The COGA sites began with recruitment of AUD probands from inpatient and outpatient treatment facilities and administered a poly‐diagnostic interview, the Semi‐Structured Assessment for the Genetics of Alcoholism (SSAGA), 66 , 67 and targeted families with a high density of first‐degree relatives with alcohol dependence. Comparison families were recruited within the same communities. 68 To approximate the laboratory sample, COGA were included in analyses only if they were of European ancestry, between the ages of 21 and 28 at their most recent interview, and ever drank at least one full alcohol beverage. One person per extended family corresponding to the participant with the lowest identification number in the age range was retained. The final COGA sample contained N = 644 individuals, with 65% having a parent with AUD. FHD was computed in the COGA sample 58 in the same way as the laboratory sample. See Supporting Information for more discussion of the COGA sample.
