Association of the ADH2*3 Allele With A Negative Family History Of Alcoholism in African American Young Adults

BACKGROUND: Two of the class I alcohol dehydrogenase (ADH) genes (ADH2 and ADH3) encode for multiple isozymes that differ in their kinetic properties. Polymorphisms at both of these gene loci have been linked to alcoholism and/or alcohol-induced disabilities in some populations. At the ADH2 locus, three polymorphisms are present (ADH2*1, ADH2*2, ADH2*3). ADH2*3 allele codes for a high Km and Vmax variant that has been reported to occur exclusively in African Americans and some tribes of Native Americans. In African Americans, the presence of the ADH2*3 allele is associated with protection from alcohol-related birth defects. However, its relationship to risk for alcoholism in African Americans remains relatively unexplored. METHODS: The participants were 97 African American young adults (18-25 years old). A structured interview was used to gather information on demographics, psychiatric diagnoses, personal drinking and drug use history, and familial history of alcohol use disorders. A blood sample was obtained from each participant and leukocyte DNA extracted and genotyped for the presence of ADH2*3 alleles. The specific aim of the study was to investigate the associations between the presence of the ADH2* 3 allele and personal and family history of alcohol use/abuse. RESULTS: Thirty participants (31%) had at least one ADH2*3 allele and two were homozygous for the allele. A significant association between the presence of an ADH2*3 allele and a negative family history of alcoholism was uncovered (p < 0.04). No significant associations of an ADH2*3 allele with personal history of alcohol use disorders or with current drinking were found; however, power to detect associations was limited in this population because half the population did not drink regularly. CONCLUSIONS: Because family history of alcoholism is one of the best predictors of the development of alcohol use disorders, this pilot study suggests that, in this sample of African American young adults, the ADH2*3 allele may be associated with a lowered risk for the development of alcoholism.