This mutation is

It is

Huntington disease is caused by a genetic defect on chromosome 4. The defect causes a part of DNA, called a CAG repeat, to occur many more times than it is supposed to.

Chromosomal

Insertion

The abnormal protein increases the level of the p53 protein in brain cells causing their death by apoptosis.

The human brain, showing the impact of HD on brain structure in the basal ganglia region of a person with HD (top) and a normal brain(bottom).

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