Development of the nosological analysis of juvenile parkinsonism

In the nosological viewpoint concerning diseases with a pathophysiological dysfunction of the nigro-striatal dopaminergic system, juvenile parkinsonism (JP) is discussed in this paper in relation to hereditary progressive dystonia (HPD) and Parkinson's disease (PD). Most cases of JP have dystonia with parkinsonism, which is the main symptom of HPD. In the symptomatological analysis of complication with dystonia, an interesting observation arose as regards on the anatomical and functional development of the basal ganglia through patients with childhood onset HPD and JP. Genetic analysis revealed the disease entity of HPD to be an abnormality of the GTP-CH I gene. Consequently, it has been clarified that clinical differences between HPD and JP were not merely derived from differences in developmental processes. Furthermore, the autosomal recessive type of JP (AR-JP) was confirmed to be a disease entity by the detection of an abnormality of the 'parkin' gene. The nosological controversy about JP and PD in the clinical standpoint has been clarified. However, as more than half of patients with JP do not carry a mutation in the 'parkin' gene, more investigations concerning nosological entities should be carried out. The absence of Lewy bodies in most patients with AR-JP has been confirmed to be a characteristic neorupathological finding as compared with those with typical PD pathology. In this paper, we discuss the above findings.