Only three genome -wide linkage studies of OCD have been completed to date.135-137 No study yielded genomewide significance; however all studies suggested regions of interest for future research. Hanna et al136 completed a genome scan on seven families which included 66 individuals. All families had been identified through childhood OCD probands. All but one of the relatives were directly assessed with structured psychiatric interviews and 32 received diagnosis of lifetime OCD.
