Alcohol related phenotypes were derived using the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) designed for genetic studies of alcoholism16–18. The SSAGA comprehensively assesses alcohol, nicotine and drug use and has high reliability and validity16–18. Alcohol and drug dependence were defined using DSM-IV criteria8 and nicotine dependence was characterized using the Fagerström Test for Nicotine Dependence (FTND)13.
