[BioC] number of genes for DESeq analysis

[vladimir mashanov]

Dear All,

I have carried out an RNAseq experiment with 4 conditions, 2
biological replicates of each. In the moment, I am interested in how
my conditions differ in terms of expression of a subset of 36 genes.
The idea is to count only the reads, which correspond to those 36
genes and use this piece of data for the analysis of their
differential expression across the conditions. Will this approach be
valid? What is the minimum number of genes required by the statistical
model implemented in DESeq? I apologize if the question are too naive.

Thank you

Vladimir.