Problem: An 8-year-old boy is brought to the office by his parents due to involuntary movement of his arms and legs for the past 5 days. The movement is described as irregular, unpredictable, and dance-like in character. His parents also report mild but coherent slurred speech and occasional intermittent throat clearing. His vaccinations are up-to-date, and his medical history is unremarkable. However, his mother recalls that he had a fever and sore throat about 8 weeks ago that resolved after 1 week of symptomatic therapy. On physical examination, the boy demonstrates rapid, irregular movements involving his upper extremities more than his lower extremities. He tries to incorporate the irregular movements with his regular movements. Mild gait impairment due to the involvement of both legs is also noted. If he is not treated appropriately, this patient is most at risk for developing which of the following conditions? Looking for Assignment Help? A. Mitral valve disease B. Early-onset dementia C. Juvenile rheumatoid arthritis D. Huntington disease