acetaldehyde concentrations after alcohol consumption 6- and 19-fold higher than homozygous common-allele individuals, respectively (Mizoi et al. 1994). Due to delayed oxidation in individuals with the 504lys allele, these individuals have high blood acetaldehyde concentrations, which can cause adverse reactions sufficient to deter drinking. Some individuals with a high daily intake of alcohol develop alcohol-induced medical diseases, e.g., alcoholic cirrhosis, which occurs in around 10% and hepatitis in 10–35% (Grant et al. 1988) of AD individuals. It was hypothesized that the 504lys allele could decrease the risk of AD and consequently influence risk for alcohol-induced medical illnesses, including alcohol liver disease, cirrhosis, and pancreatitis (Thomasson et al. 1991; Yoshida et al. 1991). In addition, genome-wide association studies showed that rs671 was associated with mean corpuscular hemoglobin concentration (Kamatani et al. 2010) and esophageal squamous cell carcinoma (Cui et al. 2009). Other ALDH2 variants were found to be associated with blood pressure (Kato et al. 2011) or upper aerodigestive tract cancers (McKay et al. 2011).
