A description of Huntington's disease includes dementia within 1 year of chorea, autosomal dominant inheritance, a CAG repeat expansion, caudate atrophy and decreased GABA. What is the disorder?

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Multiple Choice

A description of Huntington's disease includes dementia within 1 year of chorea, autosomal dominant inheritance, a CAG repeat expansion, caudate atrophy and decreased GABA. What is the disorder?

The features described—chorea with dementia developing within about a year, autosomal dominant inheritance, a CAG repeat expansion, caudate atrophy, and decreased GABA—are classic for Huntington's disease. The CAG expansion in the HTT gene causes a toxic polyglutamine protein that preferentially damages striatal medium spiny neurons, especially those using GABA, leading to reduced GABAergic output and the caudate/putamen degeneration seen on imaging. This degeneration manifests clinically as choreiform movements and progressive cognitive decline, with the autosomal dominant pattern explaining inheritance across generations. Other conditions don’t fit this pattern: Parkinson’s disease centers on nigrostriatal dopaminergic loss with parkinsonian features; Alzheimer's disease shows predominant cortical involvement with memory impairment; PSP presents with vertical gaze palsy and axial rigidity rather than prominent chorea and caudate pathology.

The features described—chorea with dementia developing within about a year, autosomal dominant inheritance, a CAG repeat expansion, caudate atrophy, and decreased GABA—are classic for Huntington's disease. The CAG expansion in the HTT gene causes a toxic polyglutamine protein that preferentially damages striatal medium spiny neurons, especially those using GABA, leading to reduced GABAergic output and the caudate/putamen degeneration seen on imaging. This degeneration manifests clinically as choreiform movements and progressive cognitive decline, with the autosomal dominant pattern explaining inheritance across generations. Other conditions don’t fit this pattern: Parkinson’s disease centers on nigrostriatal dopaminergic loss with parkinsonian features; Alzheimer's disease shows predominant cortical involvement with memory impairment; PSP presents with vertical gaze palsy and axial rigidity rather than prominent chorea and caudate pathology.

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