A 42-year-old man is being followed up for worsening involuntary jerky movements. During the course of his disease, he develops depression and progressive dementia. Within several years he dies, and during an autopsy, bilateral atrophy of the caudate nuclei is found. What is the basic abnormality involved in this individual's disease process

Bilateral atrophy of the caudate nuclei is characteristic of Huntington disease, an inherited autosomal dominant disease that is characterized by the combination of choreiform movements, depression, and progressive dementia. This disorder results from increased numbers of trinucleotide repeats within the HD gene. Thus, this disorder is an example of a triple repeat mutation disorder, other examples of which include fragile X syndrome and myotonic dystrophy. Ref:- Harsha Mohan textbook of Pathology