used to assign diagnoses, there was not a significant increase in the occurrence of OCD among the relatives. The rate of OCD and subclinical OCD for interviewed relatives when no informant information was used in the diagnostic process was 5.4% compared with 1.7% among controls (P=0.17). On the other hand, the rate of OCD and subclinical OCD among interviewed relatives when additional informant data were used was 8.9% compared with only 1.7% among controls (P=0.02). These investigators concluded that “evidence of familial transmission of OCD was found only when diagnoses were made using information from the proband about the relative.” As an explanation for these differences, these authors suggest that since individuals with OCD can be quite secretive about their symptoms, it is possible that upon direct interview, they might deny OC symptomatology. This could be particularly important in the case when the individual being interviewed has never sought treatment for their OC symptoms. On the other hand, it is also possible that an affected relative who has sought treatment or proband may “over-report” symptoms in their relatives. In the Lipsitz et al59 study, family history information was only collected from the affected probands, all of whom had sought treatment,
