We assessed the clinical value of pharmacogenomic testing examining the differences in psychometrics mean scores at baseline between genotyped and non-genotyped patients; and assessed the relationships between PK (CYP2D6 and CYP2C19) or PD (SLC6A4) genetic variations, and MDD/BP severity scales in pharmacogenomically-tested vs. not tested patients. This evidence concerns the gene CYP2D6 and major depressive disorder.