histograms-PAGE3.pdf
  6107. lyxscale 33
  6108. width 30col%
  6109. groupId meth-pval-hist
  6110. \end_inset
  6111. \end_layout
  6112. \begin_layout Plain Layout
  6113. \series bold
  6114. \begin_inset Caption Standard
  6115. \begin_layout Plain Layout
  6116. CAN vs.
  6117. TX, Analysis A
  6118. \end_layout
  6119. \end_inset
  6120. \end_layout
  6121. \end_inset
  6122. \end_layout
  6123. \begin_layout Plain Layout
  6124. \align center
  6125. \series bold
  6126. \begin_inset Float figure
  6127. wide false
  6128. sideways false
  6129. status collapsed
  6130. \begin_layout Plain Layout
  6131. \align center
  6132. \begin_inset Graphics
  6133. filename graphics/methylvoom/unadj.dupcor.sva.aw/pval-histograms-PAGE1.pdf
  6134. lyxscale 33
  6135. width 30col%
  6136. groupId meth-pval-hist
  6137. \end_inset
  6138. \end_layout
  6139. \begin_layout Plain Layout
  6140. \series bold
  6141. \begin_inset Caption Standard
  6142. \begin_layout Plain Layout
  6143. AR vs.
  6144. TX, Analysis B
  6145. \end_layout
  6146. \end_inset
  6147. \end_layout
  6148. \end_inset
  6149. \begin_inset space \hfill{}
  6150. \end_inset
  6151. \begin_inset Float figure
  6152. wide false
  6153. sideways false
  6154. status collapsed
  6155. \begin_layout Plain Layout
  6156. \align center
  6157. \begin_inset Graphics
  6158. filename graphics/methylvoom/unadj.dupcor.sva.aw/pval-histograms-PAGE2.pdf
  6159. lyxscale 33
  6160. width 30col%
  6161. groupId meth-pval-hist
  6162. \end_inset
  6163. \end_layout
  6164. \begin_layout Plain Layout
  6165. \series bold
  6166. \begin_inset Caption Standard
  6167. \begin_layout Plain Layout
  6168. ADNR vs.
  6169. TX, Analysis B
  6170. \end_layout
  6171. \end_inset
  6172. \end_layout
  6173. \end_inset
  6174. \begin_inset space \hfill{}
  6175. \end_inset
  6176. \begin_inset Float figure
  6177. wide false
  6178. sideways false
  6179. status collapsed
  6180. \begin_layout Plain Layout
  6181. \align center
  6182. \begin_inset Graphics
  6183. filename graphics/methylvoom/unadj.dupcor.sva.aw/pval-histograms-PAGE3.pdf
  6184. lyxscale 33
  6185. width 30col%
  6186. groupId meth-pval-hist
  6187. \end_inset
  6188. \end_layout
  6189. \begin_layout Plain Layout
  6190. \series bold
  6191. \begin_inset Caption Standard
  6192. \begin_layout Plain Layout
  6193. CAN vs.
  6194. TX, Analysis B
  6195. \end_layout
  6196. \end_inset
  6197. \end_layout
  6198. \end_inset
  6199. \end_layout
  6200. \begin_layout Plain Layout
  6201. \align center
  6202. \series bold
  6203. \begin_inset Float figure
  6204. wide false
  6205. sideways false
  6206. status collapsed
  6207. \begin_layout Plain Layout
  6208. \align center
  6209. \begin_inset Graphics
  6210. filename graphics/methylvoom/unadj.dupcor.sva.voomaw/pval-histograms-PAGE1.pdf
  6211. lyxscale 33
  6212. width 30col%
  6213. groupId meth-pval-hist
  6214. \end_inset
  6215. \end_layout
  6216. \begin_layout Plain Layout
  6217. \series bold
  6218. \begin_inset Caption Standard
  6219. \begin_layout Plain Layout
  6220. AR vs.
  6221. TX, Analysis C
  6222. \end_layout
  6223. \end_inset
  6224. \end_layout
  6225. \end_inset
  6226. \begin_inset space \hfill{}
  6227. \end_inset
  6228. \begin_inset Float figure
  6229. wide false
  6230. sideways false
  6231. status collapsed
  6232. \begin_layout Plain Layout
  6233. \align center
  6234. \begin_inset Graphics
  6235. filename graphics/methylvoom/unadj.dupcor.sva.voomaw/pval-histograms-PAGE2.pdf
  6236. lyxscale 33
  6237. width 30col%
  6238. groupId meth-pval-hist
  6239. \end_inset
  6240. \end_layout
  6241. \begin_layout Plain Layout
  6242. \series bold
  6243. \begin_inset Caption Standard
  6244. \begin_layout Plain Layout
  6245. ADNR vs.
  6246. TX, Analysis C
  6247. \end_layout
  6248. \end_inset
  6249. \end_layout
  6250. \end_inset
  6251. \begin_inset space \hfill{}
  6252. \end_inset
  6253. \begin_inset Float figure
  6254. wide false
  6255. sideways false
  6256. status collapsed
  6257. \begin_layout Plain Layout
  6258. \align center
  6259. \begin_inset Graphics
  6260. filename graphics/methylvoom/unadj.dupcor.sva.voomaw/pval-histograms-PAGE3.pdf
  6261. lyxscale 33
  6262. width 30col%
  6263. groupId meth-pval-hist
  6264. \end_inset
  6265. \end_layout
  6266. \begin_layout Plain Layout
  6267. \series bold
  6268. \begin_inset Caption Standard
  6269. \begin_layout Plain Layout
  6270. CAN vs.
  6271. TX, Analysis C
  6272. \end_layout
  6273. \end_inset
  6274. \end_layout
  6275. \end_inset
  6276. \end_layout
  6277. \begin_layout Plain Layout
  6278. \begin_inset Caption Standard
  6279. \begin_layout Plain Layout
  6280. \series bold
  6281. \begin_inset CommandInset label
  6282. LatexCommand label
  6283. name "fig:meth-p-value-histograms"
  6284. \end_inset
  6285. Probe p-value histograms for each contrast in each analysis.
  6286. \end_layout
  6287. \end_inset
  6288. \end_layout
  6289. \end_inset
  6290. \end_layout
  6291. \begin_layout Standard
  6292. Table
  6293. \begin_inset CommandInset ref
  6294. LatexCommand ref
  6295. reference "tab:methyl-num-signif"
  6296. plural "false"
  6297. caps "false"
  6298. noprefix "false"
  6299. \end_inset
  6300. shows the number of significantly differentially methylated probes reported
  6301. by each analysis for each comparison of interest at an FDR of 10%.
  6302. As expected, the more elaborate analyses, B and C, report more significant
  6303. probes than the more basic analysis A, consistent with the conclusions
  6304. above that the data contain hidden systematic variations that must be modeled.
  6305. Table
  6306. \begin_inset CommandInset ref
  6307. LatexCommand ref
  6308. reference "tab:methyl-est-nonnull"
  6309. plural "false"
  6310. caps "false"
  6311. noprefix "false"
  6312. \end_inset
  6313. shows the estimated number differentially methylated probes for each test
  6314. from each analysis.
  6315. This was computed by estimating the proportion of null hypotheses that
  6316. were true using the method of
  6317. \begin_inset CommandInset citation
  6318. LatexCommand cite
  6319. key "Phipson2013"
  6320. literal "false"
  6321. \end_inset
  6322. and subtracting that fraction from the total number of probes, yielding
  6323. an estimate of the number of null hypotheses that are false based on the
  6324. distribution of p-values across the entire dataset.
  6325. Note that this does not identify which null hypotheses should be rejected
  6326. (i.e.
  6327. which probes are significant); it only estimates the true number of such
  6328. probes.
  6329. Once again, analyses B and C result it much larger estimates for the number
  6330. of differentially methylated probes.
  6331. In this case, analysis C, the only analysis that includes voom, estimates
  6332. the largest number of differentially methylated probes for all 3 contrasts.
  6333. If the assumptions of all the methods employed hold, then this represents
  6334. a gain in statistical power over the simpler analysis A.
  6335. Figure
  6336. \begin_inset CommandInset ref
  6337. LatexCommand ref
  6338. reference "fig:meth-p-value-histograms"
  6339. plural "false"
  6340. caps "false"
  6341. noprefix "false"
  6342. \end_inset
  6343. shows the p-value distributions for each test, from which the numbers in
  6344. Table
  6345. \begin_inset CommandInset ref
  6346. LatexCommand ref
  6347. reference "tab:methyl-est-nonnull"
  6348. plural "false"
  6349. caps "false"
  6350. noprefix "false"
  6351. \end_inset
  6352. were generated.
  6353. The distributions for analysis A all have a dip in density near zero, which
  6354. is a strong sign of a poor model fit.
  6355. The histograms for analyses B and C are more well-behaved, with a uniform
  6356. component stretching all the way from 0 to 1 representing the probes for
  6357. which the null hypotheses is true (no differential methylation), and a
  6358. zero-biased component representing the probes for which the null hypothesis
  6359. is false (differentially methylated).
  6360. These histograms do not indicate any major issues with the model fit.
  6361. \end_layout
  6362. \begin_layout Standard
  6363. \begin_inset Flex TODO Note (inline)
  6364. status open
  6365. \begin_layout Plain Layout
  6366. Maybe include the PCA plots before/after SVA effect subtraction?
  6367. \end_layout
  6368. \end_inset
  6369. \end_layout
  6370. \begin_layout Section
  6371. Discussion
  6372. \end_layout
  6373. \begin_layout Subsection
  6374. fRMA achieves clinically applicable normalization without sacrificing classifica
  6375. tion performance
  6376. \end_layout
  6377. \begin_layout Standard
  6378. As shown in Figure
  6379. \begin_inset CommandInset ref
  6380. LatexCommand ref
  6381. reference "fig:Classifier-probabilities-RMA"
  6382. plural "false"
  6383. caps "false"
  6384. noprefix "false"
  6385. \end_inset
  6386. , improper normalization, particularly separate normalization of training
  6387. and test samples, leads to unwanted biases in classification.
  6388. In a controlled experimental context, it is always possible to correct
  6389. this issue by normalizing all experimental samples together.
  6390. However, because it is not feasible to normalize all samples together in
  6391. a clinical context, a single-channel normalization is required is required.
  6392. \end_layout
  6393. \begin_layout Standard
  6394. The major concern in using a single-channel normalization is that non-single-cha
  6395. nnel methods can share information between arrays to improve the normalization,
  6396. and single-channel methods risk sacrificing the gains in normalization
  6397. accuracy that come from this information sharing.
  6398. In the case of RMA, this information sharing is accomplished through quantile
  6399. normalization and median polish steps.
  6400. The need for information sharing in quantile normalization can easily be
  6401. removed by learning a fixed set of quantiles from external data and normalizing
  6402. each array to these fixed quantiles, instead of the quantiles of the data
  6403. itself.
  6404. As long as the fixed quantiles are reasonable, the result will be similar
  6405. to standard RMA.
  6406. However, there is no analogous way to eliminate cross-array information
  6407. sharing in the median polish step, so fRMA replaces this with a weighted
  6408. average of probes on each array, with the weights learned from external
  6409. data.
  6410. This step of fRMA has the greatest potential to diverge from RMA un undesirable
  6411. ways.
  6412. \end_layout
  6413. \begin_layout Standard
  6414. However, when run on real data, fRMA performed at least as well as RMA in
  6415. both the internal validation and external validation tests.
  6416. This shows that fRMA can be used to normalize individual clinical samples
  6417. in a class prediction context without sacrificing the classifier performance
  6418. that would be obtained by using the more well-established RMA for normalization.
  6419. The other single-channel normalization method considered, SCAN, showed
  6420. some loss of AUC in the external validation test.
  6421. Based on these results, fRMA is the preferred normalization for clinical
  6422. samples in a class prediction context.
  6423. \end_layout
  6424. \begin_layout Subsection
  6425. Robust fRMA vectors can be generated for new array platforms
  6426. \end_layout
  6427. \begin_layout Standard
  6428. \begin_inset Flex TODO Note (inline)
  6429. status open
  6430. \begin_layout Plain Layout
  6431. Look up the exact numbers, do a find & replace for
  6432. \begin_inset Quotes eld
  6433. \end_inset
  6434. 850
  6435. \begin_inset Quotes erd
  6436. \end_inset
  6437. \end_layout
  6438. \end_inset
  6439. \end_layout
  6440. \begin_layout Standard
  6441. The published fRMA normalization vectors for the hgu133plus2 platform were
  6442. generated from a set of about 850 samples chosen from a wide range of tissues,
  6443. which the authors determined was sufficient to generate a robust set of
  6444. normalization vectors that could be applied across all tissues
  6445. \begin_inset CommandInset citation
  6446. LatexCommand cite
  6447. key "McCall2010"
  6448. literal "false"
  6449. \end_inset
  6450. .
  6451. Since we only had hthgu133pluspm for 2 tissues of interest, our needs were
  6452. more modest.
  6453. Even using only 130 samples in 26 batches of 5 samples each for kidney
  6454. biopsies, we were able to train a robust set of fRMA normalization vectors
  6455. that were not meaningfully affected by the random selection of 5 samples
  6456. from each batch.
  6457. As expected, the training process was just as robust for the blood samples
  6458. with 230 samples in 46 batches of 5 samples each.
  6459. Because these vectors were each generated using training samples from a
  6460. single tissue, they are not suitable for general use, unlike the vectors
  6461. provided with fRMA itself.
  6462. They are purpose-built for normalizing a specific type of sample on a specific
  6463. platform.
  6464. This is a mostly acceptable limitation in the context of developing a machine
  6465. learning classifier for diagnosing a disease based on samples of a specific
  6466. tissue.
  6467. \end_layout
  6468. \begin_layout Standard
  6469. \begin_inset Flex TODO Note (inline)
  6470. status open
  6471. \begin_layout Plain Layout
  6472. How to bring up that these custom vectors were used in another project by
  6473. someone else that was never published?
  6474. \end_layout
  6475. \end_inset
  6476. \end_layout
  6477. \begin_layout Subsection
  6478. Methylation array data can be successfully analyzed using existing techniques,
  6479. but machine learning poses additional challenges
  6480. \end_layout
  6481. \begin_layout Standard
  6482. Both analysis strategies B and C both yield a reasonable analysis, with
  6483. a mean-variance trend that matches the expected behavior for the non-linear
  6484. M-value transformation (Figure
  6485. \begin_inset CommandInset ref
  6486. LatexCommand ref
  6487. reference "fig:meanvar-sva-aw"
  6488. plural "false"
  6489. caps "false"
  6490. noprefix "false"
  6491. \end_inset
  6492. ) and well-behaved p-value distributions (Figure
  6493. \begin_inset CommandInset ref
  6494. LatexCommand ref
  6495. reference "fig:meth-p-value-histograms"
  6496. plural "false"
  6497. caps "false"
  6498. noprefix "false"
  6499. \end_inset
  6500. ).
  6501. These two analyses also yield similar numbers of significant probes (Table
  6502. \begin_inset CommandInset ref
  6503. LatexCommand ref
  6504. reference "tab:methyl-num-signif"
  6505. plural "false"
  6506. caps "false"
  6507. noprefix "false"
  6508. \end_inset
  6509. ) and similar estimates of the number of differentially methylated probes
  6510. (Table
  6511. \begin_inset CommandInset ref
  6512. LatexCommand ref
  6513. reference "tab:methyl-est-nonnull"
  6514. plural "false"
  6515. caps "false"
  6516. noprefix "false"
  6517. \end_inset
  6518. ).
  6519. The main difference between these two analyses is the method used to account
  6520. for the mean-variance trend.
  6521. In analysis B, the trend is estimated and applied at the probe level: each
  6522. probe's estimated variance is squeezed toward the trend using an empirical
  6523. Bayes procedure (Figure
  6524. \begin_inset CommandInset ref
  6525. LatexCommand ref
  6526. reference "fig:meanvar-sva-aw"
  6527. plural "false"
  6528. caps "false"
  6529. noprefix "false"
  6530. \end_inset
  6531. ).
  6532. In analysis C, the trend is still estimated at the probe level, but instead
  6533. of estimating a single variance value shared across all observations for
  6534. a given probe, the voom method computes an initial estiamte of the variance
  6535. for each observation individually based on where its model-fitted M-value
  6536. falls on the trend line and then assigns inverse-variance weights to model
  6537. the difference in variance between observations.
  6538. An overall variance is still estimated for each probe using the same empirical
  6539. Bayes method, but now the residual trend is flat (Figure
  6540. \begin_inset CommandInset ref
  6541. LatexCommand ref
  6542. reference "fig:meanvar-sva-voomaw"
  6543. plural "false"
  6544. caps "false"
  6545. noprefix "false"
  6546. \end_inset
  6547. ), indicating that the mean-variance trend is adequately modeled by scaling
  6548. the estimated variance for each observation using the weights computed
  6549. by voom.
  6550. \end_layout
  6551. \begin_layout Standard
  6552. The difference between the standard empirical Bayes trended variance modeling
  6553. (analysis B) and voom (analysis C) is analogous to the difference between
  6554. a t-test with equal variance and a t-test with unequal variance, except
  6555. that the unequal group variances used in the latter test are estimated
  6556. based on the mean-variance trend from all the probes rather than the data
  6557. for the specific probe being tested, thus stabilizing the group variance
  6558. estimates by sharing information between probes.
  6559. Allowing voom to model the variance using observation weights in this manner
  6560. allows the linear model fit to concentrate statistical power where it will
  6561. do the most good.
  6562. For example, if a particular probe's M-values are always at the extreme
  6563. of the M-value range (e.g.
  6564. less than -4) for ADNR samples, but the M-values for that probe in TX and
  6565. CAN samples are within the flat region of the mean-variance trend (between
  6566. -3 and +3), voom is able to down-weight the contribution of the high-variance
  6567. M-values from the ADNR samples in order to gain more statistical power
  6568. while testing for differential methylation between TX and CAN.
  6569. In contrast, modeling the mean-variance trend only at the probe level would
  6570. combine the high-variance ADNR samples and lower-variance samples from
  6571. other conditions and estimate an intermediate variance for this probe.
  6572. In practice, analysis B shows that this approach is adequate, but the voom
  6573. approach in analysis C is at least as good on all model fit criteria and
  6574. yields a larger estimate for the number of differentially methylated genes,
  6575. \emph on
  6576. and
  6577. \emph default
  6578. it matches up better with the theoretical
  6579. \end_layout
  6580. \begin_layout Standard
  6581. The significant association of diebetes diagnosis with sample quality is
  6582. interesting.
  6583. The samples with Type 2 diabetes tended to have more variation, averaged
  6584. across all probes, than those with Type 1 diabetes.
  6585. This is consistent with the consensus that type 2 disbetes and the associated
  6586. metabolic syndrome represent a broad dysregulation of the body's endocrine
  6587. signalling related to metabolism [citation needed].
  6588. This dysregulation could easily manifest as a greater degree of variation
  6589. in the DNA methylation patterns of affected tissues.
  6590. In contrast, Type 1 disbetes has a more specific cause and effect, so a
  6591. less variable methylation signature is expected.
  6592. \end_layout
  6593. \begin_layout Standard
  6594. This preliminary anlaysis suggests that some degree of differential methylation
  6595. exists between TX and each of the three types of transplant disfunction
  6596. studied.
  6597. Hence, it may be feasible to train a classifier to diagnose transplant
  6598. disfunction from DNA methylation array data.
  6599. However, the major importance of both SVA and sample quality weighting
  6600. for proper modeling of this data poses significant challenges for any attempt
  6601. at a machine learning on data of similar quality.
  6602. While these are easily used in a modeling context with full sample information,
  6603. neither of these methods is directly applicable in a machine learning context,
  6604. where the diagnosis is not known ahead of time.
  6605. If a machine learning approach for methylation-based diagnosis is to be
  6606. pursued, it will either require machine-learning-friendly methods to address
  6607. the same systematic trends in the data that SVA and sample quality weighting
  6608. address, or it will require higher quality data with substantially less
  6609. systematic perturbation of the data.
  6610. \end_layout
  6611. \begin_layout Chapter
  6612. Globin-blocking for more effective blood RNA-seq analysis in primate animal
  6613. model
  6614. \end_layout
  6615. \begin_layout Standard
  6616. \begin_inset Flex TODO Note (inline)
  6617. status open
  6618. \begin_layout Plain Layout
  6619. Choose between above and the paper title: Optimizing yield of deep RNA sequencin
  6620. g for gene expression profiling by globin reduction of peripheral blood
  6621. samples from cynomolgus monkeys (Macaca fascicularis).
  6622. \end_layout
  6623. \end_inset
  6624. \end_layout
  6625. \begin_layout Standard
  6626. \begin_inset Flex TODO Note (inline)
  6627. status open
  6628. \begin_layout Plain Layout
  6629. Chapter author list: https://tex.stackexchange.com/questions/156862/displaying-aut
  6630. hor-for-each-chapter-in-book Every chapter gets an author list, which may
  6631. or may not be part of a citation to a published/preprinted paper.
  6632. \end_layout
  6633. \end_inset
  6634. \end_layout
  6635. \begin_layout Standard
  6636. \begin_inset Flex TODO Note (inline)
  6637. status open
  6638. \begin_layout Plain Layout
  6639. Preprint then cite the paper
  6640. \end_layout
  6641. \end_inset
  6642. \end_layout
  6643. \begin_layout Section*
  6644. Abstract
  6645. \end_layout
  6646. \begin_layout Paragraph
  6647. Background
  6648. \end_layout
  6649. \begin_layout Standard
  6650. Primate blood contains high concentrations of globin messenger RNA.
  6651. Globin reduction is a standard technique used to improve the expression
  6652. results obtained by DNA microarrays on RNA from blood samples.
  6653. However, with whole transcriptome RNA-sequencing (RNA-seq) quickly replacing
  6654. microarrays for many applications, the impact of globin reduction for RNA-seq
  6655. has not been previously studied.
  6656. Moreover, no off-the-shelf kits are available for globin reduction in nonhuman
  6657. primates.
  6658. \end_layout
  6659. \begin_layout Paragraph
  6660. Results
  6661. \end_layout
  6662. \begin_layout Standard
  6663. Here we report a protocol for RNA-seq in primate blood samples that uses
  6664. complimentary oligonucleotides to block reverse transcription of the alpha
  6665. and beta globin genes.
  6666. In test samples from cynomolgus monkeys (Macaca fascicularis), this globin
  6667. blocking protocol approximately doubles the yield of informative (non-globin)
  6668. reads by greatly reducing the fraction of globin reads, while also improving
  6669. the consistency in sequencing depth between samples.
  6670. The increased yield enables detection of about 2000 more genes, significantly
  6671. increases the correlation in measured gene expression levels between samples,
  6672. and increases the sensitivity of differential gene expression tests.
  6673. \end_layout
  6674. \begin_layout Paragraph
  6675. Conclusions
  6676. \end_layout
  6677. \begin_layout Standard
  6678. These results show that globin blocking significantly improves the cost-effectiv
  6679. eness of mRNA sequencing in primate blood samples by doubling the yield
  6680. of useful reads, allowing detection of more genes, and improving the precision
  6681. of gene expression measurements.
  6682. Based on these results, a globin reducing or blocking protocol is recommended
  6683. for all RNA-seq studies of primate blood samples.
  6684. \end_layout
  6685. \begin_layout Section
  6686. Approach
  6687. \end_layout
  6688. \begin_layout Standard
  6689. \begin_inset Note Note
  6690. status open
  6691. \begin_layout Plain Layout
  6692. Consider putting some of this in the Intro chapter
  6693. \end_layout
  6694. \begin_layout Itemize
  6695. Cynomolgus monkeys as a model organism
  6696. \end_layout
  6697. \begin_deeper
  6698. \begin_layout Itemize
  6699. Highly related to humans
  6700. \end_layout
  6701. \begin_layout Itemize
  6702. Small size and short life cycle - good research animal
  6703. \end_layout
  6704. \begin_layout Itemize
  6705. Genomics resources still in development
  6706. \end_layout
  6707. \end_deeper
  6708. \begin_layout Itemize
  6709. Inadequacy of existing blood RNA-seq protocols
  6710. \end_layout
  6711. \begin_deeper
  6712. \begin_layout Itemize
  6713. Existing protocols use a separate globin pulldown step, slowing down processing
  6714. \end_layout
  6715. \end_deeper
  6716. \end_inset
  6717. \end_layout
  6718. \begin_layout Standard
  6719. Increasingly, researchers are turning to high-throughput mRNA sequencing
  6720. technologies (RNA-seq) in preference to expression microarrays for analysis
  6721. of gene expression
  6722. \begin_inset CommandInset citation
  6723. LatexCommand cite
  6724. key "Mutz2012"
  6725. literal "false"
  6726. \end_inset
  6727. .
  6728. The advantages are even greater for study of model organisms with no well-estab
  6729. lished array platforms available, such as the cynomolgus monkey (Macaca
  6730. fascicularis).
  6731. High fractions of globin mRNA are naturally present in mammalian peripheral
  6732. blood samples (up to 70% of total mRNA) and these are known to interfere
  6733. with the results of array-based expression profiling
  6734. \begin_inset CommandInset citation
  6735. LatexCommand cite
  6736. key "Winn2010"
  6737. literal "false"
  6738. \end_inset
  6739. .
  6740. The importance of globin reduction for RNA-seq of blood has only been evaluated
  6741. for a deepSAGE protocol on human samples
  6742. \begin_inset CommandInset citation
  6743. LatexCommand cite
  6744. key "Mastrokolias2012"
  6745. literal "false"
  6746. \end_inset
  6747. .
  6748. In the present report, we evaluated globin reduction using custom blocking
  6749. oligonucleotides for deep RNA-seq of peripheral blood samples from a nonhuman
  6750. primate, cynomolgus monkey, using the Illumina technology platform.
  6751. We demonstrate that globin reduction significantly improves the cost-effectiven
  6752. ess of RNA-seq in blood samples.
  6753. Thus, our protocol offers a significant advantage to any investigator planning
  6754. to use RNA-seq for gene expression profiling of nonhuman primate blood
  6755. samples.
  6756. Our method can be generally applied to any species by designing complementary
  6757. oligonucleotide blocking probes to the globin gene sequences of that species.
  6758. Indeed, any highly expressed but biologically uninformative transcripts
  6759. can also be blocked to further increase sequencing efficiency and value
  6760. \begin_inset CommandInset citation
  6761. LatexCommand cite
  6762. key "Arnaud2016"
  6763. literal "false"
  6764. \end_inset
  6765. .
  6766. \end_layout
  6767. \begin_layout Section
  6768. Methods
  6769. \end_layout
  6770. \begin_layout Subsection
  6771. Sample collection
  6772. \end_layout
  6773. \begin_layout Standard
  6774. All research reported here was done under IACUC-approved protocols at the
  6775. University of Miami and complied with all applicable federal and state
  6776. regulations and ethical principles for nonhuman primate research.
  6777. Blood draws occurred between 16 April 2012 and 18 June 2015.
  6778. The experimental system involved intrahepatic pancreatic islet transplantation
  6779. into Cynomolgus monkeys with induced diabetes mellitus with or without
  6780. concomitant infusion of mesenchymal stem cells.
  6781. Blood was collected at serial time points before and after transplantation
  6782. into PAXgene Blood RNA tubes (PreAnalytiX/Qiagen, Valencia, CA) at the
  6783. precise volume:volume ratio of 2.5 ml whole blood into 6.9 ml of PAX gene
  6784. additive.
  6785. \end_layout
  6786. \begin_layout Subsection
  6787. Globin Blocking
  6788. \end_layout
  6789. \begin_layout Standard
  6790. Four oligonucleotides were designed to hybridize to the 3’ end of the transcript
  6791. s for Cynomolgus HBA1, HBA2 and HBB, with two hybridization sites for HBB
  6792. and 2 sites for HBA (the chosen sites were identical in both HBA genes).
  6793. All oligos were purchased from Sigma and were entirely composed of 2’O-Me
  6794. bases with a C3 spacer positioned at the 3’ ends to prevent any polymerase
  6795. mediated primer extension.
  6796. \end_layout
  6797. \begin_layout Quote
  6798. HBA1/2 site 1: GCCCACUCAGACUUUAUUCAAAG-C3spacer
  6799. \end_layout
  6800. \begin_layout Quote
  6801. HBA1/2 site 2: GGUGCAAGGAGGGGAGGAG-C3spacer
  6802. \end_layout
  6803. \begin_layout Quote
  6804. HBB site 1: AAUGAAAAUAAAUGUUUUUUAUUAG-C3spacer
  6805. \end_layout
  6806. \begin_layout Quote
  6807. HBB site 2: CUCAAGGCCCUUCAUAAUAUCCC-C3spacer
  6808. \end_layout
  6809. \begin_layout Subsection
  6810. RNA-seq Library Preparation
  6811. \end_layout
  6812. \begin_layout Standard
  6813. Sequencing libraries were prepared with 200ng total RNA from each sample.
  6814. Polyadenylated mRNA was selected from 200 ng aliquots of cynomologus blood-deri
  6815. ved total RNA using Ambion Dynabeads Oligo(dT)25 beads (Invitrogen) following
  6816. manufacturer’s recommended protocol.
  6817. PolyA selected RNA was then combined with 8 pmol of HBA1/2 (site 1), 8
  6818. pmol of HBA1/2 (site 2), 12 pmol of HBB (site 1) and 12 pmol of HBB (site
  6819. 2) oligonucleotides.
  6820. In addition, 20 pmol of RT primer containing a portion of the Illumina
  6821. adapter sequence (B-oligo-dTV: GAGTTCCTTGGCACCCGAGAATTCCATTTTTTTTTTTTTTTTTTTV)
  6822. and 4 µL of 5X First Strand buffer (250 mM Tris-HCl pH 8.3, 375 mM KCl,
  6823. 15mM MgCl2) were added in a total volume of 15 µL.
  6824. The RNA was fragmented by heating this cocktail for 3 minutes at 95°C and
  6825. then placed on ice.
  6826. This was followed by the addition of 2 µL 0.1 M DTT, 1 µL RNaseOUT, 1 µL
  6827. 10mM dNTPs 10% biotin-16 aminoallyl-2’- dUTP and 10% biotin-16 aminoallyl-2’-
  6828. dCTP (TriLink Biotech, San Diego, CA), 1 µL Superscript II (200U/ µL, Thermo-Fi
  6829. sher).
  6830. A second “unblocked” library was prepared in the same way for each sample
  6831. but replacing the blocking oligos with an equivalent volume of water.
  6832. The reaction was carried out at 25°C for 15 minutes and 42°C for 40 minutes,
  6833. followed by incubation at 75°C for 10 minutes to inactivate the reverse
  6834. transcriptase.
  6835. \end_layout
  6836. \begin_layout Standard
  6837. The cDNA/RNA hybrid molecules were purified using 1.8X Ampure XP beads (Agencourt
  6838. ) following supplier’s recommended protocol.
  6839. The cDNA/RNA hybrid was eluted in 25 µL of 10 mM Tris-HCl pH 8.0, and then
  6840. bound to 25 µL of M280 Magnetic Streptavidin beads washed per recommended
  6841. protocol (Thermo-Fisher).
  6842. After 30 minutes of binding, beads were washed one time in 100 µL 0.1N NaOH
  6843. to denature and remove the bound RNA, followed by two 100 µL washes with
  6844. 1X TE buffer.
  6845. \end_layout
  6846. \begin_layout Standard
  6847. Subsequent attachment of the 5-prime Illumina A adapter was performed by
  6848. on-bead random primer extension of the following sequence (A-N8 primer:
  6849. TTCAGAGTTCTACAGTCCGACGATCNNNNNNNN).
  6850. Briefly, beads were resuspended in a 20 µL reaction containing 5 µM A-N8
  6851. primer, 40mM Tris-HCl pH 7.5, 20mM MgCl2, 50mM NaCl, 0.325U/µL Sequenase
  6852. 2.0 (Affymetrix, Santa Clara, CA), 0.0025U/µL inorganic pyrophosphatase (Affymetr
  6853. ix) and 300 µM each dNTP.
  6854. Reaction was incubated at 22°C for 30 minutes, then beads were washed 2
  6855. times with 1X TE buffer (200µL).
  6856. \end_layout
  6857. \begin_layout Standard
  6858. The magnetic streptavidin beads were resuspended in 34 µL nuclease-free
  6859. water and added directly to a PCR tube.
  6860. The two Illumina protocol-specified PCR primers were added at 0.53 µM (Illumina
  6861. TruSeq Universal Primer 1 and Illumina TruSeq barcoded PCR primer 2), along
  6862. with 40 µL 2X KAPA HiFi Hotstart ReadyMix (KAPA, Willmington MA) and thermocycl
  6863. ed as follows: starting with 98°C (2 min-hold); 15 cycles of 98°C, 20sec;
  6864. 60°C, 30sec; 72°C, 30sec; and finished with a 72°C (2 min-hold).
  6865. \end_layout
  6866. \begin_layout Standard
  6867. PCR products were purified with 1X Ampure Beads following manufacturer’s
  6868. recommended protocol.
  6869. Libraries were then analyzed using the Agilent TapeStation and quantitation
  6870. of desired size range was performed by “smear analysis”.
  6871. Samples were pooled in equimolar batches of 16 samples.
  6872. Pooled libraries were size selected on 2% agarose gels (E-Gel EX Agarose
  6873. Gels; Thermo-Fisher).
  6874. Products were cut between 250 and 350 bp (corresponding to insert sizes
  6875. of 130 to 230 bps).
  6876. Finished library pools were then sequenced on the Illumina NextSeq500 instrumen
  6877. t with 75 base read lengths.
  6878. \end_layout
  6879. \begin_layout Subsection
  6880. Read alignment and counting
  6881. \end_layout
  6882. \begin_layout Standard
  6883. Reads were aligned to the cynomolgus genome using STAR
  6884. \begin_inset CommandInset citation
  6885. LatexCommand cite
  6886. key "Dobin2013,Wilson2013"
  6887. literal "false"
  6888. \end_inset
  6889. .
  6890. Counts of uniquely mapped reads were obtained for every gene in each sample
  6891. with the “featureCounts” function from the Rsubread package, using each
  6892. of the three possibilities for the “strandSpecific” option: sense, antisense,
  6893. and unstranded
  6894. \begin_inset CommandInset citation
  6895. LatexCommand cite
  6896. key "Liao2014"
  6897. literal "false"
  6898. \end_inset
  6899. .
  6900. A few artifacts in the cynomolgus genome annotation complicated read counting.
  6901. First, no ortholog is annotated for alpha globin in the cynomolgus genome,
  6902. presumably because the human genome has two alpha globin genes with nearly
  6903. identical sequences, making the orthology relationship ambiguous.
  6904. However, two loci in the cynomolgus genome are as “hemoglobin subunit alpha-lik
  6905. e” (LOC102136192 and LOC102136846).
  6906. LOC102136192 is annotated as a pseudogene while LOC102136846 is annotated
  6907. as protein-coding.
  6908. Our globin reduction protocol was designed to include blocking of these
  6909. two genes.
  6910. Indeed, these two genes have almost the same read counts in each library
  6911. as the properly-annotated HBB gene and much larger counts than any other
  6912. gene in the unblocked libraries, giving confidence that reads derived from
  6913. the real alpha globin are mapping to both genes.
  6914. Thus, reads from both of these loci were counted as alpha globin reads
  6915. in all further analyses.
  6916. The second artifact is a small, uncharacterized non-coding RNA gene (LOC1021365
  6917. 91), which overlaps the HBA-like gene (LOC102136192) on the opposite strand.
  6918. If counting is not performed in stranded mode (or if a non-strand-specific
  6919. sequencing protocol is used), many reads mapping to the globin gene will
  6920. be discarded as ambiguous due to their overlap with this ncRNA gene, resulting
  6921. in significant undercounting of globin reads.
  6922. Therefore, stranded sense counts were used for all further analysis in
  6923. the present study to insure that we accurately accounted for globin transcript
  6924. reduction.
  6925. However, we note that stranded reads are not necessary for RNA-seq using
  6926. our protocol in standard practice.
  6927. \end_layout
  6928. \begin_layout Subsection
  6929. Normalization and Exploratory Data Analysis
  6930. \end_layout
  6931. \begin_layout Standard
  6932. Libraries were normalized by computing scaling factors using the edgeR package’s
  6933. Trimmed Mean of M-values method
  6934. \begin_inset CommandInset citation
  6935. LatexCommand cite
  6936. key "Robinson2010"
  6937. literal "false"
  6938. \end_inset
  6939. .
  6940. Log2 counts per million values (logCPM) were calculated using the cpm function
  6941. in edgeR for individual samples and aveLogCPM function for averages across
  6942. groups of samples, using those functions’ default prior count values to
  6943. avoid taking the logarithm of 0.
  6944. Genes were considered “present” if their average normalized logCPM values
  6945. across all libraries were at least -1.
  6946. Normalizing for gene length was unnecessary because the sequencing protocol
  6947. is 3’-biased and hence the expected read count for each gene is related
  6948. to the transcript’s copy number but not its length.
  6949. \end_layout
  6950. \begin_layout Standard
  6951. In order to assess the effect of blocking on reproducibility, Pearson and
  6952. Spearman correlation coefficients were computed between the logCPM values
  6953. for every pair of libraries within the globin-blocked (GB) and unblocked
  6954. (non-GB) groups, and edgeR's “estimateDisp” function was used to compute
  6955. negative binomial dispersions separately for the two groups
  6956. \begin_inset CommandInset citation
  6957. LatexCommand cite
  6958. key "Chen2014"
  6959. literal "false"
  6960. \end_inset
  6961. .
  6962. \end_layout
  6963. \begin_layout Subsection
  6964. Differential Expression Analysis
  6965. \end_layout
  6966. \begin_layout Standard
  6967. All tests for differential gene expression were performed using edgeR, by
  6968. first fitting a negative binomial generalized linear model to the counts
  6969. and normalization factors and then performing a quasi-likelihood F-test
  6970. with robust estimation of outlier gene dispersions
  6971. \begin_inset CommandInset citation
  6972. LatexCommand cite
  6973. key "Lund2012,Phipson2016"
  6974. literal "false"
  6975. \end_inset
  6976. .
  6977. To investigate the effects of globin blocking on each gene, an additive
  6978. model was fit to the full data with coefficients for globin blocking and
  6979. SampleID.
  6980. To test the effect of globin blocking on detection of differentially expressed
  6981. genes, the GB samples and non-GB samples were each analyzed independently
  6982. as follows: for each animal with both a pre-transplant and a post-transplant
  6983. time point in the data set, the pre-transplant sample and the earliest
  6984. post-transplant sample were selected, and all others were excluded, yielding
  6985. a pre-/post-transplant pair of samples for each animal (N=7 animals with
  6986. paired samples).
  6987. These samples were analyzed for pre-transplant vs.
  6988. post-transplant differential gene expression while controlling for inter-animal
  6989. variation using an additive model with coefficients for transplant and
  6990. animal ID.
  6991. In all analyses, p-values were adjusted using the Benjamini-Hochberg procedure
  6992. for FDR control
  6993. \begin_inset CommandInset citation
  6994. LatexCommand cite
  6995. key "Benjamini1995"
  6996. literal "false"
  6997. \end_inset
  6998. .
  6999. \end_layout
  7000. \begin_layout Standard
  7001. \begin_inset Note Note
  7002. status open
  7003. \begin_layout Itemize
  7004. New blood RNA-seq protocol to block reverse transcription of globin genes
  7005. \end_layout
  7006. \begin_layout Itemize
  7007. Blood RNA-seq time course after transplants with/without MSC infusion
  7008. \end_layout
  7009. \end_inset
  7010. \end_layout
  7011. \begin_layout Section
  7012. Results
  7013. \end_layout
  7014. \begin_layout Subsection
  7015. Globin blocking yields a larger and more consistent fraction of useful reads
  7016. \end_layout
  7017. \begin_layout Standard
  7018. \begin_inset ERT
  7019. status open
  7020. \begin_layout Plain Layout
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  7025. \backslash
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  7027. \end_layout
  7028. \end_inset
  7029. \end_layout
  7030. \begin_layout Standard
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  7032. placement p
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  7034. sideways false
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  7070. Percent of Total Reads
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  7107. Percent of Genic Reads
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  7120. \begin_inset Text
  7121. \begin_layout Plain Layout
  7122. GB
  7123. \end_layout
  7124. \end_inset
  7125. </cell>
  7126. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
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  7138. \uwave off
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  7140. \color none
  7141. Non-globin Reads
  7142. \end_layout
  7143. \end_inset
  7144. </cell>
  7145. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7146. \begin_inset Text
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  7155. \xout off
  7156. \uuline off
  7157. \uwave off
  7158. \noun off
  7159. \color none
  7160. Globin Reads
  7161. \end_layout
  7162. \end_inset
  7163. </cell>
  7164. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7165. \begin_inset Text
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  7174. \xout off
  7175. \uuline off
  7176. \uwave off
  7177. \noun off
  7178. \color none
  7179. All Genic Reads
  7180. \end_layout
  7181. \end_inset
  7182. </cell>
  7183. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7184. \begin_inset Text
  7185. \begin_layout Plain Layout
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  7188. \shape up
  7189. \size normal
  7190. \emph off
  7191. \bar no
  7192. \strikeout off
  7193. \xout off
  7194. \uuline off
  7195. \uwave off
  7196. \noun off
  7197. \color none
  7198. All Aligned Reads
  7199. \end_layout
  7200. \end_inset
  7201. </cell>
  7202. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7203. \begin_inset Text
  7204. \begin_layout Plain Layout
  7205. \family roman
  7206. \series medium
  7207. \shape up
  7208. \size normal
  7209. \emph off
  7210. \bar no
  7211. \strikeout off
  7212. \xout off
  7213. \uuline off
  7214. \uwave off
  7215. \noun off
  7216. \color none
  7217. Non-globin Reads
  7218. \end_layout
  7219. \end_inset
  7220. </cell>
  7221. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  7222. \begin_inset Text
  7223. \begin_layout Plain Layout
  7224. \family roman
  7225. \series medium
  7226. \shape up
  7227. \size normal
  7228. \emph off
  7229. \bar no
  7230. \strikeout off
  7231. \xout off
  7232. \uuline off
  7233. \uwave off
  7234. \noun off
  7235. \color none
  7236. Globin Reads
  7237. \end_layout
  7238. \end_inset
  7239. </cell>
  7240. </row>
  7241. <row>
  7242. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  7243. \begin_inset Text
  7244. \begin_layout Plain Layout
  7245. \family roman
  7246. \series medium
  7247. \shape up
  7248. \size normal
  7249. \emph off
  7250. \bar no
  7251. \strikeout off
  7252. \xout off
  7253. \uuline off
  7254. \uwave off
  7255. \noun off
  7256. \color none
  7257. Yes
  7258. \end_layout
  7259. \end_inset
  7260. </cell>
  7261. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  7262. \begin_inset Text
  7263. \begin_layout Plain Layout
  7264. \family roman
  7265. \series medium
  7266. \shape up
  7267. \size normal
  7268. \emph off
  7269. \bar no
  7270. \strikeout off
  7271. \xout off
  7272. \uuline off
  7273. \uwave off
  7274. \noun off
  7275. \color none
  7276. 50.4% ± 6.82
  7277. \end_layout
  7278. \end_inset
  7279. </cell>
  7280. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  7281. \begin_inset Text
  7282. \begin_layout Plain Layout
  7283. \family roman
  7284. \series medium
  7285. \shape up
  7286. \size normal
  7287. \emph off
  7288. \bar no
  7289. \strikeout off
  7290. \xout off
  7291. \uuline off
  7292. \uwave off
  7293. \noun off
  7294. \color none
  7295. 3.48% ± 2.94
  7296. \end_layout
  7297. \end_inset
  7298. </cell>
  7299. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  7300. \begin_inset Text
  7301. \begin_layout Plain Layout
  7302. \family roman
  7303. \series medium
  7304. \shape up
  7305. \size normal
  7306. \emph off
  7307. \bar no
  7308. \strikeout off
  7309. \xout off
  7310. \uuline off
  7311. \uwave off
  7312. \noun off
  7313. \color none
  7314. 53.9% ± 6.81
  7315. \end_layout
  7316. \end_inset
  7317. </cell>
  7318. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  7319. \begin_inset Text
  7320. \begin_layout Plain Layout
  7321. \family roman
  7322. \series medium
  7323. \shape up
  7324. \size normal
  7325. \emph off
  7326. \bar no
  7327. \strikeout off
  7328. \xout off
  7329. \uuline off
  7330. \uwave off
  7331. \noun off
  7332. \color none
  7333. 89.7% ± 2.40
  7334. \end_layout
  7335. \end_inset
  7336. </cell>
  7337. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  7338. \begin_inset Text
  7339. \begin_layout Plain Layout
  7340. \family roman
  7341. \series medium
  7342. \shape up
  7343. \size normal
  7344. \emph off
  7345. \bar no
  7346. \strikeout off
  7347. \xout off
  7348. \uuline off
  7349. \uwave off
  7350. \noun off
  7351. \color none
  7352. 93.5% ± 5.25
  7353. \end_layout
  7354. \end_inset
  7355. </cell>
  7356. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  7357. \begin_inset Text
  7358. \begin_layout Plain Layout
  7359. \family roman
  7360. \series medium
  7361. \shape up
  7362. \size normal
  7363. \emph off
  7364. \bar no
  7365. \strikeout off
  7366. \xout off
  7367. \uuline off
  7368. \uwave off
  7369. \noun off
  7370. \color none
  7371. 6.49% ± 5.25
  7372. \end_layout
  7373. \end_inset
  7374. </cell>
  7375. </row>
  7376. <row>
  7377. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7378. \begin_inset Text
  7379. \begin_layout Plain Layout
  7380. \family roman
  7381. \series medium
  7382. \shape up
  7383. \size normal
  7384. \emph off
  7385. \bar no
  7386. \strikeout off
  7387. \xout off
  7388. \uuline off
  7389. \uwave off
  7390. \noun off
  7391. \color none
  7392. No
  7393. \end_layout
  7394. \end_inset
  7395. </cell>
  7396. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7397. \begin_inset Text
  7398. \begin_layout Plain Layout
  7399. \family roman
  7400. \series medium
  7401. \shape up
  7402. \size normal
  7403. \emph off
  7404. \bar no
  7405. \strikeout off
  7406. \xout off
  7407. \uuline off
  7408. \uwave off
  7409. \noun off
  7410. \color none
  7411. 26.3% ± 8.95
  7412. \end_layout
  7413. \end_inset
  7414. </cell>
  7415. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7416. \begin_inset Text
  7417. \begin_layout Plain Layout
  7418. \family roman
  7419. \series medium
  7420. \shape up
  7421. \size normal
  7422. \emph off
  7423. \bar no
  7424. \strikeout off
  7425. \xout off
  7426. \uuline off
  7427. \uwave off
  7428. \noun off
  7429. \color none
  7430. 44.6% ± 16.6
  7431. \end_layout
  7432. \end_inset
  7433. </cell>
  7434. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7435. \begin_inset Text
  7436. \begin_layout Plain Layout
  7437. \family roman
  7438. \series medium
  7439. \shape up
  7440. \size normal
  7441. \emph off
  7442. \bar no
  7443. \strikeout off
  7444. \xout off
  7445. \uuline off
  7446. \uwave off
  7447. \noun off
  7448. \color none
  7449. 70.1% ± 9.38
  7450. \end_layout
  7451. \end_inset
  7452. </cell>
  7453. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7454. \begin_inset Text
  7455. \begin_layout Plain Layout
  7456. \family roman
  7457. \series medium
  7458. \shape up
  7459. \size normal
  7460. \emph off
  7461. \bar no
  7462. \strikeout off
  7463. \xout off
  7464. \uuline off
  7465. \uwave off
  7466. \noun off
  7467. \color none
  7468. 90.7% ± 5.16
  7469. \end_layout
  7470. \end_inset
  7471. </cell>
  7472. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  7473. \begin_inset Text
  7474. \begin_layout Plain Layout
  7475. \family roman
  7476. \series medium
  7477. \shape up
  7478. \size normal
  7479. \emph off
  7480. \bar no
  7481. \strikeout off
  7482. \xout off
  7483. \uuline off
  7484. \uwave off
  7485. \noun off
  7486. \color none
  7487. 38.8% ± 17.1
  7488. \end_layout
  7489. \end_inset
  7490. </cell>
  7491. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  7492. \begin_inset Text
  7493. \begin_layout Plain Layout
  7494. \family roman
  7495. \series medium
  7496. \shape up
  7497. \size normal
  7498. \emph off
  7499. \bar no
  7500. \strikeout off
  7501. \xout off
  7502. \uuline off
  7503. \uwave off
  7504. \noun off
  7505. \color none
  7506. 61.2% ± 17.1
  7507. \end_layout
  7508. \end_inset
  7509. </cell>
  7510. </row>
  7511. </lyxtabular>
  7512. \end_inset
  7513. \end_layout
  7514. \begin_layout Plain Layout
  7515. \begin_inset Caption Standard
  7516. \begin_layout Plain Layout
  7517. \series bold
  7518. \begin_inset Argument 1
  7519. status collapsed
  7520. \begin_layout Plain Layout
  7521. Fractions of reads mapping to genomic features in GB and non-GB samples.
  7522. \end_layout
  7523. \end_inset
  7524. \begin_inset CommandInset label
  7525. LatexCommand label
  7526. name "tab:Fractions-of-reads"
  7527. \end_inset
  7528. Fractions of reads mapping to genomic features in GB and non-GB samples.
  7529. \series default
  7530. All values are given as mean ± standard deviation.
  7531. \end_layout
  7532. \end_inset
  7533. \end_layout
  7534. \end_inset
  7535. \end_layout
  7536. \begin_layout Standard
  7537. \begin_inset ERT
  7538. status open
  7539. \begin_layout Plain Layout
  7540. \backslash
  7541. end{landscape}
  7542. \end_layout
  7543. \begin_layout Plain Layout
  7544. }
  7545. \end_layout
  7546. \end_inset
  7547. \end_layout
  7548. \begin_layout Standard
  7549. The objective of the present study was to validate a new protocol for deep
  7550. RNA-seq of whole blood drawn into PaxGene tubes from cynomolgus monkeys
  7551. undergoing islet transplantation, with particular focus on minimizing the
  7552. loss of useful sequencing space to uninformative globin reads.
  7553. The details of the analysis with respect to transplant outcomes and the
  7554. impact of mesenchymal stem cell treatment will be reported in a separate
  7555. manuscript (in preparation).
  7556. To focus on the efficacy of our globin blocking protocol, 37 blood samples,
  7557. 16 from pre-transplant and 21 from post-transplant time points, were each
  7558. prepped once with and once without globin blocking oligos, and were then
  7559. sequenced on an Illumina NextSeq500 instrument.
  7560. The number of reads aligning to each gene in the cynomolgus genome was
  7561. counted.
  7562. Table 1 summarizes the distribution of read fractions among the GB and
  7563. non-GB libraries.
  7564. In the libraries with no globin blocking, globin reads made up an average
  7565. of 44.6% of total input reads, while reads assigned to all other genes made
  7566. up an average of 26.3%.
  7567. The remaining reads either aligned to intergenic regions (that include
  7568. long non-coding RNAs) or did not align with any annotated transcripts in
  7569. the current build of the cynomolgus genome.
  7570. In the GB libraries, globin reads made up only 3.48% and reads assigned
  7571. to all other genes increased to 50.4%.
  7572. Thus, globin blocking resulted in a 92.2% reduction in globin reads and
  7573. a 91.6% increase in yield of useful non-globin reads.
  7574. \end_layout
  7575. \begin_layout Standard
  7576. This reduction is not quite as efficient as the previous analysis showed
  7577. for human samples by DeepSAGE (<0.4% globin reads after globin reduction)
  7578. \begin_inset CommandInset citation
  7579. LatexCommand cite
  7580. key "Mastrokolias2012"
  7581. literal "false"
  7582. \end_inset
  7583. .
  7584. Nonetheless, this degree of globin reduction is sufficient to nearly double
  7585. the yield of useful reads.
  7586. Thus, globin blocking cuts the required sequencing effort (and costs) to
  7587. achieve a target coverage depth by almost 50%.
  7588. Consistent with this near doubling of yield, the average difference in
  7589. un-normalized logCPM across all genes between the GB libraries and non-GB
  7590. libraries is approximately 1 (mean = 1.01, median = 1.08), an overall 2-fold
  7591. increase.
  7592. Un-normalized values are used here because the TMM normalization correctly
  7593. identifies this 2-fold difference as biologically irrelevant and removes
  7594. it.
  7595. \end_layout
  7596. \begin_layout Standard
  7597. \begin_inset Float figure
  7598. wide false
  7599. sideways false
  7600. status collapsed
  7601. \begin_layout Plain Layout
  7602. \align center
  7603. \begin_inset Graphics
  7604. filename graphics/Globin Paper/figure1 - globin-fractions.pdf
  7605. lyxscale 50
  7606. width 75col%
  7607. \end_inset
  7608. \end_layout
  7609. \begin_layout Plain Layout
  7610. \begin_inset Caption Standard
  7611. \begin_layout Plain Layout
  7612. \series bold
  7613. \begin_inset Argument 1
  7614. status collapsed
  7615. \begin_layout Plain Layout
  7616. Fraction of genic reads in each sample aligned to non-globin genes, with
  7617. and without globin blocking (GB).
  7618. \end_layout
  7619. \end_inset
  7620. \begin_inset CommandInset label
  7621. LatexCommand label
  7622. name "fig:Fraction-of-genic-reads"
  7623. \end_inset
  7624. Fraction of genic reads in each sample aligned to non-globin genes, with
  7625. and without globin blocking (GB).
  7626. \series default
  7627. All reads in each sequencing library were aligned to the cyno genome, and
  7628. the number of reads uniquely aligning to each gene was counted.
  7629. For each sample, counts were summed separately for all globin genes and
  7630. for the remainder of the genes (non-globin genes), and the fraction of
  7631. genic reads aligned to non-globin genes was computed.
  7632. Each point represents an individual sample.
  7633. Gray + signs indicate the means for globin-blocked libraries and unblocked
  7634. libraries.
  7635. The overall distribution for each group is represented as a notched box
  7636. plots.
  7637. Points are randomly spread vertically to avoid excessive overlapping.
  7638. \end_layout
  7639. \end_inset
  7640. \end_layout
  7641. \end_inset
  7642. \end_layout
  7643. \begin_layout Standard
  7644. Another important aspect is that the standard deviations in Table
  7645. \begin_inset CommandInset ref
  7646. LatexCommand ref
  7647. reference "tab:Fractions-of-reads"
  7648. plural "false"
  7649. caps "false"
  7650. noprefix "false"
  7651. \end_inset
  7652. are uniformly smaller in the GB samples than the non-GB ones, indicating
  7653. much greater consistency of yield.
  7654. This is best seen in the percentage of non-globin reads as a fraction of
  7655. total reads aligned to annotated genes (genic reads).
  7656. For the non-GB samples, this measure ranges from 10.9% to 80.9%, while for
  7657. the GB samples it ranges from 81.9% to 99.9% (Figure
  7658. \begin_inset CommandInset ref
  7659. LatexCommand ref
  7660. reference "fig:Fraction-of-genic-reads"
  7661. plural "false"
  7662. caps "false"
  7663. noprefix "false"
  7664. \end_inset
  7665. ).
  7666. This means that for applications where it is critical that each sample
  7667. achieve a specified minimum coverage in order to provide useful information,
  7668. it would be necessary to budget up to 10 times the sequencing depth per
  7669. sample without globin blocking, even though the average yield improvement
  7670. for globin blocking is only 2-fold, because every sample has a chance of
  7671. being 90% globin and 10% useful reads.
  7672. Hence, the more consistent behavior of GB samples makes planning an experiment
  7673. easier and more efficient because it eliminates the need to over-sequence
  7674. every sample in order to guard against the worst case of a high-globin
  7675. fraction.
  7676. \end_layout
  7677. \begin_layout Subsection
  7678. Globin blocking lowers the noise floor and allows detection of about 2000
  7679. more genes
  7680. \end_layout
  7681. \begin_layout Standard
  7682. \begin_inset Flex TODO Note (inline)
  7683. status open
  7684. \begin_layout Plain Layout
  7685. Remove redundant titles from figures
  7686. \end_layout
  7687. \end_inset
  7688. \end_layout
  7689. \begin_layout Standard
  7690. \begin_inset Float figure
  7691. wide false
  7692. sideways false
  7693. status collapsed
  7694. \begin_layout Plain Layout
  7695. \align center
  7696. \begin_inset Graphics
  7697. filename graphics/Globin Paper/figure2 - aveLogCPM-colored.pdf
  7698. lyxscale 50
  7699. height 60theight%
  7700. \end_inset
  7701. \end_layout
  7702. \begin_layout Plain Layout
  7703. \begin_inset Caption Standard
  7704. \begin_layout Plain Layout
  7705. \series bold
  7706. \begin_inset Argument 1
  7707. status collapsed
  7708. \begin_layout Plain Layout
  7709. Distributions of average group gene abundances when normalized separately
  7710. or together.
  7711. \end_layout
  7712. \end_inset
  7713. \begin_inset CommandInset label
  7714. LatexCommand label
  7715. name "fig:logcpm-dists"
  7716. \end_inset
  7717. Distributions of average group gene abundances when normalized separately
  7718. or together.
  7719. \series default
  7720. All reads in each sequencing library were aligned to the cyno genome, and
  7721. the number of reads uniquely aligning to each gene was counted.
  7722. Genes with zero counts in all libraries were discarded.
  7723. Libraries were normalized using the TMM method.
  7724. Libraries were split into globin-blocked (GB) and non-GB groups and the
  7725. average abundance for each gene in both groups, measured in log2 counts
  7726. per million reads counted, was computed using the aveLogCPM function.
  7727. The distribution of average gene logCPM values was plotted for both groups
  7728. using a kernel density plot to approximate a continuous distribution.
  7729. The logCPM GB distributions are marked in red, non-GB in blue.
  7730. The black vertical line denotes the chosen detection threshold of -1.
  7731. Top panel: Libraries were split into GB and non-GB groups first and normalized
  7732. separately.
  7733. Bottom panel: Libraries were all normalized together first and then split
  7734. into groups.
  7735. \end_layout
  7736. \end_inset
  7737. \end_layout
  7738. \begin_layout Plain Layout
  7739. \end_layout
  7740. \end_inset
  7741. \end_layout
  7742. \begin_layout Standard
  7743. Since globin blocking yields more usable sequencing depth, it should also
  7744. allow detection of more genes at any given threshold.
  7745. When we looked at the distribution of average normalized logCPM values
  7746. across all libraries for genes with at least one read assigned to them,
  7747. we observed the expected bimodal distribution, with a high-abundance "signal"
  7748. peak representing detected genes and a low-abundance "noise" peak representing
  7749. genes whose read count did not rise above the noise floor (Figure
  7750. \begin_inset CommandInset ref
  7751. LatexCommand ref
  7752. reference "fig:logcpm-dists"
  7753. plural "false"
  7754. caps "false"
  7755. noprefix "false"
  7756. \end_inset
  7757. ).
  7758. Consistent with the 2-fold increase in raw counts assigned to non-globin
  7759. genes, the signal peak for GB samples is shifted to the right relative
  7760. to the non-GB signal peak.
  7761. When all the samples are normalized together, this difference is normalized
  7762. out, lining up the signal peaks, and this reveals that, as expected, the
  7763. noise floor for the GB samples is about 2-fold lower.
  7764. This greater separation between signal and noise peaks in the GB samples
  7765. means that low-expression genes should be more easily detected and more
  7766. precisely quantified than in the non-GB samples.
  7767. \end_layout
  7768. \begin_layout Standard
  7769. \begin_inset Float figure
  7770. wide false
  7771. sideways false
  7772. status collapsed
  7773. \begin_layout Plain Layout
  7774. \align center
  7775. \begin_inset Graphics
  7776. filename graphics/Globin Paper/figure3 - detection.pdf
  7777. lyxscale 50
  7778. width 70col%
  7779. \end_inset
  7780. \end_layout
  7781. \begin_layout Plain Layout
  7782. \begin_inset Caption Standard
  7783. \begin_layout Plain Layout
  7784. \series bold
  7785. \begin_inset Argument 1
  7786. status collapsed
  7787. \begin_layout Plain Layout
  7788. Gene detections as a function of abundance thresholds in globin-blocked
  7789. (GB) and non-GB samples.
  7790. \end_layout
  7791. \end_inset
  7792. \begin_inset CommandInset label
  7793. LatexCommand label
  7794. name "fig:Gene-detections"
  7795. \end_inset
  7796. Gene detections as a function of abundance thresholds in globin-blocked
  7797. (GB) and non-GB samples.
  7798. \series default
  7799. Average abundance (logCPM,
  7800. \begin_inset Formula $\log_{2}$
  7801. \end_inset
  7802. counts per million reads counted) was computed by separate group normalization
  7803. as described in Figure
  7804. \begin_inset CommandInset ref
  7805. LatexCommand ref
  7806. reference "fig:logcpm-dists"
  7807. plural "false"
  7808. caps "false"
  7809. noprefix "false"
  7810. \end_inset
  7811. for both the GB and non-GB groups, as well as for all samples considered
  7812. as one large group.
  7813. For each every integer threshold from -2 to 3, the number of genes detected
  7814. at or above that logCPM threshold was plotted for each group.
  7815. \end_layout
  7816. \end_inset
  7817. \end_layout
  7818. \begin_layout Plain Layout
  7819. \end_layout
  7820. \end_inset
  7821. \end_layout
  7822. \begin_layout Standard
  7823. Based on these distributions, we selected a detection threshold of -1, which
  7824. is approximately the leftmost edge of the trough between the signal and
  7825. noise peaks.
  7826. This represents the most liberal possible detection threshold that doesn't
  7827. call substantial numbers of noise genes as detected.
  7828. Among the full dataset, 13429 genes were detected at this threshold, and
  7829. 22276 were not.
  7830. When considering the GB libraries and non-GB libraries separately and re-comput
  7831. ing normalization factors independently within each group, 14535 genes were
  7832. detected in the GB libraries while only 12460 were detected in the non-GB
  7833. libraries.
  7834. Thus, GB allowed the detection of 2000 extra genes that were buried under
  7835. the noise floor without GB.
  7836. This pattern of at least 2000 additional genes detected with GB was also
  7837. consistent across a wide range of possible detection thresholds, from -2
  7838. to 3 (see Figure
  7839. \begin_inset CommandInset ref
  7840. LatexCommand ref
  7841. reference "fig:Gene-detections"
  7842. plural "false"
  7843. caps "false"
  7844. noprefix "false"
  7845. \end_inset
  7846. ).
  7847. \end_layout
  7848. \begin_layout Subsection
  7849. Globin blocking does not add significant additional noise or decrease sample
  7850. quality
  7851. \end_layout
  7852. \begin_layout Standard
  7853. One potential worry is that the globin blocking protocol could perturb the
  7854. levels of non-globin genes.
  7855. There are two kinds of possible perturbations: systematic and random.
  7856. The former is not a major concern for detection of differential expression,
  7857. since a 2-fold change in every sample has no effect on the relative fold
  7858. change between samples.
  7859. In contrast, random perturbations would increase the noise and obscure
  7860. the signal in the dataset, reducing the capacity to detect differential
  7861. expression.
  7862. \end_layout
  7863. \begin_layout Standard
  7864. \begin_inset Float figure
  7865. wide false
  7866. sideways false
  7867. status collapsed
  7868. \begin_layout Plain Layout
  7869. \align center
  7870. \begin_inset Graphics
  7871. filename graphics/Globin Paper/figure4 - maplot-colored.pdf
  7872. lyxscale 50
  7873. width 100col%
  7874. groupId colwidth
  7875. \end_inset
  7876. \end_layout
  7877. \begin_layout Plain Layout
  7878. \begin_inset Caption Standard
  7879. \begin_layout Plain Layout
  7880. \begin_inset Argument 1
  7881. status collapsed
  7882. \begin_layout Plain Layout
  7883. MA plot showing effects of globin blocking on each gene's abundance.
  7884. \end_layout
  7885. \end_inset
  7886. \begin_inset CommandInset label
  7887. LatexCommand label
  7888. name "fig:MA-plot"
  7889. \end_inset
  7890. \series bold
  7891. MA plot showing effects of globin blocking on each gene's abundance.
  7892. \series default
  7893. All libraries were normalized together as described in Figure
  7894. \begin_inset CommandInset ref
  7895. LatexCommand ref
  7896. reference "fig:logcpm-dists"
  7897. plural "false"
  7898. caps "false"
  7899. noprefix "false"
  7900. \end_inset
  7901. , and genes with an average logCPM below -1 were filtered out.
  7902. Each remaining gene was tested for differential abundance with respect
  7903. to globin blocking (GB) using edgeR’s quasi-likelihod F-test, fitting a
  7904. negative binomial generalized linear model to table of read counts in each
  7905. library.
  7906. For each gene, edgeR reported average abundance (logCPM),
  7907. \begin_inset Formula $\log_{2}$
  7908. \end_inset
  7909. fold change (logFC), p-value, and Benjamini-Hochberg adjusted false discovery
  7910. rate (FDR).
  7911. Each gene's logFC was plotted against its logCPM, colored by FDR.
  7912. Red points are significant at ≤10% FDR, and blue are not significant at
  7913. that threshold.
  7914. The alpha and beta globin genes targeted for blocking are marked with large
  7915. triangles, while all other genes are represented as small points.
  7916. \end_layout
  7917. \end_inset
  7918. \end_layout
  7919. \begin_layout Plain Layout
  7920. \end_layout
  7921. \end_inset
  7922. \end_layout
  7923. \begin_layout Standard
  7924. \begin_inset Flex TODO Note (inline)
  7925. status open
  7926. \begin_layout Plain Layout
  7927. Standardize on
  7928. \begin_inset Quotes eld
  7929. \end_inset
  7930. log2
  7931. \begin_inset Quotes erd
  7932. \end_inset
  7933. notation
  7934. \end_layout
  7935. \end_inset
  7936. \end_layout
  7937. \begin_layout Standard
  7938. The data do indeed show small systematic perturbations in gene levels (Figure
  7939. \begin_inset CommandInset ref
  7940. LatexCommand ref
  7941. reference "fig:MA-plot"
  7942. plural "false"
  7943. caps "false"
  7944. noprefix "false"
  7945. \end_inset
  7946. ).
  7947. Other than the 3 designated alpha and beta globin genes, two other genes
  7948. stand out as having especially large negative log fold changes: HBD and
  7949. LOC1021365.
  7950. HBD, delta globin, is most likely targeted by the blocking oligos due to
  7951. high sequence homology with the other globin genes.
  7952. LOC1021365 is the aforementioned ncRNA that is reverse-complementary to
  7953. one of the alpha-like genes and that would be expected to be removed during
  7954. the globin blocking step.
  7955. All other genes appear in a cluster centered vertically at 0, and the vast
  7956. majority of genes in this cluster show an absolute log2(FC) of 0.5 or less.
  7957. Nevertheless, many of these small perturbations are still statistically
  7958. significant, indicating that the globin blocking oligos likely cause very
  7959. small but non-zero systematic perturbations in measured gene expression
  7960. levels.
  7961. \end_layout
  7962. \begin_layout Standard
  7963. \begin_inset Float figure
  7964. wide false
  7965. sideways false
  7966. status collapsed
  7967. \begin_layout Plain Layout
  7968. \align center
  7969. \begin_inset Graphics
  7970. filename graphics/Globin Paper/figure5 - corrplot.pdf
  7971. lyxscale 50
  7972. width 70col%
  7973. \end_inset
  7974. \end_layout
  7975. \begin_layout Plain Layout
  7976. \begin_inset Caption Standard
  7977. \begin_layout Plain Layout
  7978. \series bold
  7979. \begin_inset Argument 1
  7980. status collapsed
  7981. \begin_layout Plain Layout
  7982. Comparison of inter-sample gene abundance correlations with and without
  7983. globin blocking.
  7984. \end_layout
  7985. \end_inset
  7986. \begin_inset CommandInset label
  7987. LatexCommand label
  7988. name "fig:gene-abundance-correlations"
  7989. \end_inset
  7990. Comparison of inter-sample gene abundance correlations with and without
  7991. globin blocking (GB).
  7992. \series default
  7993. All libraries were normalized together as described in Figure 2, and genes
  7994. with an average abundance (logCPM, log2 counts per million reads counted)
  7995. less than -1 were filtered out.
  7996. Each gene’s logCPM was computed in each library using the edgeR cpm function.
  7997. For each pair of biological samples, the Pearson correlation between those
  7998. samples' GB libraries was plotted against the correlation between the same
  7999. samples’ non-GB libraries.
  8000. Each point represents an unique pair of samples.
  8001. The solid gray line shows a quantile-quantile plot of distribution of GB
  8002. correlations vs.
  8003. that of non-GB correlations.
  8004. The thin dashed line is the identity line, provided for reference.
  8005. \end_layout
  8006. \end_inset
  8007. \end_layout
  8008. \begin_layout Plain Layout
  8009. \end_layout
  8010. \end_inset
  8011. \end_layout
  8012. \begin_layout Standard
  8013. To evaluate the possibility of globin blocking causing random perturbations
  8014. and reducing sample quality, we computed the Pearson correlation between
  8015. logCPM values for every pair of samples with and without GB and plotted
  8016. them against each other (Figure
  8017. \begin_inset CommandInset ref
  8018. LatexCommand ref
  8019. reference "fig:gene-abundance-correlations"
  8020. plural "false"
  8021. caps "false"
  8022. noprefix "false"
  8023. \end_inset
  8024. ).
  8025. The plot indicated that the GB libraries have higher sample-to-sample correlati
  8026. ons than the non-GB libraries.
  8027. Parametric and nonparametric tests for differences between the correlations
  8028. with and without GB both confirmed that this difference was highly significant
  8029. (2-sided paired t-test: t = 37.2, df = 665, P ≪ 2.2e-16; 2-sided Wilcoxon
  8030. sign-rank test: V = 2195, P ≪ 2.2e-16).
  8031. Performing the same tests on the Spearman correlations gave the same conclusion
  8032. (t-test: t = 26.8, df = 665, P ≪ 2.2e-16; sign-rank test: V = 8781, P ≪ 2.2e-16).
  8033. The edgeR package was used to compute the overall biological coefficient
  8034. of variation (BCV) for GB and non-GB libraries, and found that globin blocking
  8035. resulted in a negligible increase in the BCV (0.417 with GB vs.
  8036. 0.400 without).
  8037. The near equality of the BCVs for both sets indicates that the higher correlati
  8038. ons in the GB libraries are most likely a result of the increased yield
  8039. of useful reads, which reduces the contribution of Poisson counting uncertainty
  8040. to the overall variance of the logCPM values
  8041. \begin_inset CommandInset citation
  8042. LatexCommand cite
  8043. key "McCarthy2012"
  8044. literal "false"
  8045. \end_inset
  8046. .
  8047. This improves the precision of expression measurements and more than offsets
  8048. the negligible increase in BCV.
  8049. \end_layout
  8050. \begin_layout Subsection
  8051. More differentially expressed genes are detected with globin blocking
  8052. \end_layout
  8053. \begin_layout Standard
  8054. \begin_inset Float table
  8055. wide false
  8056. sideways false
  8057. status collapsed
  8058. \begin_layout Plain Layout
  8059. \align center
  8060. \begin_inset Tabular
  8061. <lyxtabular version="3" rows="5" columns="5">
  8062. <features tabularvalignment="middle">
  8063. <column alignment="center" valignment="top">
  8064. <column alignment="center" valignment="top">
  8065. <column alignment="center" valignment="top">
  8066. <column alignment="center" valignment="top">
  8067. <column alignment="center" valignment="top">
  8068. <row>
  8069. <cell alignment="center" valignment="top" usebox="none">
  8070. \begin_inset Text
  8071. \begin_layout Plain Layout
  8072. \end_layout
  8073. \end_inset
  8074. </cell>
  8075. <cell alignment="center" valignment="top" usebox="none">
  8076. \begin_inset Text
  8077. \begin_layout Plain Layout
  8078. \end_layout
  8079. \end_inset
  8080. </cell>
  8081. <cell multicolumn="1" alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  8082. \begin_inset Text
  8083. \begin_layout Plain Layout
  8084. \series bold
  8085. No Globin Blocking
  8086. \end_layout
  8087. \end_inset
  8088. </cell>
  8089. <cell multicolumn="2" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  8090. \begin_inset Text
  8091. \begin_layout Plain Layout
  8092. \end_layout
  8093. \end_inset
  8094. </cell>
  8095. <cell multicolumn="2" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  8096. \begin_inset Text
  8097. \begin_layout Plain Layout
  8098. \end_layout
  8099. \end_inset
  8100. </cell>
  8101. </row>
  8102. <row>
  8103. <cell alignment="center" valignment="top" usebox="none">
  8104. \begin_inset Text
  8105. \begin_layout Plain Layout
  8106. \end_layout
  8107. \end_inset
  8108. </cell>
  8109. <cell alignment="center" valignment="top" usebox="none">
  8110. \begin_inset Text
  8111. \begin_layout Plain Layout
  8112. \end_layout
  8113. \end_inset
  8114. </cell>
  8115. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8116. \begin_inset Text
  8117. \begin_layout Plain Layout
  8118. \series bold
  8119. Up
  8120. \end_layout
  8121. \end_inset
  8122. </cell>
  8123. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8124. \begin_inset Text
  8125. \begin_layout Plain Layout
  8126. \series bold
  8127. NS
  8128. \end_layout
  8129. \end_inset
  8130. </cell>
  8131. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  8132. \begin_inset Text
  8133. \begin_layout Plain Layout
  8134. \series bold
  8135. Down
  8136. \end_layout
  8137. \end_inset
  8138. </cell>
  8139. </row>
  8140. <row>
  8141. <cell multirow="3" alignment="center" valignment="middle" topline="true" bottomline="true" leftline="true" usebox="none">
  8142. \begin_inset Text
  8143. \begin_layout Plain Layout
  8144. \series bold
  8145. Globin-Blocking
  8146. \end_layout
  8147. \end_inset
  8148. </cell>
  8149. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8150. \begin_inset Text
  8151. \begin_layout Plain Layout
  8152. \series bold
  8153. Up
  8154. \end_layout
  8155. \end_inset
  8156. </cell>
  8157. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8158. \begin_inset Text
  8159. \begin_layout Plain Layout
  8160. \family roman
  8161. \series medium
  8162. \shape up
  8163. \size normal
  8164. \emph off
  8165. \bar no
  8166. \strikeout off
  8167. \xout off
  8168. \uuline off
  8169. \uwave off
  8170. \noun off
  8171. \color none
  8172. 231
  8173. \end_layout
  8174. \end_inset
  8175. </cell>
  8176. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8177. \begin_inset Text
  8178. \begin_layout Plain Layout
  8179. \family roman
  8180. \series medium
  8181. \shape up
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  8184. \bar no
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  8190. \color none
  8191. 515
  8192. \end_layout
  8193. \end_inset
  8194. </cell>
  8195. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  8196. \begin_inset Text
  8197. \begin_layout Plain Layout
  8198. \family roman
  8199. \series medium
  8200. \shape up
  8201. \size normal
  8202. \emph off
  8203. \bar no
  8204. \strikeout off
  8205. \xout off
  8206. \uuline off
  8207. \uwave off
  8208. \noun off
  8209. \color none
  8210. 2
  8211. \end_layout
  8212. \end_inset
  8213. </cell>
  8214. </row>
  8215. <row>
  8216. <cell multirow="4" alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8217. \begin_inset Text
  8218. \begin_layout Plain Layout
  8219. \end_layout
  8220. \end_inset
  8221. </cell>
  8222. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8223. \begin_inset Text
  8224. \begin_layout Plain Layout
  8225. \series bold
  8226. NS
  8227. \end_layout
  8228. \end_inset
  8229. </cell>
  8230. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8231. \begin_inset Text
  8232. \begin_layout Plain Layout
  8233. \family roman
  8234. \series medium
  8235. \shape up
  8236. \size normal
  8237. \emph off
  8238. \bar no
  8239. \strikeout off
  8240. \xout off
  8241. \uuline off
  8242. \uwave off
  8243. \noun off
  8244. \color none
  8245. 160
  8246. \end_layout
  8247. \end_inset
  8248. </cell>
  8249. <cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
  8250. \begin_inset Text
  8251. \begin_layout Plain Layout
  8252. \family roman
  8253. \series medium
  8254. \shape up
  8255. \size normal
  8256. \emph off
  8257. \bar no
  8258. \strikeout off
  8259. \xout off
  8260. \uuline off
  8261. \uwave off
  8262. \noun off
  8263. \color none
  8264. 11235
  8265. \end_layout
  8266. \end_inset
  8267. </cell>
  8268. <cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
  8269. \begin_inset Text
  8270. \begin_layout Plain Layout
  8271. \family roman
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  8273. \shape up
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  8275. \emph off
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  8279. \uuline off
  8280. \uwave off
  8281. \noun off
  8282. \color none
  8283. 136
  8284. \end_layout
  8285. \end_inset
  8286. </cell>
  8287. </row>
  8288. <row>
  8289. <cell multirow="4" alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  8290. \begin_inset Text
  8291. \begin_layout Plain Layout
  8292. \end_layout
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  8294. </cell>
  8295. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  8296. \begin_inset Text
  8297. \begin_layout Plain Layout
  8298. \series bold
  8299. Down
  8300. \end_layout
  8301. \end_inset
  8302. </cell>
  8303. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  8304. \begin_inset Text
  8305. \begin_layout Plain Layout
  8306. \family roman
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  8316. \noun off
  8317. \color none
  8318. 0
  8319. \end_layout
  8320. \end_inset
  8321. </cell>
  8322. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
  8323. \begin_inset Text
  8324. \begin_layout Plain Layout
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  8336. \color none
  8337. 548
  8338. \end_layout
  8339. \end_inset
  8340. </cell>
  8341. <cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
  8342. \begin_inset Text
  8343. \begin_layout Plain Layout
  8344. \family roman
  8345. \series medium
  8346. \shape up
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  8348. \emph off
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  8355. \color none
  8356. 127
  8357. \end_layout
  8358. \end_inset
  8359. </cell>
  8360. </row>
  8361. </lyxtabular>
  8362. \end_inset
  8363. \end_layout
  8364. \begin_layout Plain Layout
  8365. \begin_inset Caption Standard
  8366. \begin_layout Plain Layout
  8367. \series bold
  8368. \begin_inset Argument 1
  8369. status open
  8370. \begin_layout Plain Layout
  8371. Comparison of significantly differentially expressed genes with and without
  8372. globin blocking.
  8373. \end_layout
  8374. \end_inset
  8375. \begin_inset CommandInset label
  8376. LatexCommand label
  8377. name "tab:Comparison-of-significant"
  8378. \end_inset
  8379. Comparison of significantly differentially expressed genes with and without
  8380. globin blocking.
  8381. \series default
  8382. Up, Down: Genes significantly up/down-regulated in post-transplant samples
  8383. relative to pre-transplant samples, with a false discovery rate of 10%
  8384. or less.
  8385. NS: Non-significant genes (false discovery rate greater than 10%).
  8386. \end_layout
  8387. \end_inset
  8388. \end_layout
  8389. \begin_layout Plain Layout
  8390. \end_layout
  8391. \end_inset
  8392. \end_layout
  8393. \begin_layout Standard
  8394. To compare performance on differential gene expression tests, we took subsets
  8395. of both the GB and non-GB libraries with exactly one pre-transplant and
  8396. one post-transplant sample for each animal that had paired samples available
  8397. for analysis (N=7 animals, N=14 samples in each subset).
  8398. The same test for pre- vs.
  8399. post-transplant differential gene expression was performed on the same
  8400. 7 pairs of samples from GB libraries and non-GB libraries, in each case
  8401. using an FDR of 10% as the threshold of significance.
  8402. Out of 12954 genes that passed the detection threshold in both subsets,
  8403. 358 were called significantly differentially expressed in the same direction
  8404. in both sets; 1063 were differentially expressed in the GB set only; 296
  8405. were differentially expressed in the non-GB set only; 2 genes were called
  8406. significantly up in the GB set but significantly down in the non-GB set;
  8407. and the remaining 11235 were not called differentially expressed in either
  8408. set.
  8409. These data are summarized in Table
  8410. \begin_inset CommandInset ref
  8411. LatexCommand ref
  8412. reference "tab:Comparison-of-significant"
  8413. plural "false"
  8414. caps "false"
  8415. noprefix "false"
  8416. \end_inset
  8417. .
  8418. The differences in BCV calculated by EdgeR for these subsets of samples
  8419. were negligible (BCV = 0.302 for GB and 0.297 for non-GB).
  8420. \end_layout
  8421. \begin_layout Standard
  8422. The key point is that the GB data results in substantially more differentially
  8423. expressed calls than the non-GB data.
  8424. Since there is no gold standard for this dataset, it is impossible to be
  8425. certain whether this is due to under-calling of differential expression
  8426. in the non-GB samples or over-calling in the GB samples.
  8427. However, given that both datasets are derived from the same biological
  8428. samples and have nearly equal BCVs, it is more likely that the larger number
  8429. of DE calls in the GB samples are genuine detections that were enabled
  8430. by the higher sequencing depth and measurement precision of the GB samples.
  8431. Note that the same set of genes was considered in both subsets, so the
  8432. larger number of differentially expressed gene calls in the GB data set
  8433. reflects a greater sensitivity to detect significant differential gene
  8434. expression and not simply the larger total number of detected genes in
  8435. GB samples described earlier.
  8436. \end_layout
  8437. \begin_layout Section
  8438. Discussion
  8439. \end_layout
  8440. \begin_layout Standard
  8441. The original experience with whole blood gene expression profiling on DNA
  8442. microarrays demonstrated that the high concentration of globin transcripts
  8443. reduced the sensitivity to detect genes with relatively low expression
  8444. levels, in effect, significantly reducing the sensitivity.
  8445. To address this limitation, commercial protocols for globin reduction were
  8446. developed based on strategies to block globin transcript amplification
  8447. during labeling or physically removing globin transcripts by affinity bead
  8448. methods
  8449. \begin_inset CommandInset citation
  8450. LatexCommand cite
  8451. key "Winn2010"
  8452. literal "false"
  8453. \end_inset
  8454. .
  8455. More recently, using the latest generation of labeling protocols and arrays,
  8456. it was determined that globin reduction was no longer necessary to obtain
  8457. sufficient sensitivity to detect differential transcript expression
  8458. \begin_inset CommandInset citation
  8459. LatexCommand cite
  8460. key "NuGEN2010"
  8461. literal "false"
  8462. \end_inset
  8463. .
  8464. However, we are not aware of any publications using these currently available
  8465. protocols the with latest generation of microarrays that actually compare
  8466. the detection sensitivity with and without globin reduction.
  8467. However, in practice this has now been adopted generally primarily driven
  8468. by concerns for cost control.
  8469. The main objective of our work was to directly test the impact of globin
  8470. gene transcripts and a new globin blocking protocol for application to
  8471. the newest generation of differential gene expression profiling determined
  8472. using next generation sequencing.
  8473. \end_layout
  8474. \begin_layout Standard
  8475. The challenge of doing global gene expression profiling in cynomolgus monkeys
  8476. is that the current available arrays were never designed to comprehensively
  8477. cover this genome and have not been updated since the first assemblies
  8478. of the cynomolgus genome were published.
  8479. Therefore, we determined that the best strategy for peripheral blood profiling
  8480. was to do deep RNA-seq and inform the workflow using the latest available
  8481. genome assembly and annotation
  8482. \begin_inset CommandInset citation
  8483. LatexCommand cite
  8484. key "Wilson2013"
  8485. literal "false"
  8486. \end_inset
  8487. .
  8488. However, it was not immediately clear whether globin reduction was necessary
  8489. for RNA-seq or how much improvement in efficiency or sensitivity to detect
  8490. differential gene expression would be achieved for the added cost and work.
  8491. \end_layout
  8492. \begin_layout Standard
  8493. We only found one report that demonstrated that globin reduction significantly
  8494. improved the effective read yields for sequencing of human peripheral blood
  8495. cell RNA using a DeepSAGE protocol
  8496. \begin_inset CommandInset citation
  8497. LatexCommand cite
  8498. key "Mastrokolias2012"
  8499. literal "false"
  8500. \end_inset
  8501. .
  8502. The approach to DeepSAGE involves two different restriction enzymes that
  8503. purify and then tag small fragments of transcripts at specific locations
  8504. and thus, significantly reduces the complexity of the transcriptome.
  8505. Therefore, we could not determine how DeepSAGE results would translate
  8506. to the common strategy in the field for assaying the entire transcript
  8507. population by whole-transcriptome 3’-end RNA-seq.
  8508. Furthermore, if globin reduction is necessary, we also needed a globin
  8509. reduction method specific to cynomolgus globin sequences that would work
  8510. an organism for which no kit is available off the shelf.
  8511. \end_layout
  8512. \begin_layout Standard
  8513. As mentioned above, the addition of globin blocking oligos has a very small
  8514. impact on measured expression levels of gene expression.
  8515. However, this is a non-issue for the purposes of differential expression
  8516. testing, since a systematic change in a gene in all samples does not affect
  8517. relative expression levels between samples.
  8518. However, we must acknowledge that simple comparisons of gene expression
  8519. data obtained by GB and non-GB protocols are not possible without additional
  8520. normalization.
  8521. \end_layout
  8522. \begin_layout Standard
  8523. More importantly, globin blocking not only nearly doubles the yield of usable
  8524. reads, it also increases inter-sample correlation and sensitivity to detect
  8525. differential gene expression relative to the same set of samples profiled
  8526. without blocking.
  8527. In addition, globin blocking does not add a significant amount of random
  8528. noise to the data.
  8529. Globin blocking thus represents a cost-effective way to squeeze more data
  8530. and statistical power out of the same blood samples and the same amount
  8531. of sequencing.
  8532. In conclusion, globin reduction greatly increases the yield of useful RNA-seq
  8533. reads mapping to the rest of the genome, with minimal perturbations in
  8534. the relative levels of non-globin genes.
  8535. Based on these results, globin transcript reduction using sequence-specific,
  8536. complementary blocking oligonucleotides is recommended for all deep RNA-seq
  8537. of cynomolgus and other nonhuman primate blood samples.
  8538. \end_layout
  8539. \begin_layout Chapter
  8540. Future Directions
  8541. \end_layout
  8542. \begin_layout Standard
  8543. \begin_inset Flex TODO Note (inline)
  8544. status open
  8545. \begin_layout Plain Layout
  8546. Consider per-chapter future directions.
  8547. Check instructions.
  8548. \end_layout
  8549. \end_inset
  8550. \end_layout
  8551. \begin_layout Itemize
  8552. Functional validation of effective promoter radius
  8553. \end_layout
  8554. \begin_layout Itemize
  8555. N-to-M convergence deserves further stufy of some kind
  8556. \end_layout
  8557. \begin_layout Itemize
  8558. Promoter positional coverage: follow up on hints of interesting patterns
  8559. \end_layout
  8560. \begin_layout Itemize
  8561. Study other epigenetic marks in more contexts
  8562. \end_layout
  8563. \begin_deeper
  8564. \begin_layout Itemize
  8565. DNA methylation, histone marks, chromatin accessibility & conformation in
  8566. CD4 T-cells
  8567. \end_layout
  8568. \begin_layout Itemize
  8569. Also look at other types of lymphocytes: CD8 T-cells, B-cells, NK cells
  8570. \end_layout
  8571. \end_deeper
  8572. \begin_layout Itemize
  8573. Use CV or bootstrap to better evaluate classifiers
  8574. \end_layout
  8575. \begin_layout Itemize
  8576. fRMAtools could be adapted to not require equal-sized groups
  8577. \end_layout
  8578. \begin_layout Standard
  8579. \begin_inset ERT
  8580. status open
  8581. \begin_layout Plain Layout
  8582. % Call it "References" instead of "Bibliography"
  8583. \end_layout
  8584. \begin_layout Plain Layout
  8585. \backslash
  8586. renewcommand{
  8587. \backslash
  8588. bibname}{References}
  8589. \end_layout
  8590. \end_inset
  8591. \end_layout
  8592. \begin_layout Standard
  8593. \begin_inset Flex TODO Note (inline)
  8594. status open
  8595. \begin_layout Plain Layout
  8596. Check bib entry formatting & sort order
  8597. \end_layout
  8598. \end_inset
  8599. \end_layout
  8600. \begin_layout Standard
  8601. \begin_inset Flex TODO Note (inline)
  8602. status open
  8603. \begin_layout Plain Layout
  8604. Check in-text citation format.
  8605. Probably don't just want [1], [2], etc.
  8606. \end_layout
  8607. \end_inset
  8608. \end_layout
  8609. \begin_layout Standard
  8610. \begin_inset CommandInset bibtex
  8611. LatexCommand bibtex
  8612. btprint "btPrintCited"
  8613. bibfiles "code-refs,refs-PROCESSED"
  8614. options "bibtotoc,unsrt"
  8615. \end_inset
  8616. \end_layout
  8617. \end_body
  8618. \end_document