Huntington's Chorea (Huntington's
Please read our disclaimer
- Huntington's chorea is a dominantly inherited disease typified by choreoathetosis,
rigidity, dementia, ataxia, and ophthalmoplegia.It was first described by
George Huntington in 1872. Incidence is 5-10/100,000.
- Genetically, it is an autosomal dominant disorder with complete penetrance.
The mutation, CAG-trinucleotide repeats, may expand in descendent generations
- Onset occurs from childhood (10% of cases) into late life, but is usually
in the mid-30s to mid-40s. Progression is relentless usually ending
in death within 10-20 years. The CAG repeats encode glutamines in the gene
for "huntington". However the contribution of the mutant form of
huntington is presently unclear.
- Gene imprinting explains the transmission of the childhood form primarily
through the father. The disease often presents as "nervousness",
and depression. Eventually progresses to include dementia and slowed eye movements.
In juvenile HD, rigidity and parkinsonian tremor may be the primary manifestation.
- HD is a basal ganglia disease; the portions most severely affected are caudate
and putamen. The most significant neuropathological change is a preferential
loss of medium spiny neurons in the neostriatum. Biochemically there is marked
loss of GABA, substance P, enkephalin, angiotension converting enzyme. Neuronal
changes begin very early in life, perhaps even from birth. There is no known
treatment that will stop progression, but there are symptomatic treatments
such as haloperidol. Huntingtons can be diagnosed on MRI by caudate atrophy
with appropriate history, and also by genetic testing.
- Differential diagnosis includes hepatocerebral degeneration, schizophrenia
with tardive dyskinesia, other chorea's, and drug reactions.
- Penny JB and Young AB, Huntingtons Disease IN Parkinsons Disease
and Movement Disorders (eds. Jankovic and Tolosa), 1993, Williams & Wilkins).
- Sapp et al. Huntingtin localization in brains of normal and huntington's
disease patients. Ann Neurol 1997:42:604-12