The COGA dataset provided for GAW14 contained 1,614 family members in 143 families with different sizes. Each family was ascertained from an alcoholic proband in a treatment program. Self-reported ethnicity in this study population included American Indian, Asian, Pacific Islander, Black Hispanic and non-Hispanic, and White Hispanic and non-Hispanic. From the list of alcohol-related phenotypes available in the dataset, we chose the age at onset for alcohol dependence (ALDX1). ALDX1 was defined as lifetime diagnosis [3] of alcohol dependence by DSM-III-R (Diagnostic and Statistical Manual of American Psychiatric Association-Revised) [4] criteria and definitive alcoholism by Feighner [5] criteria. Only individuals meeting both criteria were considered affected in this study.
