Comparing multiple genes expression with z-score

Question

[paulklein05]

Hello everyone,

I would like to compare several genes expression between 2 populations (of cells) as a whole.

I compared each individual genes expression using a log+z-score transformation before applying a statistical test (a one-sided t-test) to look for individual gene downregulation.

Now I would like to compare n genes at the same time between the 2 populations and check if I have a general downregulation or not.

Can I apply the same method ? Or z-scores do not make sense when comparing different genes together ?

Thank you very much for your help !