Juvenile dentatorubral-pallidoluysian atrophy: new clinical features.

Dentatorubral-pallidoluysian atrophy is a rare autosomal-dominant neurodegenerative disorder caused by an expansion of a CAG repeat in the atrophin-1 gene on chromosome 12. Dentatorubral-pallidoluysian atrophy is characterized clinically by prominent anticipation and a wide variety of symptoms that depend on age of onset and number of trinucleotide repeats. The juvenile type of dentatorubral-pallidoluysian atrophy, like Huntington's disease, is most commonly inherited via paternal transmission of the gene and most frequently presents with early-onset progressive myoclonus epilepsy with mental retardation and ataxia. We present six affected individuals with dentatorubral-pallidoluysian atrophy from a black family living in North America. This pedigree includes two severe juvenile-onset cases, one of maternal transmission and the other of paternal transmission. Both cases of juvenile-onset disease presented with autistic features and seizures. Interestingly, cranial magnetic resonance imaging performed on the more affected child revealed only mild cerebellar atrophy. The present family expands the clinical description of juvenile-onset dentatorubral-pallidoluysian atrophy and emphasizes the importance of considering dentatorubral-pallidoluysian atrophy in children with progressive myoclonus epilepsy.