Summary statistics from both SRE scores in COGA-AA and COGA-EA were used to derive PRS using PRSice-2 (Euesden et al., 2015). Four test datasets from the database of Genotypes and Phenotypes (dbGaP) were included: 1) AA subsample (SAGE-AA) in the Study of Addiction: Genetics and Environment (SAGE, phs000092.v1.p1); 2) AA subsample (Yale-Penn-AA) in Alcohol Dependence GWAS in European and African Americans (phs000425.v1.p1); 3) EA subsample in SAGE (SAGE-EA); and 4) EA subsample (OZALC-EA) in The Australian Twin-family Study of Alcohol Use Disorder (OZALC, phs000181.v1.p1). Overlapping COGA individuals were excluded from these independent datasets. PRSice-2 requires the analysis of unrelated samples; therefore, in datasets with related individuals, one individual was randomly selected from each family. Summary of each test dataset is shown in supplemental material. Any variant that was within 500 kb from the index variant and had r2 >=0.25 with the index variant was clumped using PRSice-2. PRS was calculated based on effect size (Euesden et al., 2015). To reduce the burden of multiple testing, only variants that had p values <0.05 were included. For SAGE, sex and the same
