Phenotypic and genetic analyses showed that AUDIT items were positively correlated with each other, with correlation estimates ranging from moderate to large (Tables S3–4). The one exception to this pattern was item 1 (i.e., frequency of consumption), which was generally less correlated with the other AUDIT items. Moreover, we found that genetic correlations tended to be moderately larger than the phenotypic correlations (mean absolute difference = .198), an effect that was driven by stronger genetic correlations among items 4 through 10 (i.e., the problematic alcohol use phenotypes). Of note, all AUDIT items exhibited significant SNP heritability with the exception of item 6 (Table S5). We suspect this may be attributable to the low rates of endorsement for the item in all three cohorts (Table S2). For this reason, we excluded item 6 from all subsequent analyses, and a factor extension analysis was used to estimate its expected factor loading in the final model.
