The initial OCD sample consisted of 1,565 patients and 437 parent-child trios (n=406 independent families, 31 affected siblings) recruited from 22 sites in the US, Canada, Europe, Latin America, and South Africa, predominantly through OCD specialty clinics. In total, 1,971 independent patients with OCD (including trio probands) were eligible for analysis. 1,613 patients with OCD (82%) survived quality control (QC), and were included in the final analyses. Mean age of OCD symptom onset was 13.8 years (SD=9.1). 327 cases and 21 affected siblings had parents available for de novo analysis (n=348 total trios). TS or chronic tics (CT) were assessed in 57% of OCD probands using DSM-IV-TR criteria. Of those assessed, TS was present in 10% of patients with OCD, and an additional 5% had CT.
