[Recent progress of research on hereditary spinocerebellar degeneration]

Hereditary spinocerebellar degeneration consist of a cluster of heterogenous disorders. Based on clinical features, neuropathological findings and inheritance mode, these disorders have been classified into several entities. In the Japanese, olivo-ponto-cerebellar atrophy (OPCA), Machado-Joseph disease (MJD) and dominant cortical cerebellar atrophy (CCA) are the most popular forms of ataxia. Recent linkage analyses have revealed the locations of these genes; OPCA maps either on 6p23 (SCA1) or on 12q23 (SCA2), and MJD on 14q. The chromosomal assignment of these genes has resulted in development of a new classification of ataxia and has opened a new era of ataxia research.