As previously mentioned, there have been one recent GWAS and one fine-mapping study performed in African Americans for ECG traits (Avery et al. 2012; Smith et al. 2011). The first GWAS in African Americans for PR interval described an association between SCN5A intronic rs3922844 and increased PR interval (Smith et al. 2011). This association was also identified in an independent candidate gene study of SCN5A in African Americans (Jeff et al. 2011). In the present study, rs3922844 was associated with PR interval at p = 0.01 and a consistent direction of effect (β = 3.06) compared with the published reports (Supplementary Table 4). To date rs3922844 has only been identified in African descent populations and thus was not included in this generalization analysis. Although not statistically significant, we observed similar results for the other SNPs published by Smith et al (2011) (Supplementary Table 4). Despite the lack of power, these data collectively suggest and confirm previous reports that SCN5A has pleiotropic effects and is associated with multiple ECG traits in African Americans (Supplementary Table 4) (Jeff et al. 2011).
