Parkinson's disease in monozygotic twins

Abstract

Recent studies of twins have demonstrated an unexpectedly low concordance of Parkinson's disease in monozygotic twins. Only two monozygotic twin pairs concordant for it have been reported. However, both pairs were atypical because of an early age at onset and other unusual features. We studied a monozygotic twin pair concordant for typical Parkinson's disease. The brothers have lived apart for forty years. The onset of tremor occurred three months apart, at age 71. The progression of the symptoms has been identical. Although one of the twins is more severely affected, both have typical manifestations of Parkinson's disease that respond well to dopaminergic medication. The occurrence of Parkinson's disease in these monozygotic twins suggests that genetic susceptibility is important in the tremor-dominant variety of Parkinson's disease.