Details regarding the QC criteria were reported previously17. Briefly, after initial sample and variant QC, population outlier samples were excluded, and each retained individual was assigned to a specific ancestry on the basis of the principal components derived from genome-wide data. The 1000 Genomes Project Phase 3 reference panel19 was used as a reference for the ancestry assignment. Based on genetic information, we identified 9,591 and 31,585 individuals of African and European descent, respectively. Other ancestry groups were not investigated due to the limited number of informative subjects. The final QC criteria included variant filters for call rate, heterozygosity, and departure from Hardy–Weinberg equilibrium expectations (HWE), performed within each ancestry group in each cohort stratified by genotyping array. We also used sample QC filters for cryptic relatedness and for departures from reported pedigree structures. Imputation was performed using SHAPEIT220 and IMPUTE221, and the 1000 Genomes Project Phase 3 reference panel, which includes five continental groups19. High-quality imputed SNPs were retained for the association analysis, filtering for imputation INFO score > 0.8 and minor allele frequency (MAF) > 0.01 before analysis.
