Juvenile Huntington's disease: report of one case.

Huntington's disease (HD) is caused by mutation of the IT 15gene (chromosome 4p16.3), with elongation of (CAG) n repeats. Most juvenile Huntington disease patients acquire the genetic defect through paternal transmission due to amplification of the repeat number during spermatogenesis, and thus causing early age of disease onset and increased disease severity. We here report one case that instead of choreoathetosis presents symptoms of developmental regression, such as seizure and rigid/bradykinesia. EEG showed occipital dominant 4-5 Hz high-amplitude spike-wave activities. MRI showed advanced atrophy and abnormal increase in signal intensity on T2-weighted and proton-density-weighted images of the caudate nuclei and putamina early in the course. The clinical diagnosis is confirmed by PCR study of HD (CAG) n repeats. This is the first case of juvenile Hunington's disease reported in Taiwan.