Huntington Disease: Prevalence, Genetics, and Clinical Features

Huntington Disease: A Rare Neurodegenerative Disorder

Huntington disease (HD) is an autosomal dominant CAG-repeat expansion in the HTT gene. It is not common—prevalence ~5–10 per 100,000 in Western populations (~30,000 symptomatic in the U.S.).

Epidemiology

• Higher in European ancestry (~1/10,000).
• Clusters: Lake Maracaibo, Venezuela (~700/100,000); Saguenay–Lac-Saint-Jean, Quebec.
• Equal sex distribution.

Clinical Presentation

• Adult onset (30–50 years typical); juvenile onset (<20) with larger repeats.
• Triad: chorea, cognitive decline, psychiatric symptoms (depression, irritability, psychosis).
• Progressive over 15–20 years; fatal.

Genetic Testing and Counseling

Predictive testing available for at-risk adults. Requires extensive counseling due to psychological impact. No cure yet; symptomatic management (tetrabenazine for chorea, antidepressants, supportive care).