Highly DE genes but small count difference within conditions
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@01d91c6f
Last seen 14 minutes ago
Italy

Hello! I am looking for DE genes comparing condition1 vs control. I have 3 biological replicates per each case, so 6 in total. I am using this design:

design=~ sex + condition

and I am filtering low expressed genes in this way:

smallestGroupSize <- 3 
keep <- rowSums(counts(dds0) >= 10) >= smallestGroupSize

Then I get my DE that looks like this, with lfc=+/-1.5 and padj<0.005 volcano_plot

But when i then look at raw counts and tpm of Slfn5 looks like this: enter image description here enter image description here

Why do I get this high padjusted value for this gene?

RNASeq DESeq2 RNASeqData • 49 views
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@mikelove
Last seen 1 hour ago
United States

Could be due to controlling for sex. You have only three samples?

Dropping sex would likely remove such genes as marginally you don't see a trend.

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Hello Michael, thanks for your answer. Yes, I have only 3 samples :(. Dropping sex would remove those genes but at the same time does not include other DE genes. For example:tpm_Eif3j1 is not included. This is also valid the other way around with design=~genotype. I was wondering if could be a possibility to use a more stringent filtering based on condition and variance for the multivariate model, what do you think?

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TPM is not a robust scaling method and can be influenced by changes in global distribution.

What do you get with an MA plot. Can you highlight these genes in an MA plot?

Also how about a box plot of log (raw) counts eg

boxplot(log10(counts(dds)+1))

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These are the MA plot for design=~sex+genotype and boxplots with boxplot(log10(counts(dds)+1)) MA plot sample_boxplot box

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