There also are three alleles of the ADH1C gene (Table 2). ADH1C*1 encodes the γ1 subunit that has Arg at position 272 and isoleucine (Ile) at position 350. ADH1C*2 encodes the γ2 subunit that shows two differences compared with ADH1C*1—it codes for a glutamine (Gln) at position 272 and a valine (Val) at position 350. In almost all cases, these two SNPs occur together (i.e., are in very high linkage disequilibrium [LD]). ADH consisting of two γ1 subunits (i.e., the γ1γ1 homodimeric enzyme) has a turnover rate that is about 70 percent higher than that of the γ2γ2 enzyme. ADH1C*Thr352 encodes a subunit with threonine at position 352; it has been described in Native Americans (Osier et al. 2002a). However, the protein has not been studied.
