Alcohol dependence (alcoholism), the most severe alcohol use disorder, is a complex genetic disease. Alcoholism has long been noted to run in families, but that alone is not sufficient to demonstrate that genetic factors contribute to risk. Many independent lines of evidence point to genetic contributions to its etiology. Adoption studies show that alcoholism in adoptees correlates more strongly with their biological parents than their adoptive parents10-13. Twin studies in the US and Europe suggest that approximately 45-65% of the liability is due to genetic factors14-17. Animal studies also demonstrate genetic liability; mice and rats have been selectively bred for many traits associated with alcohol dependence, including alcohol preference, alcohol sensitivity, and withdrawal sensitivity18, 19. The ability to genetically select for these traits demonstrates that there are genetic bases for them, and that different genes contribute to different aspects of the phenotype. Taken together, there is overwhelming evidence that genetic variations contribute to the risk for alcohol dependence.
