A 35-year-old man presents with a history of behavioral and personality changes and unusual involuntary movements. Physical examination reveals chorea and dystonia. The patient’s mother and maternal...

A 35-year-old man presents with a history of behavioral and personality changes and unusual involuntary movements. Physical examination reveals chorea and dystonia. The patient’s mother and maternal grandfather had similar clinical symptoms. His mother died in a psychiatric institute, and his maternal grandfather committed suicide. MRI shows bilateral cerebral atrophy and enlargement of the lateral ventricles. Marked atrophy would also be expected in which of the following regions of this patient’s brain?

(A) Anterior horn of the spinal cord

(B) Caudate nuclei

(C) Cerebellum

(D) Hypothalamus

(E) Substantia nigra