Pharmacogenetics, race, and psychiatry: prospects and challenges

Although the field of pharmacogenetics has existed for nearly 50 years, it has begun to enter mainstream clinical practice only recently. Researchers and clinicians have now demonstrated that a wide assortment of genetic variants influence how individuals respond to medications. Many of these variants are relevant for psychiatry, affecting how patients respond to most antidepressants, antipsychotics, anxiolytics, and mood stabilizers. Enthusiasts hope that pharmacogenetics will soon usher in a new era of individualized medicine. However, determining the practical relevance of pharmacogenetic variants remains difficult, in part because of problems with study design and replication, and in part because a host of nongenetic factors (including age, diet, environmental exposures, and comorbid diseases) also influence how individuals respond to medications. Since individualized pharmacogenetic assessment remains difficult, some researchers have argued that race provides a convenient proxy for individual genetic variation, and that clinicians should choose medications and doses differently for different races. This approach remains extremely controversial because of the complexity of the genetic structure of the human population, the complexity of gene-environment interactions, and the complexity of the meanings of race in the United States.