FAMILIAL AGGREGATION OF SCHIZOPHRENIA-LIKE SYMPTOMS IN HUNTINGTONS-DISEASE

An increased incidence of schizophrenia-like symptoms in Huntington's disease (HD) has been well-documented in the past, The reasons for thi s association, however, have never been explained. At the University o f Washington Medical Genetics Clinic, we had the opportunity to evalua te a unique juvenile-onset HD proband who had schizophrenia-like sympt oms. This patient was referred to our clinic because of new onset of s omatic delusions and command auditory hallucinations early in the cour se of her illness. Since we had already evaluated other affected indiv iduals in her family, we selected another family with a nonpsychotic j uvenile-onset proband for comparison. Using these two families in a sm all case-control study, we investigated the following hypotheses which could explain the association between schizophrenia-like symptoms and HD: first, schizophrenia-like symptoms may be related to the number o f CAG repeats in the HD gene; second, schizophrenia-like symptoms may segregate in certain HD families, for unknown reasons; and third, ther e may coincidentally be an unrelated gene for schizophrenia in certain HD families, Comparisons of clinical characteristics and the HD genot ype showed that family history of schizophrenia-like symptoms segregat ed with the HD gene; however, age of onset of HD, size of CAG; repeat, and sex of the transmitting parent were not associated with psychotic symptoms. Further genetic and neurobiological studies are necessary t o investigate the potential mechanism underlying this association, Am. J, Med, Genet, (Neuropsychiatr. Genet.) 81:323-327, 1998. (C) 1998 Wi ley-Liss, Inc.