GTP CYCLOHYDROLASE-I ACTIVITY IN MONONUCLEAR BLOOD-CELLS IN JUVENILE PARKINSONISM

GTP cyclohydrolase I activity in mononuclear blood cells from patients with juvenile parkinsonism (JP) was found to be normal compared to he althy controls. The normal activity in JP contrasts strongly with the decreased activity of 2-20% normal levels in hereditary progressive dy stonia with marked diurnal fluctuation (HPD) or dopa responsive dyston ia (DRD). The result indicates that the decreased dopamine level in th e basal ganglia in JP is not due to decreased activity of GTP cyclohyd rolase I, the enzyme for the biosynthesis of the tetrahydrobiopterin c ofactor of tyrosine hydroxylase (TH), and the enzyme activity in monon uclear blood cells could be a reliable method for differential diagnos is between JP and HPD/DRD.