[Juvenile parkinsonism in monozygotic twins].

A pair of monozygotic twins concordant for juvenile Parkinsonism are described. These twin sisters have lived together until 18 years old. Twin A noted tremor in the right hand and right-sided stiffness and slowness at the age 20. Initially, a marked improvement was shown with L-dopa treatment. However, one year after the beginning of treatment, dopa-induced dyskinesia appeared. Twin B noted tremor and right-sided stiffness and basal ganglia calcification in both patients. These twin patients suggest that genetic factors may play an important role in the cause of juvenile Parkinsonism.