[Clinical study of gene locus heterogeneity in hereditary olivopontocerebellar atrophy (OPCA)--report of 2 pedigrees affected with non SCA1 type OPCA].

From the linkage study of D6S89, we previously reported that hereditary OPCA in Japan is genetically heterogenous. Two pedigrees, P2 and P35, reported in this report, were not linked to D6S89. In order to examine possible correlation between OPCA genotypes and disease phenotypes, we studied clinically eight cases in these two pedigrees. One autopsied case in pedigree P2 was proven to have marked neuronal degeneration in the inferior olivary nuclei, pontine nuclei, cerebellar cortex, and substantia nigra. Dentate nucleus and oculomotor nuclei were free from neuronal degeneration. Clinical features of those 8 patients were fairly uniform, characterized by cerebellar ataxia, hypoactive DTR, and slow eye movement. Parkinsonism or choreiform movements were observed in one patient, respectively. Pupillary dilatation, twitching of face and tongue, limb amyotrophy were observed in patients of advanced stages. However, these signs were not dominating nor common throughout clinical course. None of our cases showed hyperactive DTR, limb spasticity, or external ophthalmoparesis. On the other hand, these latter signs were popular in SCA1 so far as reviewing the literature. The present study showed that there was possible correlation between genotypes and phenotypes in hereditary OPCA.