Unsuccessful DE analysis using limma

This might be a bit long, please bare with me. I’m conducting a differential expression analysis using limma – voom. My comparison is regarding response vs non-response to a cancer drug. However, I’m not getting any DE genes, absolute zeros. Someone here once recommended not to use contrast matrix for such a simple task, so I did that but then I get almost all 18 thousand genes as DE, so that’s not good either. I don’t know what is the problem here. The counts matrix and metadata matrix have the same samples with the exact same order. I filtered my counts matrix from noise genes earlier. I did everything according to this guide: bioconductor.org/packages/release/workflows/vignettes/RNAseq123/inst/doc/limmaWorkflow.html

<h5>Note: This problem is not only in this dataset, this is just one of many. So the problem is probably in my code.</h5>

Let me show you the code and the results I get:

Code:

d0 = DGEList(counts)
group = metadata$Response
d0$samples$group = group
geneid = rownames(d0)
d0$genes = geneid
d0 =  calcNormFactors(d0, method = 'TMM')
dim(d0)

## Design
design = model.matrix(~ 0 + Response, metadata) %>% as.data.frame()
colnames(design)[c(1,2)] = c('NoResponse','Response')

## Contrast
contrast = makeContrasts(NoResp_VS_Resp = NoResponse - Response, levels = colnames(design))

Voom <- voom(d0, design, plot = TRUE)
vfit <- lmFit(Voom, design = design) 
vfit  <- contrasts.fit(vfit , contrasts = contrast) 
efit <- eBayes(vfit) 
plotSA(efit, main = 'final model: Mean-Variance trend')

summary(decideTests(efit))

deg <- topTable(efit, 
                coef="NoResp_VS_Resp",
                 p.value = 0.05,
                 adjust.method = 'fdr',
                 number = Inf)

Now you might ask how does the Voom and the eBayes plots look like, here they are:

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And here is the summary(decideTests(efit)) results when using contrast matrix:

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And this is without contrast matrix: ( Almost 17 thousand significant genes, out of 18 thousand)

enter image description here

Can anyone help me figure out what is the problem ? If any additional info is needed I’ll add it!

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