Genetic variation in alcohol dehydrogenase and the beneficial effect of moderate alcohol consumption on myocardial infarction

Background A polymorphism in the gene for alcohol dehydrogenase type 3 (ADH3) alters the rate of alcohol metabolism. We investigated the relation among the ADH3 polymorphism, the level of alcohol consumption, and the risk of myocardial infarction in a nested case-control study based on data from the prospective Physicians' Health Study. Methods We identified 396 patients with eligible newly diagnosed cases of myocardial infarction among men in the Physicians' Health Study. Of these patients, 374 were matched with 2 randomly selected control subjects each and the remaining 22 with 1 control each (total, 770 controls). The ADH3 genotype (y1y1, y1y2, or y2y2) was determined in all subjects. We examined the relations among the level of alcohol intake, the ADH3 genotype, and plasma high-density lipoprotein (HDL) levels in this study population and in a similar cohort of women. Results As compared with homozygosity for the allele associated with a fast rate of ethanol oxidation (y1), homozygosity for the allele associated with a slow rate of ethanol oxidation (y2) was associated with a reduced risk of myocardial infarction (relative risk, 0.65; 95 percent confidence interval, 0.43 to 0.99). Moderate alcohol consumption was associated with a decreased risk of myocardial infarction in all three genotype groups (y1y1, y1y2, and y2y2); however, the ADH3 genotype significantly modified this association (P=0.01 for the interaction). Among men who were homozygous for the y1 allele, those who consumed at least one drink per day had a relative risk of myocardial infarction of 0.62 (95 percent confidence interval, 0.34 to 1.13), as compared with the risk among men who consumed less than one drink per week. Men who consumed at least one drink per day and were homozygous for the y2 allele had the greatest reduction in risk (relative risk, 0.14; 95 percent confidence interval, 0.04 to 0.45). Such men also had the highest plasma HDL levels (P for interaction = 0.05). We confirmed the interaction among the ADH3 genotype, the level of alcohol consumption, and the HDL level in an independent study of postmenopausal women (P=0.02). Conclusions Moderate drinkers who are homozygous for the slow-oxidizing ADH3 allele have higher HDL levels and a substantially decreased risk of myocardial infarction.