Dominantly inherited spinocerebellar ataxias (SCAs) are a group of the heterogenous neurodegenerative diseases that are characterized by chronic progressive cerebellar ataxia associated with various combinations of other neurological signs. Clinical classification is difficult because of the phenotypic overlap. With the evolution of molecular genetics, the loci and mutations for many of the ataxias have been identified, allowing more definitive molecular classification.

We experienced 42 years-old man who presented with progressive both lower leg weakness, dysarthria, ataxia, ophthalmoplegia, and nystagmus. The family history was remarkably suspicious. We could not observe the upper extremity weakness, definite evidences of peripheral neuropathy and myopathy in electrodiagnosis. No abnormal findings in blood chemistry and brain MRI. We performed polymerase chain reaction (PCR) and polyacrylamide gel electrophoresis (PAGE) analysis, found that his gene contained expanded CAG repeats (CAG repeat number was 72). Although no effective treatment exists for most the ataxic syndromes, the accurate diagnosis and the genetic counseling are often important to the patient's family for prognostication.