Hi all, I am quite new around here, so if it was asked sorry for creating a duplicated post, but I could not find it. I have TCGA data downloaded and trying to analyze differentially expressed genes by using edgeR.
in BRCA, two of genes have p-values and FDR zero (I don't know if it is an underflow or literally zero) and fold changes around -3,5 and -2,4. I don't know how to interpret these extremely low p-values. Are they because of a biological variation or a statistical error? Maybe I should have made some kind of normalization? Additionally, my p-values of other genes are extremely low, too (around e-305) and for other cancers I found p-values around e-60. So maybe, I am missing something.
edit: I am working with patient tumor/normal tissue pairs.