Pathology

Huntington's chorea is characterised by cerebral atrophy with a marked loss of small neurones in the putamen and the caudate nucleus.

There are also changes in neurotransmitters in this disease:

• reduction in enzymes that synthesise GABA and acetylcholine in the striatum
• depletion of neurotransmitters in the substantia nigra, e.g. GABA, ACE and met-enkephalin
• increase in somatostatin levels in the corpus striatum

At the cellular level, degenerating neurones have intranuclear inclusions of aggregated huntingtin protein. It is thought that the glutamine residues coded for by the expanded CAG repeats promote an amyloid-like aggregation of the protein.