Pharmacogenomics in Psychiatric Disorders

Significant variabilities exist in psychotropic disposition and response. Numerous polymorphisms in the genes coding for specific cytochrome P-450 metabolizing enzymes and the ABCB1 transporter residing at the blood–brain barrier have been studied for their possible roles in individualized psychotropic drug therapy. Although molecular diagnostics are available for CYP2D6 and CYP2C19 genotyping, current data provide evidence for their use primarily in predicting adverse drug effects and possibly increasing compliance in subsets of populations. The involvement of the serotonergic system, especially the 5-HT2C receptor, provides convincing evidence of a genetic basis in predicting antipsychotic-induced weight gain. On the other hand, prediction of psychotropic drug effects based on polymorphisms in multiple drug targets within the brain is limited by methodological and clinical problems, especially with the candidate gene approach. Nevertheless, the lack of novel new drugs in psychiatry underscores the importance of refining current molecular approaches to provide insights into etiologies of mental disorders and their treatment.