Genetics of depression: Implications for clinical practice yet?

Objective: The objective of this manuscript is to outline the possibilities of using genetics to guide clinical decision behaviors in the treatment and management of Major Depressive Disorder (MDD). Method: A critical assessment of the state of the science on genetics of MDD and antidepressant response was performed. This review covers the results of traditional genetic approaches when investigating the influence of genes on a phenotypic outcome, and includes family, twin and adoption studies. A more comprehensive assessment of the results of molecular genetic studies of MDD and antidepressant response, including candidate gene, genome-wide association, and gene expression studies are covered. Results: The current state of the science for the role of genetics in guiding clinical behavior is still in development. In spite of all the research completed to date, no genetic variations have conclusively been found to be a predictor of risk or provide confirmation (acts as a biomarker) of MDD diagnosis. Similarly, the studies of the pharmacogenetics of antidepressant response have been unremarkable, and do not help in guiding prescribing decisions for MDD patients at the present time. There is more progress for predicting antidepressant response when considering variations in pharmacokinetic genes, however, these studies still require further development. Conclusions: Currently genetics cannot provide much algorithm-based guidance for treatment or management of MDD. It could still be several years of research before a true genetic biomarker will be available for MDD and antidepressant response. Technological advances in the processing on genetic samples, statistical computing, database management, and increasingly collaborative studies will be required to achieve this end. Until then, the best predictor of what antidepressant will work for each patient, is the one that worked for their immediate relatives clinically.