African 1000 Genomes Project phase 3 data. yielding a sample of 4,737 of European Americans and 1232 African individuals. Due to the sensitivity of the PRS approach to admixture, we took a conservative approach and performed stringent exclusion for ancestral outliers, consistent with the Psychiatric Genomics Consortium’s Ricopili pipeline (13). After selection, a final ancestrally-informative PCA was conducted, and the first 20 PCs were projected from founders to other relatives. Imputation to 1000 Genomes and Haplotype Reference Consortium (HRC) data for Europeans and the Consortium on Asthma among African-ancestry Populations in the Americas (CAAPA) for African Americans was conducted using strictly QCed SNPs. Data were converted to hard-call genotypes using Plink, and only SNPs with imputation r2 scores ≥ 0.3 were used to create polygenic scores.
