Huntington’s disease

Huntington’s disease, named after George Huntington, is an autosomal dominant disease caused by a loss of GABAergic neurons of the basal ganglia, especially of the caudate nucleus and putamen.
The mutation responsible is on Chromosome 4p16:3, and consists of a CAG trineucleotide repeat.
Presention is in the 30s to 50s, with equal M:F ratio, and is characterised by the development of dementia, choreoathetosis and psychosis. In approximately 5 - 10% symptoms occur before the age of 20. This is the so called ‘juvenile’ form, and has a worse prognosis. Typically these patients had an affected father (why?).
Adult onset inevitably lead to death in 15 - 20 years, and the juvenile form in 7 - 8 years.
Radiologically the heads of caudate are atrophied with enlargement of the frontal horns, along with a more generalised cortical atrophy. MRS demonstrates elevation of lactate in the occipital cortex, which correlates with duration of symptoms.
Reference: Osborn A. Diagnostic Imaging: Brain Amirsys 2004
Credit: Dr Frank Gaillard
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