What is Duchenne MD?

• A. Autoimmune attack on acetylcholine receptors
• B. Chronic inflammation of joints
• C. Lacking a protein to maintain sarcolemma
• D. Overgrowth of skeletal muscle

Answer: (C)

Duchenne muscular dystrophy happens because the muscle membrane-stabilizing protein dystrophin is missing or nonfunctional. Dystrophin normally links the inside framework of a muscle fiber to the surrounding extracellular matrix, reinforcing the sarcolemma as the muscle contracts. Without dystrophin, the membrane tears more easily during contraction, leading to calcium influx and muscle fiber damage. Over time this causes progressive weakness, especially in proximal muscles, and their calves often appear enlarged due to fat and connective tissue replacing muscle. It’s X-linked recessive and typically starts in early childhood, with progressive loss of ambulation. Treatments can slow progression and manage symptoms, but there’s no cure yet. The other descriptions refer to different conditions—autoimmune attack on acetylcholine receptors is myasthenia gravis; chronic joint inflammation is inflammatory arthritis; and overgrowth of skeletal muscle is not Duchenne.