Hereditary dentatorubropallidoluysian atrophy (DRPLA) is an inherited disease with an autosomal dominant trait. Its cardinal symptoms are myoclonus, epileptic seizures, ataxia, choreoathetosis, and dementia. The age of onset ranges from childhood to senescence. There is a particular correlation between the age at onset and clinical symptoms; progressive myoclonus epilepsy is a characteristic feature of DRPLA patients with juvenile onset, whereas those with late adult onset manifest cerebellar ataxia and choreoathetosis usually without myoclonus with or without epilepsy. The clinical forms of DRPLA may be classified into three subtypes: juvenile, early adult and late adult type.