Large-scale genome-wide studies of complex traits illustrate several key propositions. First, bigger is better. Large genome-wide association studies (GWAS) can uncover novel biology. Second, similarly to other complex traits5, genetic findings from European populations (EUR; e.g., European-Americans) greatly exceed those from other populations (e.g., African-Americans (AAs)). Third, candidate genes [G] selected based on known biology, which have a dismal record in the field as a whole6, 7, have been successfully replicated by large-scale SUD GWAS in a few instances.
