[A case of juvenile Huntington's disease presenting dystonia and confirmed by DNA analysis]

We reported a 13-year-old boy with juvenile Huntington disease diagnosed by DNA analysis. Symptoms started with dysarthria at 6 years of age, which was followed by progressive dysgraphia and gait disturbance due to dystonia from 7 years, and by epileptic seizures from 12 years. Magnetic resonance imaging revealed atrophy of the bilateral caudate nuclei and T2- and proton-weighted high intensity area in both putamina. The CAG (cytosine-adenine-guanine) trinucleotide repeat on chromosome 4 p16 was markedly expanded to 81. For a child with dystonia with mental deterioration, juvenile Huntington disease should be considered in the differential diagnosis.