Heritability was estimated for DSM-IV AD, each of the DSM-IV criteria, and the three traits defined by the probability of belonging to each of latent class (Table 3), after covarying for effects of sex and birth cohort on the phenotype. Heritability for AD was estimated to be 61%. Estimates of heritability for the individual criteria ranged from 59% (drinking more than intended) to 29% (tolerance). Heritability of membership in the low and high-risk classes was 0.52 and 0.53. Due to the redundancy of including all three probabilities and the low heritability of the moderate risk class (0.17), this phenotype was not included in the GWAS.
