DSM-IV AD was used as a secondary phenotype, to enable comparison with other studies in the literature. Given the wide age range of the subjects included in the analysis and the fact that many had not passed through the age of risk for an alcohol use disorder (AUD), the following algorithm was developed to reach the final diagnosis after considering all evaluations. Individuals aged 15 years or older who met DSM-IV criteria at any evaluation were classified as alcohol dependent. Individuals 23 years and older who drank but did not meet criteria for AD on any adult SSAGA were classified as unaffected. Individuals who did not consume alcohol, were under the age of 15 years at all evaluations, or were age 15 through 22 years old and did not meet DSM-IV criteria, were classified as unknown and were removed from subsequent analyses – this avoids ascribing an unaffected status to an adolescent or young adult who may be at high genetic risk but not yet past the peak period of vulnerability. There were 684 subjects in the 118 extended families
