Shared heritability among psychiatric disorders and traits

Accumulating evidence shows that psychiatric disorders are highly polygenic and that there is a large degree of genetic overlap among these disorders and related traits. In this chapter, we provide an overview of the concepts of heritability and overlapping genetic architecture, as well as a comprehensive breakdown of the available methods and approaches to investigate and analyze shared heritability due to common genetic variation. Also provided are details of known rare variant overlap for psychiatric disorders. Finally, we highlight the implications of this extensive shared heritability in relation to the goal of precision psychiatry, including diagnostic accuracy and prediction algorithms.