LAUSR

Description Mating patterns across two traits can inflate estimates of genetic overlap Genome-wide association studies (GWASs) identify genetic variants associated with a trait. Most traits are associated with thousands of variants, and many variants are pleiotropic, meaning they are associated with multiple traits. Pervasive pleiotropy makes it impractical to assess genetic overlap between two traits by tallying the shared variants. For example, traits such as major depression and anxiety are likely associated with a shared set of thousands of variants. Genetic correlation (rg) estimated from GWASs of a pair of traits is typically interpreted as an overall measure of genetic overlap, providing a useful metric for quantifying shared biology between traits. On page 754 of this issue, Border et al. (1) report simulation-based and empirical findings that challenge this interpretation.