A 45-year-old man complains that he has been experiencing jerky, uncontrollable movements. He…

A 45-year-old man complains that he has been experiencing jerky, uncontrollable movements. He reports having noticed similar symptoms for the past few years but notes that the symptoms seem to be getting worse. His family history reveals that his father had some of the same symptoms prior to his death in an automobile accident. The magnetic resonance imaging scan shows cell loss in the caudatoputamen. What is the diagnosis?