The sample set included 3,328 unrelated individuals and 2,062 subjects from 864 small nuclear families, including all of the 4,061 participants in the study by Chan (2011). Of the families, 356 (41.2%) had ≥ 2 members with OD, including 229 families (26.6%) with ≥ 2 members having both OD and CD. Overlapping these were 701 (81.3%) families with ≥ 2 members with CD [thus 327 (37.9%) of the CD families had ≥ 2 members with CD but not OD]. Additionally, 54 (6.3%) families had only one affected member. Viewed differently, there were 864 probands, 1,073 siblings, 95 parents, and 30 other family members from family-based studies, and 2,685 subjects with OD and/or CD and 643 controls from case-control studies. Pedigree information was obtained for all small nuclear families that were recruited. Control subjects were screened to exclude those with a lifetime substance use disorder. Subjects with a clinical diagnosis of a psychotic disorder or gross cognitive impairment were excluded.
