Pharmacogenomics of treatment response in major depressive disorder

Antidepressants are widely used to treat major depressive disorder. However, many patients have a suboptimal response to specific pharmacotherapy, and thus identification of factors that contribute to treatment response is a high priority. It is increasingly recognized that genetic variation, both pharmacokinetic and pharmacodynamic, can influence antidepressant treatment outcomes. Candidate gene studies have provided insights into antidepressant pharmacogenomics, but also often produced inconsistent findings. Because of inadequate power, genome-wide association studies have identified limited genetic variation that impacts antidepressant response. Ongoing efforts include large collaborative studies to identify additional relevant genetic variation, and application of novel analytical methods to further our understanding of antidepressant pharmacogenomics. Nevertheless, tests that pharmacogenetically guide antidepressant selection have become available in clinical practice, and there is much hope that such tests will be improved over the next decade, and will have an important positive impact on patient outcomes.