Late onset ataxia phenotype in dentatorubro-pallidoluysian atrophy (DRPLA)

We clinically and genetically studied three patients in a family with dentatorubro-pallidoluysian atrophy (DRPLA). The proband patient had 58/24 CAG repeat alleles of the DRPLA gene (normal less than or equal to 34 repeats). Cerebellar ataxia first developed in the 6-71(th) decades and was the predominant feature for more than 10 years in all three, after which two of them manifested dementia and choreiform movements in the advanced stage. Atrophy of the cerebellum and brain stem an CT or MRI had suggested dominant spinocerebellar ataxia as a diagnosis in their ataxia-predominant stage, with a diagnosis of DRPLA being impossible based on the clinical findings alone. Our experience implies that DRPLA must be taken into account in the differential diagnosis of late onset ataxic disorders, since it can easily be overlooked.