In the second study, GWAS regions identified for the QT interval in European and Asian populations were further fine-mapped in >8,000 African Americans (Avery et al. 2012). Approximately 40% of the associations reported in European or Asian populations generalized in the African American study population, which is consistent with this present study’s generalization results, despite differences in sample size. Three novel associations with QT interval specific to African Americans were also reported; of these, two of the reported SNPs were not on the Illumina 1M BeadChip used for this present study, and one SNP (rs12061601) did not replicate in our African American study population (Supplementary Table 5). The fine-mapping effort also highlighted differences in the index SNP associated with QT interval between African Americans and Europeans. We compared the index SNPs reported in African Americans from the fine-mapping study to our study population (Supplementary Table 5). Of the fifteen index SNPs reported, only six SNPs were directly genotyped in our study of which only two, rs1805120 and rs735951, trended towards significance (Supplementary Table 5).
