In order to evaluate whether there are other polymorphisms in strong linkage disequilibrium (LD) with this SNP, haplotype construction, counting, and LD block defining over a broader genomic region that includes ALDH2 were performed separately based on the published genotype data of 90 Asian (Chinese and Japanese) samples and 30 CEPH trios (Utah residents) from HapMap release 23a (http://ftp.hapmap.org/genotypes/2008-03/rs_strand/non-redundant). The multiallelic D’ was computed by performing a series of pairwise D’ calculations using each haplotype in turn as an allele, with all other haplotypes at the locus serving as the other allele. This was then repeated for each haplotype at each locus and averaged by haplotype frequency. Maximum likelihood haplotype blocks were calculated using the EM algorithm (Excoffier and Slatkin 1995). In addition, the genotype data from the 1000 Genomes Project were also used to calculate and build the LD block (Johnson et al. 2008).
