As of October 2011, there were 127 unique trait-SNP associations reported in the National Human Genome Research Institute’s (NHGRI) GWAS catalog for electrocardiographic (ECG) traits (http://www.genome.gov/gwastudies/). Most of these studies were limited to European (118 associations) or Asian (9 associations)-descent populations, and it is unclear if these GWAS-identified variants generalize across populations, particularly the extent to which these associations generalize to African Americans. There is considerable variability in ECG traits across populations. African Americans have a shorter QRS duration, QTc interval, and a longer PR interval compared to Europeans (Ramirez et al. 2011). From a genetic standpoint, there are also significant differences in allele frequencies and linkage disequilibrium patterns between Africans and Europeans. For example, rs7626962 (S1103Y) in SCN5A is rare in European and Asian-descent populations but is common in African Americans and has been linked to arrhythmia susceptibility (Jeff et al. 2011; Splawski et al. 2002). Expanding genetic association studies to diverse populations has been of recent interest to many investigators in the field. To date there has been one GWAS published for ECG traits in African Americans on
