Genetic effects that are common and large are unusual for human diseases and traits studied using GWAS (Figure 1b). They are occasionally found for less complex conditions that can be assessed with exceptional precision (e.g., infectious diseases, rare adverse drug reactions, and eye diseases). To our knowledge, the largest common genetic variant associations observed to date in psychiatry are for alcoholism in people of East Asian ancestry (GRR ~6.2) and clozapine-induced agranulocytosis (GRR ~5.3) (20, 21).
