One of the most rapidly emerging areas of neuroscience research is the study of genetic approaches to complex psychiatric disorders. The author discusses potential benefits and pitfalls of candidate gene association studies. Association studies search for correlations in the population between a DNA marker and a disorder. The so-called candidate gene approach is frequently used in association studies. Candidate gene studies are usually based on hypotheses about relationships between specific known loci and particular phenotypes. The aim of molecular genetic studies of behavioral disorders includes the development of predictive and diagnostic testing for psychiatric disorders that can help to establish the accurate diagnosis and the identification of target for therapeutic drugs. To date, case-control association studies investigating polymorphisms of candidate genes in psychiatric disorders have produced a lot of positive and negative findings with few consistent replications. The false positive and false negative findings in candidate gene association studies are due to population stratification, heterogeneity of psychiatric disorders, multiple tests, low prior odds of association, and small sample size. A researcher planning a genetic association study for a psychiatric disorder needs to have the following: 1) suitable phenotypes; 2) a good rationale for studying not only the gene in question, but the specific polymorphism; 3) enough subjects and control for meaningful analyses; and 4) use of ethnically homogenous case-control data sets or family based association designs.
Sher, Leo M.D.
"Current methodological Issues in Candidate Gene Association Studies in Psychiatric Disorders,"
Jefferson Journal of Psychiatry:
1, Article 6.
Available at: http://jdc.jefferson.edu/jeffjpsychiatry/vol17/iss1/6