Med in Small Doses - Huntington's Disease

This is part of the Med in Small Doses series, which aims to give you a snapshot of a disease or disorder.

AD movement disorder due to CAG repeats in HD gene. 25-50yo. Commonly presents at age 40.
Dead within 15yrs. Prevalence 5/100 000.

HUNT 4 DATE: HUNTington's on chromosome 4, with cauDATE nucleus involvement.

PATHO: Autosomal dominant HD gene 4p16.3. Toxic gain-of-function on Huntington → protein aggregation → atrophy of caudate nucleus & putamen (striatum). Cortical atrophy, particularly frontal lobe. Ventricular dilatation.

CFs: Motor symptoms before cognitive impairment. Chorea, mental changes/dementia.

Ix: Genetic testing [sensitive (98.8%) & specific (100%)], Imaging Studies (e.g. MRI)

Tx: Symptomatic only: treat chorea (benzodiazepines), bradykinesia (L-dopa/DA Antagonists), delusions, depression (SSRIs). Physiotherapy.