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Snapshot
  • A 20-year-old man presents with a two-year history of motor restlessness that has progressed to uncontrollable choreiform movements. He has moderate dementia with a severe gait disturbance as well as agitation and problems with his mood. MRI scan of the brain shows atrophy of the cerebral cortex and caudate nucleus.
Introduction
  • An autosomal dominant disorder characterized by
    • choreiform movements
    • progressive intellectual deterioration
    • exhibits genetic anticipation
  • Epidemiology
    • demographics
      • symptoms usually begin to appear in the 3rd-5th decade of life
      • both sexes are affected equally
    • incidence
      • 0.38 cases per 100,000 per year
  • Genetic 
    • inheritance
      • autosomal dominant
    • mutation
      • CAG triplet repeat expansion in huntingtin gene (chromosome 4
        • HUNT 4 an animal, put it in a CAGe
      • demonstrates anticipation
      • mutation leads to atrophy of striatum (especially caudate nucleus) with neuronal loss and gliosis 
      • decrease in the levels of GABA and ACh 
  • Pathophysiology
    • changes in neurotransmitters with Huntington's disease
      • ↑ dopamine and ↓ GABA and ACh
        • high dopamine can act on the nigro-striatal pathway to result in hyperkinesis
        • high dopamine can act on the meso-limbic pathway to result in psychotic symptoms
Presentation
  • Symptoms
    • progressive choreiform movements of all limbs
    • ataxic gait
    • dementia
    • depression
    • grimacing
Evaluation
  • MRI
    • shows atrophy of caudate
Treatment
  • Pharmacologic
    • no known cure
    • medications used to treat Huntington's disease include 
      • amine-depleting agents (inhibit VMAT, involved in monoamine transport)
        • reserpine
          • ↓ release of amines (dopamine)
        • tetrabenazine
          • ↑ degradation of amines (dopamine)
      • antipsychotics
        • haloperidol
          • dopamine receptor antagonist
          • ↓ effect of excess dopamine resulting in psychotic symptoms
          • antipsychotics
      • muscle relaxants
        • benzodiazepines
Prognosis, Prevention, and Complications
  • Death inevitable
  • Suicide common cause of death
 

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