As noted in the discussion of twin studies, a number of investigators have examined family data to test the hypothesis that other disorders may be significantly increased among relatives of OCD probands. Additional analyses of the Hopkins OCD Family Study56 were reported.6667 Bienvenu et al66 explored OC-spectrum disorders among proband relatives and found significantly higher rates of BDD (OR=5.4), somatoform disorders (OR 3.9), grooming disorders (OR=1.8), and all spectrum disorders combined (OR=2.7). Similarly, Grados et al67 explored OCD comorbidity and found an increased prevalence of tic disorders among proband relatives versus control relatives. There was also an association between earlier age of OCD onset and tic comorbidity. These findings are consistent with those reported earlier.29,38,41 These findings suggest that there may be at least three different types of OCD: (i) one that is inherited and related to TS; (ii) one that is inherited and not related to TS but possibly related to anxiety; and (iii) one that is not familial.
