Which parts of the nervous system are affected by Huntington disease?

Huntington disease primarily affects the basal ganglia, a pair of nerve clusters located deep within the brain that are responsible for controlling movement. Specifically, the pathology involves the degeneration and death of a population of projection neurons within the striatum—a component of the basal ganglia that includes the caudate nucleus and the putamen.123

Additionally, the disease is associated with the loss of neurons and the subsequent thinning of the cerebral cortex, which contributes to the progressive decline in cognitive ability and behavioral changes observed in patients. These neurological changes are driven by a genetic mutation in the HTT gene, which leads to the accumulation of abnormal huntingtin proteins that cause neuronal dysfunction.451