In a recently published meta-analysis of randomized controlled trials, we demonstrated that pharmacogenomic testing which include CYP2D6 and CYP2C19 genetic variants is a useful tool to increase effectiveness of antidepressant treatment in major depressive disorders with odds for improvement, response, and remission in the range of 1.46–1.85 compared to treatment as usual [7]. The gene discussed is CYP2C19; the disease is major depressive disorder.