The International OCD Foundation Genetics Collaborative, a multi-national group established to discover genetic variation predisposing to OCD, has conducted the most extensive genetic study of OCD to date (half a million chromosomal locations in 1,465 affected individuals, 5,557 ancestry-matched controls, and 400 trios). Genome-wide significant evidence of association was found in the trios on chromosome 20 (rs6131295) near the gene encoding transcription factor BTBD3, but this finding was not significant when combined with the case-control data. Interestingly, the best results from this combined analysis were in genes (FAIM2 and ADCY8) with human brain expression patterns that are highly correlated with genes regulated by rs6131295 (BTBD3, DHRS11 and ISM1). This suggests an interrelated set of genes that may predispose individuals to OCD. This study by Dr. Knowles and his team aimed to extend these initial findings by adding at least 1,348 OCD-affected individuals and 1,349 ancestry-matched controls to unequivocally identify a genetic locus (gene) for OCD and to provide a set of molecular targets for rational development of small molecule therapeutics for OCD.