In only one study,49 results were reported that were not consistent with OC illness and/or features being familial. In this study, a relative was considered affected only if they had been hospitalized for OC illness. Using this criterion, no significant increase of OC illness among first-degree relatives of 144 obsessional neurotics was observed, although an increased rate of psychiatric illness among these relatives was reported. Unfortunately, no information about OC symptomatology among relatives who were not hospitalized was provided.
