USMLE Step 1

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Biochemistry

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Autosomal Dominant Diseases

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Huntington Disease

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Huntington Disease is an autosomal dominant disorder characterized by choreiform movements and progressive dementia.

The disease is caused by a CAG trinucleotide repeat affecting the huntingtin gene on chromosome 4. Patients affected typically have choreiform movements (dance-like), progressive dementia, and aggressive behavior. Depression is commonly observed and should be actively managed. Neurotransmitter levels in the brain show elevated dopamine levels, and reduced GABA and acetylcholine.

Imaging of the brain will show caudate atrophy, creating the appearance of larger ventricles (hydrocephalus ex vacuo).

Find Huntington Disease and other Autosomal Dominant Diseases among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.