Its autosomal dominant disorder characterized pathologically by degeneration of GABA-nergic neurons of caudate nucleus and clinically by chorea and dementia.
Clinical presentation
- Involuntary writhing motions (i.e., choreiform) when pre-senting in adults during the fourth or fifth decades; seizures
- and rigidity when presenting at a younger age.
- Depression and cognitive impairment (i.e., dementia).
- Patients often commit suicide because of the prognosis.
- Huntingtin gene on chromosome 4.
- Mutation is an increase in the number of CAG repeats in the huntingtin gene.
- Transcription of the expanded CAG repeats results in the accumulation of excess numbers of polygluta-mine residues in the huntingtin protein.
- There is an inverse relationship between the number of CAG repeats and the age of onset of disease.
- The CAG repeats increase in number during spermatogenesis,which results in the disease presenting earlier in successive generations (referred to as anticipa-tion)
Clinical manifestation
i. The disease manifests between age 20-40 years.
ii.Chorea:sudden,unexpected and purposeless contractions of proximal muscles
iii. Changes in personality,marked tendency for suicide and dementia
Microscopic findings
Loss of medium spiny GABA-nergic neurons in the caudate and putamen,associated with gliosis
Diagnosis:
Genetic diagnosis possible but controversial
Treatment:
Antipsychotic drugs (e.g; haloperidol)
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