Analyses in both populations were adjusted for ancestry PCs, sex, and age. To characterize the underlying genetic architecture of the samples using PCs, we first applied two filters to all markers: linkage disequilibrium pruning (using PLINK (20) option –indep, with threshold > 1%) and minor allele frequency (MAF) screening (MAF < 1%). We conducted PC analysis separately within the EAs and AAs using FlashPCA (21). The first 10 PCs were used in all subsequent analyses to correct for residual population stratification.
