We calculated the coded allele frequencies for previously identified SNPs (from European descent populations) in African Americans (Supplementary Table 3). To measure population differences, we calculated FST for all SNPs previously identified by GWAS in European descent populations that report sample sizes and minor allele frequencies (85 SNPs). There were 20 SNPs with an FST value >0.15 (ranging from 0.15 to 0.85), which is indicative of significant population differentiation at these loci. We observed the largest FST value (F= 0.85) for rs789852 located in the intron region of the TMEMFF gene located on chromosome 3. This SNP was previously associated with QT interval in Europeans (β= 0.25, p=7.0 × 10−7 ) (Marroni et al. 2009). This association did not generalize in African Americans and trended in the opposite direction compared to Europeans (β = −0.95, p =0.60).
