Medical Genetics

Huntington's disease

An autosomal-dominant neurodegenerative disorder caused by a CAG-repeat expansion in HTT, producing progressive motor, cognitive and psychiatric change; diagnosis and predictive testing require specialist genetics support and treatment is symptomatic and multidisciplinary.

Definition

Huntington's disease is a progressive autosomal-dominant neurodegenerative disorder caused by an expanded CAG trinucleotide repeat in the HTT gene. It produces a changing combination of movement, cognitive, psychiatric and functional impairment.

First principles

One expanded HTT allele is sufficient

Huntington's disease is caused by an expanded CAG repeat in the HTT gene on chromosome 4. The repeat encodes an abnormally long polyglutamine tract and the altered huntingtin protein progressively damages vulnerable neurons, especially in the striatum.

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