ADH1C also has cSNPs, of which ADH1C*1 and ADH1C*2 are the most studied. These two alleles differ at two sites, resulting in two amino acid changes: the enzyme encoded by ADH1C*1 (γ1-ADH) has Arg at position 272 and isoleucin (Ile) at position 350, whereas that encoded by ADH1C*2 (γ2-ADH) has glutamine (Gln) at position 272 and valine (Val) at position 350 (Osier et al. 2002).2 The kinetic differences between γ1-ADH and γ2-ADH are smaller than those between the ADH1B isozymes (table 1). Studies in Asian populations have shown an association between ADH1C alleles and alcoholism, but the protective effect of ADH1C*1 in that population may be explained in large part by its coinheritance with the ADH1B*2 allele. A SNP in the ADH1C gene that is always inherited together with (i.e., is in complete linkage disequilibrium) with one of the amino acid changes at this locus was associated with alcoholism in two GWASs candidate gene substudies on people of European descent, but the difference did not reach statistical significance for genome-wide analyses (Kendler et al. 2011; Treutlein et al. 2009). The
