Clinical features of hereditary spinocerebellar ataxia diagnosed by molecular genetic analysis.

OBJECTIVE To assess the frequency and clinical features of different types of hereditary spinocerebellar ataxia in Hong Kong. DESIGN Cross-sectional study using a questionnaire and clinical examination, with the majority of the information retrospectively collected. SETTING Three regional hospitals, Hong Kong. PARTICIPANTS All patients with spinocerebellar ataxia that was confirmed by molecular genetic tests between January 2001 and October 2003. MAIN OUTCOME MEASURES History, latest physical examination results, clinical investigation results, and genetic profiles. RESULTS A total of 16 Chinese patients had received diagnoses of spinocerebellar ataxia. These patients had spinocerebellar ataxia type 1 (n=3), spinocerebellar ataxia type 3 (Machado-Joseph disease; n=12), and dentatorubro-pallidoluysian atrophy (n=1). The most common manifestation was ataxia (15/16), followed by pyramidal signs (12/16). Other features such as bulbar dysfunction, ophthalmoplegia, neuropathy, and cognitive impairment were present but variable. CONCLUSIONS The clinical manifestations of different types of spinocerebellar ataxia overlap, and genetic study is necessary to confirm the diagnosis. The frequency of spinocerebellar ataxia type 3 is greater than that of other types among these Chinese patients. The age of onset of this type may correlate inversely with the number of CAG repeats.