system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 38-year-old man comes to the physician because of a 6-month history of chest discomfort and progressive dyspnea. He cannot do daily chores without feeling out of breath. He has a history of an X-linked recessive disorder that causes progressive proximal muscle weakness and gait abnormalities. Physical examination shows a waddling gait and weak patellar reflexes. Cardiovascular examination shows a holosystolic murmur, displaced point of maximal impulse, and bilateral pitting edema of the ankle. Laboratory studies show elevated levels of brain natriuretic peptide. Which of the following is the most likely underlying cause of this patient's muscle weakness?
assistant
Impaired connection of cytoskeletal actin filaments to membrane-bound dystroglycan