CYP2D6 and major depressive disorder: 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.