Genetics and the risk for alcoholism.

The importance of genetic factors in alcoholism is supported by the familial nature of this disorder, the significantly higher concordance rate in identical than in fraternal twins, and the fourfold higher risk for children of alcoholics, even when adopted out at birth. Based on this evidence, the search is under way to identify possible genetically influenced factors that might contribute to the alcoholism risk. Studies of populations at high risk for the future development of alcoholism (eg, sons of alcoholics) have revealed a probable decreased intensity of reaction to modest doses of ethanol, a possible decreased amplitude of the P300 wave of the event-related potential, and a possible decreased amount of alpha-wave activity on the background cortical electroencephalogram. The implications of these and other findings and their impact on the practice of medicine are explored.