The kinetic properties of ADH1B*2 and its high frequency in China and Japan (~0.70, Table 2) prompted candidate gene studies founded upon the hypothesis that a variant that affects alcohol metabolism would affect drinking behavior and thereby the risk for AD. Thomasson et al. (Thomasson et al., 1991) found the protective effect of ADH1B*2 was strong (allelic odds ratio (OR) = 0.33) in male Chinese, and independent of that of ALDH2*2 (the inactive aldehyde dehydrogenase; see below). This was followed by many candidate gene studies and meta-analyses in Asian populations. Wherever the frequency of ADH1B*2 was high enough, the same result was obtained: presence of a single ADH1B*2 allele strongly reduced the risk for alcoholism, and in those homozygous for ADH1B*2, the risk was even further reduced (Chen et al., 1999b, Luczak et al., 2006, Whitfield, 2002, Li et al., 2011, Zintzaras et al., 2006, Park et al., 2013)3.
