Objective To investigate the differences and similarities in the clinical characteristics of juvenile-type and adult-type dentatorubral-pallidoluysian atrophy (DRPLA).Methods The clinical data of 3 patients with juvenile DRPLA and 1 patient with adult DRPLA were collected, and their clinical manifestations, imaging characteristics, electroencephalogram (EEG) results, and DRPLA gene CAG repeat numbers were analyzed comparatively.Results The mean age of onset of the 3 patients with juvenile DRPLA was 13 years, and these patients all had a history of myoclonus and epilepsy and the symptoms of mental retardation, marked cerebellar ataxia, involuntary movement, and psychosis. The age of onset of the patient with adult DRPLA was 22 years, and the patient had a history of myoclonus and epilepsy, and the symptoms of memory deterioration, mild cerebellar ataxia, and tremors in both hands, but without psychosis. Magnetic resonance imaging showed marked atrophies in the brainstem, the cerebellum, and the cerebral cortex and symmetric white matter degeneration in patients with juvenile DRPLA, and only mild atrophies in the brainstem and the cerebellum was observed for adult DRPLA. EEG background for juvenile and adult DRPLA was slow wave rhythm and normal rhythm, respectively. DRPLA gene detection showed that the numbers of CAG repeats in 3 cases of juvenile DRPLA were 15/64, 17/65, and 15/68, respectively, and that the number of CAG repeats in the case of adult DRPLA was 17/62.Conclusions DPRLA has obvious clinical heterogeneity, and the number of CAG repeats is associated with the age of onset and clinical manifestations. Specific gene detection can be performed for juvenile patients with myoclonus, epilepsy, ataxia, and mental retardation to raise the detection rate of juvenile DRPLA and avoid missed diagnosis.