Juvenile Huntington disease in the Netherlands.

Juvenile Huntington disease (JHD) patients are distinguished from adult patients by an age at onset of less than 20 years. Investigating patients in our own database, we examined the proposition derived from studies in world literature that JHD should not be viewed as a separate clinical entity but rather as a manifestation of the rigid variant of the disease. Of 53 patients with JHD recorded in the Leiden Roster for Huntington Disease, relationships between sex, age at onset, duration of illness, maternal or paternal inheritance, motor symptom, first clinical features, and characteristics during the disease course, were obtained from the patients' files, and investigated. Although chorea is present in JHD, patients more often developed rigidity. Paternal inheritance, early dementia, epilepsy/myoclonus, and tremor during the disease course are confined for the most part to the rigid cases. A shorter duration of illness was evident in male patients with rigid JHD who inherited the disease from their father and developed their first disease feature at a younger age. The recognition of JHD as a distinct clinical entity does not appear to be warranted. Therefore, we propose, in accordance with other investigators, that rigid JHD be considered a clinical variant with special features.