Table 1

Adult Onset

Juvenile Onset

Prevalence

4–10/100,000 population

0.5–1/100,000 population

Inheritance

Autosomal dominant

Autosomal dominant (80-90% inherit HD from their father

Age at onset (years)

35-45 (2-80)

less than 15

Initial signs

personality changes, chorea, decreased coordination

personality changes, school failure, bradykinesia, dystonia, rigidity

Late signs

progressive cognitive decline, dysarthria, abnormal eye movements, choreoathetosis, dystonia, rigidity

progressive cognitive decline, dysarthria, abnormal eye movements, dystonia, rigidity, tremors, seizures, ataxia, rare chorea