The third locus is for the alcohol dehydrogenase ADH1B gene, where a nonsynonymous coding genetic variant rs1229984 (Arg47His) is reported to be under positive selection in East Asia (Han, et al., 2007). Allele A is found at 0.77 frequency in HapMap CHB and JPT, but is absent in CEU and YRI samples. Since genotypes for rs1229984 were not available for our sample set, allele A for rs10008281, a nearby SNP in strong LD with allele T for rs1229984 (r2=0.53 in HapMap CEU samples) was used for modeling. [Note: since the trait is modeled on the proxy SNP, the performance of AIM sets should be unaffected by the r2.] Individuals homozygous for allele A for rs10008281 were designated as surrogate cases, while individuals with A/G and G/G genotypes were designated as surrogate controls (allele A is 0.82 in CHB and 0.83 in JPT, and 0.28 in CEU and YRI).
