The enzyme activity of mutant ALDH2 homozygous and heterozygous genotypes is 17%–38%, respectively, that of the normal ALDH2 genotypes, and presence of the ALDH2 gene mutation might play a critical role in coronary heart disease, myocardial infarction, heart failure, cancer, and Alzheimer disease, among others (36–42). Here, ALDH2 is linked to Alzheimer disease.