The implications of genetic studies of major mood disorders for clinical practice

Background: This article is a selective review and synthesis of relevant research findings from genetic studies of major mood disorders and the application of these to clinical practice. Method: The article discusses the application of genetic research findings in major mood disorders, including epidemiologic and family study risk estimates, risk modifiers, and the concepts of etiologic and phenotypic heterogeneity, to 3 clinical domains: risk counseling, diagnosis, and treatment prediction. Results: Epidemiologic and family studies have provided general risk estimates useful in counseling mood-disordered patients and their relatives. A complete and accurate family pedigree provides more individualized risk estimates for specific cases and is useful in identifying the phenotypic spectrum of the disorder being transmitted in the family. Both proband course parameters and familial loading for psychiatric illnesses may be relevant for the prediction of treatment response. However, the hypothesis of inherited pharmacologic selectivity remains to be proven. Conclusion: Genetic studies of mood disorders have not yet provided conclusive evidence of specific susceptibility genes or their pattern of inheritance. However, they have generated information that is useful to clinical practice.