Genetics of Bipolar Disorder

Abstract

An individual’s genetic makeup has the power to inform medical practice and shape disease prevention, diagnosis, and treatment to improve lifelong outcomes. Genetics has integrated into some aspects of general medicine; however, there has been less success in incorporating genetics into psychiatry. This chapter discusses the genetics of bipolar disorder. As revealed from family, twin, and adoption studies, bipolar disorder is highly heritable, with estimates suggesting the disorder coincides with the highest heritability compared with other psychiatric disorders. While association studies have identified genes of interest that may contribute to risk for the disorder, these studies have been difficult to replicate, and genes identified have shown small effect sizes on their own. More recent approaches to studying polygenic risk and epigenetics modifications of the genome are starting to be applied to bipolar disorder. Early findings utilizing these approaches are discussed. Additionally, this chapter discusses emerging work suggesting genetic associations that may cross diagnostic boundaries in psychiatry and genetic endophenotypes that may one day be incorporated into clinical practice for improving prediction, diagnosis, and treatment of bipolar disorder. While more work is needed to understand the genetics of bipolar disorder and ways to integrate genetics into clinical practice, there is hope on the horizon, and familial information can already guide clinical practice.