The Collaborative Study on the Genetics of Alcoholism (COGA) was initiated in 1989 with funding from the National Institute on Alcohol Abuse and Alcoholism (NIAAA)9–10. Subjects were recruited by seven sites across the United States. Alcohol dependent probands were systematically recruited from treatment facilities, and relatives were interviewed. Comparison families were drawn from the same communities. A case-control sample of biologically unrelated individuals was drawn from the sample11. All cases met DSM-IV criteria for alcohol dependence. Control subjects were defined as individuals who consumed alcohol, but did not meet any definition of alcohol dependence or alcohol abuse, or abuse or dependence on other drugs (except nicotine). For this study 1800 COGA case-control subjects were studied, including 1139 DSM-IV alcohol dependent cases and 661 non-alcohol dependent controls.
