UKBiobank43, and DSM-5 Alcohol Use Disorder from the Million Veteran Program in individuals of European ancestry44. For participants of African ancestry, GWAS summary statistics were drawn from the meta-analyzed European ancestry summary statistics in tandem with the African ancestry GWAS summary statistics from analyses of DSM-IV alcohol dependence from the Psychiatric Genomics Consortium (COGA sample removed)42 and the African ancestry GWAS summary statistics from analyses of Alcohol Use Disorder derived from ICD codes obtained from electronic health records from the Million Veteran Program44. This approach was informed by evidence that combining African ancestry specific GWAS summary statistics with GWAS summary statistics available from a larger-scale European ancestry sample improves polygenic prediction in an African-ancestry target sample41. Following the calculation of the posterior effect sizes, additive polygenic scores were calculated for transmitted and nontransmitted alleles for mothers and fathers, separately. SNPs where parental origin was ambiguous (e.g., an offspring C/T SNP for parents who are C/T heterozygotes) were removed from the PRS calculation.
