an aldehyde + H2O + NAD(+) = a carboxylate + 2 H(+) + NADH Alcohol metabolism; ethanol degradation; acetate from ethanol: step 2/2. Homotetramer. Genetic variation in ALDH2 is responsible for individual differences in responses to drinking alcohol [MIM:610251]. Allele ALDH2*2 is associated with a very high incidence of acute alcohol intoxication in Orientals and South American Indians, as compared to Caucasians. Belongs to the aldehyde dehydrogenase family.