For most subjects, we obtained DNA from immortalized cell lines, but for a small proportion of the subjects, DNA was obtained directly from blood or saliva. A total of 6,008 SNPs were genotyped by the Center for Inherited Disease Research (CIDR) using the Illumina Linkage IVb Marker Panel (http://www.cidr.jhmi.edu). An additional 266 individuals were genotyped at Yale (Keck Center) using the 6,090 SNP Illumina Infinium-12 Human Linkage Marker Panel. The analyses were limited to the autosomal SNPs, and 5,636 and 5,735 SNPs were used from the first and second panels, respectively. Among the SNPs in the two panels, there were 4,518 SNPs in common across the two platforms, and the common SNPs were used for the following quality control and analyses. Allele frequencies were calculated and HWE was examined in each population by means of PLINK software [Purcell et al., 2007] using a set of unrelated subjects (355 EA and 384 AA subjects were randomly selected, one per family). Any SNP that had a genotyping rate ≤0.95, a minor allele frequency (MAF) ≤0.1, or was not in Hardy–Weinberg equilibrium (HWE)
