For pharmacogenetic analysis, common functional variants in <i>CYP1A2</i>, <i>CYP3A4</i>, <i>CYP2B6</i>, <i>CYP2C19</i>, and <i>CYP2D6</i> were genotyped, and corresponding evidence-based treatment recommendations were prepared.<h4>Results</h4>The patient suffered from lack of efficacy and serious ADR of several medications, resulting in worsening depression and treatment resistance over the course of several months of treatment. Here, CYP2C19 is linked to major depressive disorder.