Your answers must be in the discussion board, (not in an attachment), to facilit

Your answers must be in the discussion board, (not in an attachment), to facilitate class discussion. If the answers are not in the discussion board post the grade will be a zero. Please provide citations when answering the following case studies. At least 2 references are present (text, outside scholarly source less than 5 years old). See the attached rubric.
A 63-year-old man comes to the clinic with a several-month history of difficulty with his gait and coordination. He finds walking difficult and has almost fallen on a number of occasions, especially when trying to change directions. He has also found that using his hands is difficult, and other people have noticed that his hands shake. Physical examination is notable for a resting tremor in the hands that disappears with intentional movement. He has a shuffling gait with difficulty turning. There is so-called cogwheeling rigidity in his arms, a jerky sensation with passive flexion and extension of the arms.
What is the likely diagnosis? What clinical features make this diagnosis likely?
What are the underlying pathologic changes responsible for the clinical presentation?
What are some possible molecular mechanisms responsible for the pathologic changes?