Spinocerebellar ataxia type 6 in relation to CAG repeat length.

The purpose of the present study was to assess the relationship between clinical characteristics of spinocerebellar ataxia type 6 (SCA6) and CAG repeat length.We examined clinical symptoms of 54 patients with SCA6. CAG repeat length was compared among subgroups divided by clinical manifestations.The major symptom was progressive cerebellar ataxia. Truncal or limb ataxia, dysarthria, and nystagmus were observed in more than 80% of the patients. In analysis of CAG repeat length in patients with different types of nystagmus, CAG repeat length was the longest when both upbeat and downbeat nystagmus existed (P < 0.01). In addition, CAG repeat length was longer when the initial symptom was ataxic gait and was shorter when the initial symptom was dysarthria or ocular symptom (P < 0.05).Clinical features of SCA6 might be influenced by the length of abnormal CAG repeat.