[A case of adult-onset Huntington disease presenting with spasticity and cerebellar ataxia, mimicking spinocerebellar degeneration].

We report an adult-onset case of Huntington disease presenting with spasticity and cerebellar ataxia. The patient, a 47-year old woman, was admitted to our clinic because of progressive involuntary movements. Her elder brother suffered from the similar symptoms. Neurologically, she had quick temper, dementia, generalized chorea, spasticity and truncal ataxia. MRI demonstrated atrophy of caudate, midbrain, pons and cerebellum. From these clinical and MRI findings, she was suspected to have a form of spinocerebellar degeneration (SCD), particularly DRPLA. However, DNA analysis showed CAG repeats in huntington gene was expanded (47/20). Accordingly she was diagnosed as having adult-onset Huntington disease, mimicking SCD. This case indicates Huntington disease may present atypical clinical features and it is crucial to determine CAG repeat size in huntington gene for the patient with dementia and/or movement disorders, etiology of which is unknown. The relationships between clinical phenotypic variations and huntington gene expression are not determined.