Our initial sample consisted of 1,817 DSM-IV41 OCD cases, 504 controls and 663 complete trios, genotyped using the Illumina Human610-Quadv1_B SNP array. This work was approved by the relevant IRBs at all participating sites, and all participants provided written informed consent. The majority of the control subjects genotyped as a part of this project were not screened for the absence of OCD. We also used data from 5,654 unscreened controls, previously genotyped on two different Illumina SNP arrays (Table S1).
