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 (AD H3) alters the rate of alcohol metabolism. We investigated the relation amo ng the ADH3 polymorphism, the level of alcohol consumption, and the risk of myocardial infarction in a nested case-control study based on data from th e 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 p atients, 374 were matched with 2 randomly selected control subjects each an d the remaining 22 with 1 control each (total, 770 controls). The ADH3 geno type (gamma (1)gamma (1)), gamma (1)gamma (2), or gamma (2)gamma (2)) was d etermined in all subjects. We examined the relations among the level of alc ohol intake, the ADH3 genotype, and plasma high-density lipoprotein (HDL) l evels in this study population and in a similar cohort of women. Results: As compared with homozygosity for the allele associated with a fas t rate of ethanol oxidation (gamma (1)), homozygosity for the allele associ ated with a slow rate of ethanol oxidation (gamma (2)) was associated with a reduced risk of myocardial infarction (relative risk, 0.65; 95 percent co nfidence interval, 0.43 to 0.99). Moderate alcohol consumption was associat ed with a decreased risk of myocardial infarction in all three genotype gro ups (gamma (1)gamma (1)), (gamma (1)gamma (2)), and (gamma (2)gamma (2)); h owever, the ADH3 genotype significantly modified this association (P=0.01 f or the interaction). Among men who were homozygous for the gamma (1) allele , those who consumed at least one drink per day had a relative risk of myoc ardial infarction of 0.62 (95 percent confidence interval, 0.34 to 1.13), a s compared with the risk among men who consumed less than one drink per wee k. Men who consumed at least one drink per day and were homozygous for the gamma (2) allele had the greatest reduction in risk (relative risk, 0.14; 9 5 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 lev el in an independent study of postmenopausal women (P=0.02). Conclusions: Moderate drinkers who are homozygous for the slow-oxidizing AD H3 allele have higher HDL levels and a substantially decreased risk of myoc ardial infarction. (N Engl J Med 2001;344:549-55.) Copyright (C) 2001 Massa chusetts Medical Society.