The familial phenotype of obsessive-compulsive disorder in relation to ticdisorders: The Hopkins OCD family study

Background: Obsessive-compulsive disorder (OCD) and tic disorders have phen omenological and familial-genetic overlaps. An OCD family study sample that excludes Tourette's syndrome in probands is used to examine whether tic di sorders are part of the familial phenotype of OCD. Methods: Eighty case and 73 control probands and their first-degree relativ es were examined by experienced clinicians using the Schedule for Affective Disorders and Schizophrenia-Lifetime Anxiety version. DSM-IV psychiatric d iagnoses were ascertained by a best-estimate consensus procedure. The preva lence and severity of tic disorders, age-at-onset of OCD symptoms, and tran smission of OCD and tic disorders by characteristics and type of proband (O CD + tic disorder, OCD - tic disorder) were examined in relatives. Results: Case probands and case relatives had a greater lifetime prevalence of tic disorders compared to control subjects. Tic disorders spanning a wi de severity range were seen in case relatives; only mild severity was seen in control relatives. Younger age-at-onset of OCD symptoms and possibly mal e gender in case probands were associated with increased tic disorders in r elatives. Although relatives of OCD + tic disorder and OCD - tic disorder p robands had similar prevalences of tic disorders, this result is not conclu sive. Conclusions: Tic disorders constitute an alternate expression of the famili al OCD phenotype. (C) 2001 Society of Biological Psychiatry.