I apologize in advance for the level of simplicity of the question but I have been trying to wrap my head around this for a while now and I would like to hear sb's else opinion.
I am checking the expression of four genes in two different tissues (liver and kidney). I am interested in examining the difference in expression (for each gene separately) between the two tissues and report it separately. I am not interested in any comparisons between genes' expression. I am using a single linear mixed model and then using contrasts I am examining the significance of the difference in expression of gene A, of gene B, of gene C and of gene D.
If I do not correct (e.g. Bonferroni) 2/4 contrasts are significant. If I correct then nothing is significant. My question is: why should I correct since I am examining the difference in gene expression, for each gene separately... and therefore I could have 2 genes or 20.000 genes...
any advice is very welcome