homodimers (Edenberg and Bosron, 2018). The difference in metabolic rate is much smaller in vivo, due to contributions of the other ADH enzymes and limitations by cofactor levels. Neumark et al. (Neumark et al., 2004) found a small (~14%) but significant difference in alcohol elimination rate between subjects of European descent with at least one ADH1B*2 allele compared to those homozygous for ADH1B*1; there was an apparently linear relationship with the number of ADH1B*2 alleles, but the number of ADH1B*2 homozygotes tested was too small for that difference to reach significance. ADH1B*2 increased the frequency of facial flushing in Asians, although the intensity of the flushing was not nearly as great as caused by ALDH2*2 alleles (Takeshita et al., 1996).
