To uniformly cover the whole gene including 5′- and 3′-untranslated regions, five tagger SNPs were selected spanning the APBB1 gene, with an average inter-SNP distance of 5 kb per SNP, and were genotyped using the Illumina BeadChip system at the Center for Inherited Disease Research (CIDR) at Johns Hopkins University. The PedCheck program (O’Connell and Weeks 1998) was used to identify any possible errors, such as inconsistent Mendelian inheritance or other genotyping errors. Among over than 10,000 assays, 120 inconsistencies (83 in the AA sample, 1.24%; and 37 in the EA sample, 1.11%) were detected and excluded from the following association analyses. To further verify the quality of SNP-typing, we checked any significant departures from Hardy-Weinberg Equilibrium (HWE). Except for SNP rs1552513, which departed slightly from HWE in the AA sample, all other SNPs were in HWE (Table 1). Pair-wise Linkage Disequilibrium (LD) (Fig. 1) among all SNPs was determined using the Haploview program (Barrett et al. 2005), based on haplotype blocks as defined by Gabriel et al. (2002). One block formed by rs10839562-rs1079199 in the EA sample was detected; no significant LD blocks were detected for the AA or pooled samples.
