Pharmacogenetics and psychoactive drug therapy: ready for the patient?

Psychiatry is one of the most promising areas for bringing pharmacogenomics to the patient. Psychiatric disorders such as depression and schizophrenia contribute significantly to worldwide morbidity and mortality. Forecasts rank depression second only to ischemic heart disease by 2020. In depression and schizophrenia, 30% to 50% of all patients do not respond sufficiently to the initial treatment regime. Genetic variability has been demonstrated to play an important role in the response to pharmacotherapy. Most data are available with regard to polymorphisms in the genes coding for drug-metabolizing enzymes and recommendations for the choice of personalized dosages based on genotyping results are available. Clinical outcome, in particular adverse effects, has been shown to correlate with the results from genotyping. Incorporating pharmacogenomics into clinical practice has, however, been slow and it is still not clear in which clinical situations genotyping should be performed and what the benefit of such procedures could be beyond therapeutic drug monitoring. Additionally, many studies in psychiatry focus on genetic variation in candidate genes of drug targets. However, despite promising reports, no clear recommendation can be given at present to perform such testing in clinical use.