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@@ -1545,10 +1545,298 @@ literal "false"
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Then, the ratios were transformed to M-values.
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\end_layout
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+\begin_inset Caption Standard
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+
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+\begin_layout Plain Layout
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+
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+\series bold
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+\begin_inset CommandInset label
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+LatexCommand label
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+name "tab:Summary-of-meth-analysis"
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+
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+\end_inset
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+
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+Summary of analysis variants for methylation array data.
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+
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+\series default
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+Each analysis included a different set of steps to adjust or account for
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+ various systematic features of the data.
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+ See the text for a more detailed explanation of each step.
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+\end_layout
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+\end_inset
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+
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\begin_layout Standard
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From the M-values, a series of parallel analyses was performed, each adding
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- additional steps into the model fit to accomodate a feature of the data.
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- First, a
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+ additional steps into the model fit to accomodate a feature of the data
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+ (see Table
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+\begin_inset CommandInset ref
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+LatexCommand ref
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+reference "tab:Summary-of-meth-analysis"
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+plural "false"
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+caps "false"
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+noprefix "false"
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+
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+\end_inset
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+
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+).
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+ For analysis A, a
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\begin_inset Quotes eld
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\end_inset
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@@ -1556,13 +1844,12 @@ basic
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\begin_inset Quotes erd
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\end_inset
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- linear modeling analysis was performed, compensating for known features
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- of the data using existing tools.
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- A design matrix was prepared including terms for the factor of interest
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- as well as the known biological confounders: sex, age, ethnicity, and diabetes.
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- Since some samples came from the same patients at differen times, the intra-pat
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-ient correlation was modeled as a random effect, estimating a shared correlation
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- value across all probes
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+ linear modeling analysis was performed, compensating for known confounders
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+ by including terms for the factor of interest (transplant status) as well
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+ as the known biological confounders: sex, age, ethnicity, and diabetes.
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+ Since some samples came from the same patients at different times, the
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+ intra-patient correlation was modeled as a random effect, estimating a
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+ shared correlation value across all probes
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\begin_inset CommandInset citation
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LatexCommand cite
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key "Smyth2005a"
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@@ -1581,12 +1868,22 @@ literal "false"
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\end_inset
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.
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- Finally, t-tests or F-tests were performed a appropriate for each test:
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+ Finally, t-tests or F-tests were performed as appropriate for each test:
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t-tests for single contrasts, and F-tests for multiple contrasts.
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+ P-values were corrected for multiple testing using the Benjamini-Hochberg
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+ procedure for FDR control
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+\begin_inset CommandInset citation
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+LatexCommand cite
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+key "Benjamini1995"
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+literal "false"
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+
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+\end_inset
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+
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+.
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\end_layout
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\begin_layout Standard
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-For the second analysis, surrogate variable analysis (SVA) was used to infer
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+For the analysis B, surrogate variable analysis (SVA) was used to infer
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additional unobserved sources of heterogeneity in the data
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\begin_inset CommandInset citation
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LatexCommand cite
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@@ -1609,9 +1906,10 @@ literal "false"
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\end_inset
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.
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- For the third analysis, the voom method was adapted to run on methylation
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- array data and used to model the mean-variance trend as individual observation
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- weights
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+ The remainder of the analysis proceeded as in analysis A.
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+ For analysis C, the voom method was adapted to run on methylation array
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+ data and used to model and correct for the mean-variance trend using individual
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+ observation weights
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\begin_inset CommandInset citation
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LatexCommand cite
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key "Law2013"
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@@ -1631,6 +1929,7 @@ literal "false"
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Each time weights were used, they were estimated once before estimating
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the random effect correlation value, and then the weights were re-estimated
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taking the random effect into account.
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+ The remainder of the analysis proceeded as in analysis B.
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\end_layout
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\begin_layout Section
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@@ -1655,6 +1954,19 @@ fRMA eliminates unwanted dependence of classifier training on normalization
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strategy caused by RMA
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\end_layout
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+\begin_layout Standard
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+\begin_inset Flex TODO Note (inline)
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+status open
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+
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+\begin_layout Plain Layout
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+Write figure legends
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+\end_layout
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+
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+\end_inset
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+
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+
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+\end_layout
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+
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\begin_layout Subsubsection
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Separate normalization with RMA introduces unwanted biases in classification
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\end_layout
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@@ -1663,7 +1975,7 @@ Separate normalization with RMA introduces unwanted biases in classification
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\begin_inset Float figure
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -1705,10 +2017,10 @@ Classifier probabilities on validation samples when normalized with RMA
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\end_layout
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\begin_layout Standard
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-To demonstrate the problem with non-single-channel methods, we considered
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- the problem of training a classifier to distinguish TX from AR using the
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- samples from the internal set as training data, evaluating performance
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- on the external set.
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+To demonstrate the problem with non-single-channel normalization methods,
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+ we considered the problem of training a classifier to distinguish TX from
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+ AR using the samples from the internal set as training data, evaluating
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+ performance on the external set.
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First, training and evaluation were performed after normalizing all array
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samples together as a single set using RMA, and second, the internal samples
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were normalized separately from the external samples and the training and
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@@ -1761,6 +2073,8 @@ status collapsed
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\begin_inset Caption Standard
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\begin_layout Plain Layout
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+
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+\series bold
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\begin_inset CommandInset label
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LatexCommand label
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name "fig:ROC-PAM-int"
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@@ -2399,7 +2713,7 @@ noprefix "false"
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placement tb
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -2417,6 +2731,8 @@ status open
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\begin_inset Caption Standard
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\begin_layout Plain Layout
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+
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+\series bold
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\begin_inset CommandInset label
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LatexCommand label
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name "fig:ROC-PAM-ext"
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@@ -2498,7 +2814,7 @@ fRMA with custom-generated vectors enables normalization on hthgu133pluspm
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placement tb
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -2546,7 +2862,7 @@ For batch sizes ranging from 3 to 15, the number of batches with at least
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placement tb
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -2659,7 +2975,7 @@ literal "false"
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\begin_inset Float figure
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -2741,7 +3057,7 @@ noprefix "false"
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\begin_inset Float figure
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -2791,7 +3107,7 @@ Averages and log ratios were computed for every probe in each of 20 biopsy
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\begin_inset Float figure
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -2936,7 +3252,7 @@ noprefix "false"
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\begin_inset Float figure
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -2986,7 +3302,7 @@ Each of 20 randomly selected blood samples was normalized with RMA and with
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\begin_inset Float figure
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -3040,7 +3356,7 @@ Averages and log ratios were computed for every probe in each of 20 blood
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\begin_inset Float figure
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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@@ -3104,15 +3420,30 @@ FloatBarrier
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\end_layout
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|
\begin_layout Subsection
|
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|
-Adapting voom to methylation array data improves model fit
|
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+SVA, voom, and array weights improve model fit for methylation array data
|
|
|
\end_layout
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\begin_layout Standard
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+\begin_inset Float figure
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+wide false
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+sideways false
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+status collapsed
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+
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+\begin_layout Plain Layout
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+\align center
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\begin_inset Flex TODO Note (inline)
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status open
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\begin_layout Plain Layout
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-Write figure legends
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+Fix axis labels:
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+\begin_inset Quotes eld
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+\end_inset
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+
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+log2 M-value
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+\begin_inset Quotes erd
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+\end_inset
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+
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+ is redundant because M-values are already log scale
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\end_layout
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\end_inset
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@@ -3120,15 +3451,10 @@ Write figure legends
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\end_layout
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-\begin_layout Standard
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-\begin_inset Float figure
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-wide false
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-sideways false
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-status open
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-
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\begin_layout Plain Layout
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+\align center
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\begin_inset Graphics
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- filename graphics/methylvoom/unadj.dupcor/meanvar-trends-PAGE1-RASTER.png
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+ filename graphics/methylvoom/unadj.dupcor/meanvar-trends-PAGE1-CROP-RASTER.png
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lyxscale 15
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width 100col%
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groupId raster-600ppi
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@@ -3150,7 +3476,15 @@ name "fig:meanvar-basic"
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\end_inset
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-Mean-variance trend with no SVA or weights
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+Mean-variance trend for analysis A.
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+
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+\series default
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+The log2(standard deviation) for each probe is plotted against the probe's
|
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+ average M-value across all samples as a black point, with some transparency
|
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+ to make overplotting more visible, since there are about 450,000 points.
|
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+ Density of points is also indicated by the dark blue contour lines.
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+ The prior variance trend estimated by eBayes is shown in light blue, while
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+ the lowess trend of the points is shown in red.
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\end_layout
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\end_inset
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@@ -3163,6 +3497,50 @@ Mean-variance trend with no SVA or weights
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\end_layout
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+\begin_layout Standard
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+Figure
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+\begin_inset CommandInset ref
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+LatexCommand ref
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+reference "fig:meanvar-basic"
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+plural "false"
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+caps "false"
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+noprefix "false"
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+
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+\end_inset
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+
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+ shows the relationship between the mean M-value and the standard deviation
|
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+ calculated for each probe in the methylation array data set.
|
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|
+ A few features of the data are apparent.
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+ First, the data are very strongly bimodal, with peaks in the density around
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+ M-values of +4 and -4.
|
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+ These modes correspond to methylation sites that are nearly 100% methylated
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+ and nearly 100% unmethylated, respectively.
|
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+ The strong bomodality indicates that a majority of probes interrogate sites
|
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+ that fall into one of these two categories.
|
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+ The points in between these modes represent sites that are either partially
|
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|
+ methylated in many samples, or are fully methylated in some samples and
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|
+ fully unmethylated in other samples, or some combination.
|
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+ The next visible feature of the data is the W-shaped variance trend.
|
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+ The upticks in the variance trend on either side are expected, based on
|
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+ the sigmoid transformation exaggerating small differences at extreme M-values
|
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+ (Figure
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|
+\begin_inset CommandInset ref
|
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|
+LatexCommand ref
|
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|
+reference "fig:Sigmoid-beta-m-mapping"
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+plural "false"
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+caps "false"
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+noprefix "false"
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+
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+\end_inset
|
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+
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+).
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+ However, the uptick in the center is interesting: it indicates that sites
|
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|
+ that are not constitutitively methylated or unmethylated have a higher
|
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|
+ variance.
|
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|
+ This could be a genuine biological effect, or it could be spurious noise
|
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|
+ that is only observable at sites with varying methylation.
|
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|
+\end_layout
|
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+
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|
\begin_layout Standard
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\begin_inset Float figure
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wide false
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|
@@ -3171,7 +3549,7 @@ status open
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|
\begin_layout Plain Layout
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|
\begin_inset Graphics
|
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|
- filename graphics/methylvoom/unadj.dupcor.sva.aw/meanvar-trends-PAGE1-RASTER.png
|
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|
+ filename graphics/methylvoom/unadj.dupcor.sva.aw/meanvar-trends-PAGE1-CROP-RASTER.png
|
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|
lyxscale 15
|
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|
width 100col%
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|
groupId raster-600ppi
|
|
@@ -3193,12 +3571,20 @@ name "fig:meanvar-sva-aw"
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|
\end_inset
|
|
|
|
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|
-Mean-variance trend with SVA and sample quality weights.
|
|
|
-\end_layout
|
|
|
+Mean-variance trend for analysis B.
|
|
|
+
|
|
|
+\series default
|
|
|
+Interpretation is as in Figure
|
|
|
+\begin_inset CommandInset ref
|
|
|
+LatexCommand ref
|
|
|
+reference "fig:meanvar-basic"
|
|
|
+plural "false"
|
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|
+caps "false"
|
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|
+noprefix "false"
|
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|
\end_inset
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-
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|
+.
|
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|
\end_layout
|
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|
\end_inset
|
|
@@ -3206,59 +3592,57 @@ Mean-variance trend with SVA and sample quality weights.
|
|
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|
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|
\end_layout
|
|
|
|
|
|
-\begin_layout Standard
|
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|
-\begin_inset Float figure
|
|
|
-wide false
|
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|
-sideways false
|
|
|
-status open
|
|
|
-
|
|
|
-\begin_layout Plain Layout
|
|
|
-\begin_inset Graphics
|
|
|
- filename graphics/methylvoom/unadj.dupcor.sva.voomaw/meanvar-trends-PAGE1-RASTER.png
|
|
|
- lyxscale 15
|
|
|
- width 100col%
|
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|
- groupId raster-600ppi
|
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|
-
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|
\end_inset
|
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|
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|
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|
\end_layout
|
|
|
|
|
|
-\begin_layout Plain Layout
|
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|
-\begin_inset Caption Standard
|
|
|
-
|
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|
-\begin_layout Plain Layout
|
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|
-
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|
-\series bold
|
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|
-\begin_inset CommandInset label
|
|
|
-LatexCommand label
|
|
|
-name "fig:voom-sva-voomaw"
|
|
|
+\begin_layout Standard
|
|
|
+In Figure
|
|
|
+\begin_inset CommandInset ref
|
|
|
+LatexCommand ref
|
|
|
+reference "fig:meanvar-sva-aw"
|
|
|
+plural "false"
|
|
|
+caps "false"
|
|
|
+noprefix "false"
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
-Mean-variance trend modelled by voom, with SVA and sample weights.
|
|
|
-
|
|
|
-\series default
|
|
|
-The y-axis is the square root of the standard deviation for each probe,
|
|
|
- because this is the scale on which voom fits its lowess curve.
|
|
|
-\end_layout
|
|
|
-
|
|
|
+, we see the mean-variance trend for the same methylation array data, this
|
|
|
+ time with surrogate variables and sample quality weights estimated from
|
|
|
+ the data and included in the model.
|
|
|
+ As expected, the overall average variance is smaller, since the surrogate
|
|
|
+ variables account for some of the variance.
|
|
|
+ In addition, the uptick in variance in the middle of the M-value range
|
|
|
+ has disappeared, turning the W shape into a wide U shape.
|
|
|
+ This indicates that the excess variance in the probes with intermediate
|
|
|
+ M-values was explained by systematic variations not correlated with known
|
|
|
+ covariates, and these variations were modeled by the surrogate variables.
|
|
|
+ The result is a nearly flat variance trend for the entire intermediate
|
|
|
+ M-value range from about -3 to +3.
|
|
|
+ In contrast, the excess variance at the extremes was not
|
|
|
+\begin_inset Quotes eld
|
|
|
\end_inset
|
|
|
|
|
|
-
|
|
|
-\end_layout
|
|
|
-
|
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|
+absorbed
|
|
|
+\begin_inset Quotes erd
|
|
|
\end_inset
|
|
|
|
|
|
+ by the surrogate variables and remains in the plot, indicating that this
|
|
|
+ variation has no systematic component: probes with extreme M-values are
|
|
|
+ uniformly more variable across all samples, as expected.
|
|
|
+
|
|
|
+\end_layout
|
|
|
|
|
|
+\begin_layout Standard
|
|
|
\begin_inset Float figure
|
|
|
wide false
|
|
|
sideways false
|
|
|
-status open
|
|
|
+status collapsed
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
\begin_inset Graphics
|
|
|
- filename graphics/methylvoom/unadj.dupcor.sva.voomaw/meanvar-trends-PAGE2-RASTER.png
|
|
|
+ filename graphics/methylvoom/unadj.dupcor.sva.voomaw/meanvar-trends-PAGE2-CROP-RASTER.png
|
|
|
lyxscale 15
|
|
|
width 100col%
|
|
|
groupId raster-600ppi
|
|
@@ -3280,8 +3664,20 @@ name "fig:meanvar-sva-voomaw"
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
-Residual mean-variance trend after modeling with SVA, sample weights, and
|
|
|
- voom.
|
|
|
+Mean-variance trend after voom modeling in analysis C.
|
|
|
+
|
|
|
+\series default
|
|
|
+Interpretation is as in Figure
|
|
|
+\begin_inset CommandInset ref
|
|
|
+LatexCommand ref
|
|
|
+reference "fig:meanvar-basic"
|
|
|
+plural "false"
|
|
|
+caps "false"
|
|
|
+noprefix "false"
|
|
|
+
|
|
|
+\end_inset
|
|
|
+
|
|
|
+.
|
|
|
\end_layout
|
|
|
|
|
|
\end_inset
|
|
@@ -3294,42 +3690,55 @@ Residual mean-variance trend after modeling with SVA, sample weights, and
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Itemize
|
|
|
-U-shaped mean-var trend visible in data, even after accounting for unobserved
|
|
|
- confounders (SVA) and array quality (sample weights)
|
|
|
-\end_layout
|
|
|
+\begin_layout Standard
|
|
|
+Figure
|
|
|
+\begin_inset CommandInset ref
|
|
|
+LatexCommand ref
|
|
|
+reference "fig:meanvar-sva-voomaw"
|
|
|
+plural "false"
|
|
|
+caps "false"
|
|
|
+noprefix "false"
|
|
|
|
|
|
-\begin_layout Itemize
|
|
|
-\begin_inset Quotes eld
|
|
|
\end_inset
|
|
|
|
|
|
-vooma
|
|
|
-\begin_inset Quotes erd
|
|
|
-\end_inset
|
|
|
+ shows the mean-variance trend after fitting the model with the observation
|
|
|
+ weights assigned by voom based on the mean-variance trend shown in Figure
|
|
|
+
|
|
|
+\begin_inset CommandInset ref
|
|
|
+LatexCommand ref
|
|
|
+reference "fig:meanvar-sva-aw"
|
|
|
+plural "false"
|
|
|
+caps "false"
|
|
|
+noprefix "false"
|
|
|
|
|
|
- models this trend, and after voom, the mean-variance trend is flat and
|
|
|
- the median varaiance is approximately 1 (0 on log scale)
|
|
|
-\end_layout
|
|
|
+\end_inset
|
|
|
|
|
|
-\begin_layout Itemize
|
|
|
-M-value distribution is bimodal - expected if most CpG methylation states
|
|
|
- are homogeneous among cell populations, either all methylated or all unmethylat
|
|
|
-ed.
|
|
|
+.
|
|
|
+ As expected, the weights exactly counteract the trend in the data, resulting
|
|
|
+ in a nearly flat trend centered vertically at 1 (i.e.
|
|
|
+ 0 on the log scale).
|
|
|
+ This shows that the observations with extreme M-values have been appropriately
|
|
|
+ down-weighted to account for the fact that the noise in those observations
|
|
|
+ has been amplified by the non-linear M-value transformation.
|
|
|
+ In turn, this gives relatively more weight to observervations in the middle
|
|
|
+ region, which are more likely to correspond to probes measuring interesting
|
|
|
+ biology (not constitutively methylated or unmethylated).
|
|
|
\end_layout
|
|
|
|
|
|
\begin_layout Standard
|
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|
\begin_inset Float table
|
|
|
wide false
|
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|
sideways false
|
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|
-status open
|
|
|
+status collapsed
|
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|
\begin_layout Plain Layout
|
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|
\align center
|
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|
\begin_inset Tabular
|
|
|
-<lyxtabular version="3" rows="5" columns="2">
|
|
|
+<lyxtabular version="3" rows="5" columns="3">
|
|
|
<features tabularvalignment="middle">
|
|
|
<column alignment="center" valignment="top">
|
|
|
<column alignment="center" valignment="top">
|
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|
+<column alignment="center" valignment="top">
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|
<row>
|
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|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
\begin_inset Text
|
|
@@ -3338,6 +3747,15 @@ status open
|
|
|
Covariate
|
|
|
\end_layout
|
|
|
|
|
|
+\end_inset
|
|
|
+</cell>
|
|
|
+<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
+\begin_inset Text
|
|
|
+
|
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|
+\begin_layout Plain Layout
|
|
|
+Test used
|
|
|
+\end_layout
|
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|
+
|
|
|
\end_inset
|
|
|
</cell>
|
|
|
<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
|
|
@@ -3358,6 +3776,15 @@ p-value
|
|
|
Transplant Status
|
|
|
\end_layout
|
|
|
|
|
|
+\end_inset
|
|
|
+</cell>
|
|
|
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
+\begin_inset Text
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
|
|
+F-test
|
|
|
+\end_layout
|
|
|
+
|
|
|
\end_inset
|
|
|
</cell>
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
@@ -3378,6 +3805,15 @@ Transplant Status
|
|
|
Diabetes Diagnosis
|
|
|
\end_layout
|
|
|
|
|
|
+\end_inset
|
|
|
+</cell>
|
|
|
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
+\begin_inset Text
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
|
|
+t-test
|
|
|
+\end_layout
|
|
|
+
|
|
|
\end_inset
|
|
|
</cell>
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
@@ -3398,6 +3834,15 @@ Diabetes Diagnosis
|
|
|
Sex
|
|
|
\end_layout
|
|
|
|
|
|
+\end_inset
|
|
|
+</cell>
|
|
|
+<cell alignment="center" valignment="top" topline="true" leftline="true" usebox="none">
|
|
|
+\begin_inset Text
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
|
|
+t-test
|
|
|
+\end_layout
|
|
|
+
|
|
|
\end_inset
|
|
|
</cell>
|
|
|
<cell alignment="center" valignment="top" topline="true" leftline="true" rightline="true" usebox="none">
|
|
@@ -3418,6 +3863,15 @@ Sex
|
|
|
Age
|
|
|
\end_layout
|
|
|
|
|
|
+\end_inset
|
|
|
+</cell>
|
|
|
+<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" usebox="none">
|
|
|
+\begin_inset Text
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
|
|
+linear regression
|
|
|
+\end_layout
|
|
|
+
|
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\end_inset
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</cell>
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<cell alignment="center" valignment="top" topline="true" bottomline="true" leftline="true" rightline="true" usebox="none">
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@@ -3441,22 +3895,27 @@ Age
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\begin_inset Caption Standard
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\begin_layout Plain Layout
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+
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+\series bold
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\begin_inset CommandInset label
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LatexCommand label
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name "tab:weight-covariate-tests"
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\end_inset
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-Association of sample weights with clinical covariates.
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+Association of sample weights with clinical covariates in methylation array
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+ data.
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+
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+\series default
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+Computed sample quality log weights were tested for significant association
|
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+ with each of the variables in the model (1st column).
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+ An appropriate test was selected for each variable (2nd column).
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+ P-values for significant association are shown in the 3rd column.
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\end_layout
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\end_inset
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-\end_layout
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-
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-\begin_layout Plain Layout
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-
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\end_layout
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\end_inset
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@@ -3469,7 +3928,8 @@ Association of sample weights with clinical covariates.
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status open
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\begin_layout Plain Layout
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-Redo the sample weight boxplot with notches and without fill colors
|
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+Redo the sample weight boxplot with notches and without fill colors (and
|
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+ update the legend)
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\end_layout
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\end_inset
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@@ -3481,11 +3941,11 @@ Redo the sample weight boxplot with notches and without fill colors
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\begin_inset Float figure
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\begin_inset Graphics
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- filename graphics/methylvoom/unadj.dupcor.sva.voomaw/sample-weights-PAGE3.pdf
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+ filename graphics/methylvoom/unadj.dupcor.sva.voomaw/sample-weights-PAGE3-CROP.pdf
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\end_inset
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@@ -3505,6 +3965,10 @@ name "fig:diabetes-sample-weights"
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\series bold
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Boxplot of sample quality weights grouped by diabetes diagnosis.
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+
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+\series default
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+Sample were grouped based on diabetes diagnosis, and the distribution of
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+ sample quality weights for each diagnosis was plotted.
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\end_layout
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\end_inset
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@@ -3521,21 +3985,64 @@ Boxplot of sample quality weights grouped by diabetes diagnosis.
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\end_layout
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-\begin_layout Itemize
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-Based on estimated sample weights, T2D samples are significantly more variable
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- than T1D samples (t-test p = 1.06e-3)
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-\end_layout
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+\begin_layout Standard
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+To determine whether any of the known experimental factors had an impact
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+ on data quality, the sample quality weights estimated from the data were
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+ tested for association with each of the experimental factors (Table
|
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+\begin_inset CommandInset ref
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+LatexCommand ref
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+reference "tab:weight-covariate-tests"
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+plural "false"
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+caps "false"
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+noprefix "false"
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-\begin_layout Itemize
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-Should not affect further analysis
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+\end_inset
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+
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+).
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+ Diabetes diagnosis was found to have a potentially significant association
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+ with the sample weights, with a t-test p-value of
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+\begin_inset Formula $1.06\times10^{-3}$
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+\end_inset
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+
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+.
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+ Figure
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+\begin_inset CommandInset ref
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+LatexCommand ref
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+reference "fig:diabetes-sample-weights"
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+plural "false"
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+caps "false"
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+noprefix "false"
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+
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+\end_inset
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+
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+ shows the distribution of sample weights grouped by diabetes diagnosis.
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+ The samples from patients with Type 2 diabetes were assigned significantly
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+ lower weights than those from patients with Type 1 diabetes.
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+ This indicates that the type 2 diabetes samples had an overall higher variance
|
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+ on average across all probes.
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+
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\end_layout
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\begin_layout Standard
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\begin_inset Float table
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wide false
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sideways false
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+status collapsed
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+
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+\begin_layout Plain Layout
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+\align center
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+\begin_inset Flex TODO Note (inline)
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status open
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+\begin_layout Plain Layout
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+Consider transposing this table and the next one
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+\end_layout
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+
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+\end_inset
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+
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+
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+\end_layout
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+
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\begin_layout Plain Layout
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\align center
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\begin_inset Tabular
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@@ -3755,11 +4262,21 @@ name "tab:methyl-num-signif"
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\series bold
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Number of probes significant at 10% FDR for each contrast in each analysis.
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-\end_layout
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+
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+\series default
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+For each of the analyses in Table
|
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+\begin_inset CommandInset ref
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+LatexCommand ref
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+reference "tab:Summary-of-meth-analysis"
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+plural "false"
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+caps "false"
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+noprefix "false"
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\end_inset
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-
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+, the table shows the number of probes called significantly differentially
|
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+ methylated at a threshold of 10% FDR for each comparison between TX and
|
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+ the other 3 transplant statuses.
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\end_layout
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\end_inset
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@@ -3767,14 +4284,6 @@ Number of probes significant at 10% FDR for each contrast in each analysis.
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\end_layout
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-\begin_layout Standard
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-\begin_inset Flex TODO Note (inline)
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-status open
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-
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-\begin_layout Plain Layout
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|
-Cite the pi0 estimation method from propTrueNull
|
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-\end_layout
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-
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\end_inset
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@@ -3784,7 +4293,7 @@ Cite the pi0 estimation method from propTrueNull
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\begin_inset Float table
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wide false
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sideways false
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-status open
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+status collapsed
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\begin_layout Plain Layout
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\align center
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|
@@ -4005,6 +4514,20 @@ name "tab:methyl-est-nonnull"
|
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|
\series bold
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|
Estimated number of non-null tests for each contrast in each analysis.
|
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+
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|
+\series default
|
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|
+For each of the analyses in Table
|
|
|
+\begin_inset CommandInset ref
|
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|
+LatexCommand ref
|
|
|
+reference "tab:Summary-of-meth-analysis"
|
|
|
+plural "false"
|
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|
+caps "false"
|
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|
+noprefix "false"
|
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+
|
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|
+\end_inset
|
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+
|
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|
+, the table shows the number of probes estimated to be differentially methylated
|
|
|
+ between TX and the other 3 transplant statuses.
|
|
|
\end_layout
|
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|
\end_inset
|
|
@@ -4018,11 +4541,18 @@ Estimated number of non-null tests for each contrast in each analysis.
|
|
|
\end_layout
|
|
|
|
|
|
\begin_layout Standard
|
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|
+\begin_inset Float figure
|
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|
+wide false
|
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|
+sideways false
|
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|
+status collapsed
|
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+
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|
+\begin_layout Plain Layout
|
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|
\begin_inset Flex TODO Note (inline)
|
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|
status open
|
|
|
|
|
|
\begin_layout Plain Layout
|
|
|
-Re-generate p-value histograms for all relevant contrasts in a single figure.
|
|
|
+Re-generate p-value histograms for all relevant contrasts in a single page,
|
|
|
+ then write an appropriate legend.
|
|
|
\end_layout
|
|
|
|
|
|
\end_inset
|
|
@@ -4030,9 +4560,44 @@ Re-generate p-value histograms for all relevant contrasts in a single figure.
|
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|
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Itemize
|
|
|
-Better variance properties in analyses B and C give more significant probes
|
|
|
- (10% FDR)
|
|
|
+\begin_layout Plain Layout
|
|
|
+\align center
|
|
|
+
|
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|
+\series bold
|
|
|
+[Figure goes here]
|
|
|
+\end_layout
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
|
|
+\begin_inset Caption Standard
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
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|
+
|
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|
+\series bold
|
|
|
+\begin_inset CommandInset label
|
|
|
+LatexCommand label
|
|
|
+name "fig:meth-p-value-histograms"
|
|
|
+
|
|
|
+\end_inset
|
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|
+
|
|
|
+Probe p-value histograms for each contrast in each analysis.
|
|
|
+\end_layout
|
|
|
+
|
|
|
+\end_inset
|
|
|
+
|
|
|
+
|
|
|
+\end_layout
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
|
|
+
|
|
|
+\end_layout
|
|
|
+
|
|
|
+\end_inset
|
|
|
+
|
|
|
+
|
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|
+\end_layout
|
|
|
+
|
|
|
+\begin_layout Standard
|
|
|
+Table
|
|
|
\begin_inset CommandInset ref
|
|
|
LatexCommand ref
|
|
|
reference "tab:methyl-num-signif"
|
|
@@ -4042,7 +4607,57 @@ noprefix "false"
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
-, more probes estimated to be differentially methylated
|
|
|
+ shows the number of significantly differentially methylated probes reported
|
|
|
+ by each analysis for each comparison of interest at an FDR of 10%.
|
|
|
+ As expected, the more elaborate analyses, B and C, report more significant
|
|
|
+ probes than the more basic analysis A, consistent with the conclusions
|
|
|
+ above that the data contain hidden systematic variations that must be modeled.
|
|
|
+ Table
|
|
|
+\begin_inset CommandInset ref
|
|
|
+LatexCommand ref
|
|
|
+reference "tab:methyl-est-nonnull"
|
|
|
+plural "false"
|
|
|
+caps "false"
|
|
|
+noprefix "false"
|
|
|
+
|
|
|
+\end_inset
|
|
|
+
|
|
|
+ shows the estimated number differentially methylated probes for each test
|
|
|
+ from each analysis.
|
|
|
+ This was computed by estimating the proportion of null hypotheses that
|
|
|
+ were true using the method of
|
|
|
+\begin_inset CommandInset citation
|
|
|
+LatexCommand cite
|
|
|
+key "Phipson2013"
|
|
|
+literal "false"
|
|
|
+
|
|
|
+\end_inset
|
|
|
+
|
|
|
+ and subtracting that fraction from the total number of probes, yielding
|
|
|
+ an estimate of the number of null hypotheses that are false based on the
|
|
|
+ distribution of p-values across the entire dataset.
|
|
|
+ Note that this does not identify which null hypotheses should be rejected
|
|
|
+ (i.e.
|
|
|
+ which probes are significant); it only estimates the true number of such
|
|
|
+ probes.
|
|
|
+ Once again, analyses B and C result it much larger estimates for the number
|
|
|
+ of differentially methylated probes.
|
|
|
+ In this case, analysis C, the only analysis that includes voom, estimates
|
|
|
+ the largest number of differentially methylated probes for all 3 contrasts.
|
|
|
+ If the assumptions of all the methods employed hold, then this represents
|
|
|
+ a gain in statistical power over the simpler analysis A.
|
|
|
+ Figure
|
|
|
+\begin_inset CommandInset ref
|
|
|
+LatexCommand ref
|
|
|
+reference "fig:meth-p-value-histograms"
|
|
|
+plural "false"
|
|
|
+caps "false"
|
|
|
+noprefix "false"
|
|
|
+
|
|
|
+\end_inset
|
|
|
+
|
|
|
+ shows the p-value distributions for each test, from which the numbers in
|
|
|
+ Table
|
|
|
\begin_inset CommandInset ref
|
|
|
LatexCommand ref
|
|
|
reference "tab:methyl-est-nonnull"
|
|
@@ -4052,7 +4667,44 @@ noprefix "false"
|
|
|
|
|
|
\end_inset
|
|
|
|
|
|
-, and better looking p-value distributions [histogram figures].
|
|
|
+ were generated.
|
|
|
+ The distributions for analysis A all have a dip in density near zero, which
|
|
|
+ is a strong sign of a poor model fit.
|
|
|
+ The histograms for analyses B and C are more well-behaved, with a uniform
|
|
|
+ component stretching all the way from 0 to 1 representing the probes for
|
|
|
+ which the null hypotheses is true (no differential methylation), and a
|
|
|
+ zero-biased component representing the probes for which the null hypothesis
|
|
|
+ is false (differentially methylated).
|
|
|
+ These histograms do not indicate any major issues with the model fit.
|
|
|
+\end_layout
|
|
|
+
|
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|
+\begin_layout Standard
|
|
|
+\begin_inset Flex TODO Note (inline)
|
|
|
+status open
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
|
|
+Maybe include the PCA plots before/after SVA effect subtraction?
|
|
|
+\end_layout
|
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+
|
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|
+\end_inset
|
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+
|
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+
|
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|
+\end_layout
|
|
|
+
|
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|
+\begin_layout Standard
|
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|
+\begin_inset ERT
|
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|
+status collapsed
|
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|
+
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|
+\begin_layout Plain Layout
|
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+
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+
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+\backslash
|
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|
+FloatBarrier
|
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|
+\end_layout
|
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+
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|
+\end_inset
|
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+
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+
|
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|
\end_layout
|
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|
|
|
|
\begin_layout Section
|
|
@@ -4166,8 +4818,25 @@ literal "false"
|
|
|
Because these vectors were each generated using training samples from a
|
|
|
single tissue, they are not suitable for general use, unlike the vectors
|
|
|
provided with fRMA itself.
|
|
|
- They are purpose-build for normalizing a specific type of sample on a specific
|
|
|
+ They are purpose-built for normalizing a specific type of sample on a specific
|
|
|
platform.
|
|
|
+ This is a mostly acceptable limitation in the context of developing a machine
|
|
|
+ learning classifier for diagnosing a disease based on samples of a specific
|
|
|
+ tissue.
|
|
|
+\end_layout
|
|
|
+
|
|
|
+\begin_layout Standard
|
|
|
+\begin_inset Flex TODO Note (inline)
|
|
|
+status open
|
|
|
+
|
|
|
+\begin_layout Plain Layout
|
|
|
+How to bring up that these custom vectors were used in another project by
|
|
|
+ someone else that was never published?
|
|
|
+\end_layout
|
|
|
+
|
|
|
+\end_inset
|
|
|
+
|
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|
+
|
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|
\end_layout
|
|
|
|
|
|
\begin_layout Subsection
|
|
@@ -4389,7 +5058,7 @@ literal "false"
|
|
|
Methods
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Subsection*
|
|
|
+\begin_layout Subsection
|
|
|
Sample collection
|
|
|
\end_layout
|
|
|
|
|
@@ -4407,7 +5076,7 @@ All research reported here was done under IACUC-approved protocols at the
|
|
|
additive.
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Subsection*
|
|
|
+\begin_layout Subsection
|
|
|
Globin Blocking
|
|
|
\end_layout
|
|
|
|
|
@@ -4436,7 +5105,7 @@ HBB site 1: AAUGAAAAUAAAUGUUUUUUAUUAG-C3spacer
|
|
|
HBB site 2: CUCAAGGCCCUUCAUAAUAUCCC-C3spacer
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Subsection*
|
|
|
+\begin_layout Subsection
|
|
|
RNA-seq Library Preparation
|
|
|
\end_layout
|
|
|
|
|
@@ -4513,7 +5182,7 @@ t with 75 base read lengths.
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Subsection*
|
|
|
+\begin_layout Subsection
|
|
|
Read alignment and counting
|
|
|
\end_layout
|
|
|
|
|
@@ -4569,7 +5238,7 @@ e” (LOC102136192 and LOC102136846).
|
|
|
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Subsection*
|
|
|
+\begin_layout Subsection
|
|
|
Normalization and Exploratory Data Analysis
|
|
|
\end_layout
|
|
|
|
|
@@ -4611,7 +5280,7 @@ literal "false"
|
|
|
.
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Subsection*
|
|
|
+\begin_layout Subsection
|
|
|
Differential Expression Analysis
|
|
|
\end_layout
|
|
|
|
|
@@ -4643,7 +5312,7 @@ literal "false"
|
|
|
variation using an additive model with coefficients for transplant and
|
|
|
animal ID.
|
|
|
In all analyses, p-values were adjusted using the Benjamini-Hochberg procedure
|
|
|
- for FDR correction
|
|
|
+ for FDR control
|
|
|
\begin_inset CommandInset citation
|
|
|
LatexCommand cite
|
|
|
key "Benjamini1995"
|
|
@@ -4675,7 +5344,7 @@ Blood RNA-seq time course after transplants with/without MSC infusion
|
|
|
Results
|
|
|
\end_layout
|
|
|
|
|
|
-\begin_layout Subsection*
|
|
|
+\begin_layout Subsection
|
|
|
Globin blocking yields a larger and more consistent fraction of useful reads
|
|
|
\end_layout
|
|
|
|
|
@@ -5456,7 +6125,7 @@ noprefix "false"
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fraction.
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\end_layout
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-\begin_layout Subsection*
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+\begin_layout Subsection
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Globin blocking lowers the noise floor and allows detection of about 2000
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more genes
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\end_layout
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@@ -5684,7 +6353,7 @@ noprefix "false"
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).
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\end_layout
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-\begin_layout Subsection*
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+\begin_layout Subsection
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Globin blocking does not add significant additional noise or decrease sample
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quality
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\end_layout
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@@ -5948,7 +6617,7 @@ literal "false"
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the negligible increase in BCV.
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\end_layout
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-\begin_layout Subsection*
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+\begin_layout Subsection
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More differentially expressed genes are detected with globin blocking
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\end_layout
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