a | Comparison of the frequencies of SNPs shared among African–American and European–American populations from the Genaissance panel in which 3,931 genes were resequenced (see online supplementary information S6 (data)). The less frequent allele in the combined population was designated as the minor allele, and the frequency of the minor allele was calculated in each population for the 50,735 SNPs analysed. A linear correlation of the minor allele frequency in European–Americans with the minor allele frequency in African–Americans had an R² (coefficient of determination) of 0.37. Sites where the allele frequency in each population was not significantly different (|Z| <1.65, p >0.05) are shown as black circles. Sites with significant differences in allele frequency (|Z| >1.65, p <0.05) between populations that are common in both populations are shown as blue circles. Sites with significant differences in allele frequency (|Z| >1.65, p <0.05) between populations that are common in only one population are shown as red circles. b | Comparison of the frequencies of 37,749 haplotypes found in African–American and European–American populations. A linear correlation of the haplotype frequency in African–Americans with the haplotype frequency in European–Americans had an R² of 0.79.