[Case of dentatorubral-pallidoluysian atrophy with onset of psychomotor retardation in infancy].

: We report a patient with dentatorubral-pallidoluysian atrophy (DRPLA). She developed normally until the age of 6 month, when she could sit by herself. However, her psychomotor development was subsequently slow with gradual appearance of equilibrium disturbances and involuntary movements such as polymyoclonia and chorea. Her development deteriorated after myoclonic seizures developed at 4.5 years of age. Electroencephalograms showed semi-continuous bursts of diffuse irregular spike-wave complexes and MRI of the brain showed atrophy of the cerebellum and brainstem, and high signal intensities in the posterior periventricular triangle portion on T2-weighted images. Gene analysis performed at the age of 6 years revealed an expanded CAG repeat (17/74) at the DRPLA locus. The CAG repeat size was larger in this case than in cases of the adult and juvenile types with later onset, suggesting a correlation between repeat length and age at onset. Genetic examination of the family members was not performed because of her mother's fear and emotional confusion.