In polysaccharide storage myopathy (PSSM), how does insulin influence disease progression?

In polysaccharide storage myopathy (PSSM), how does insulin influence disease progression?

• A. Promotes glycogen synthesis
• B. Inhibits glycogen breakdown
• C. Increases lipolysis
• D. Decreases glucose uptake

Answer: (A)

Insulin promotes glycogen synthesis in skeletal muscle, which directly drives the storage of the abnormal glycogen-like material seen in PSSM. When insulin signals, glucose is taken up into muscle cells and glycogen synthase is activated to add glucose units to glycogen. In PSSM, this increased synthesis adds to the storage burden in muscle fibers, worsening stiffness, cramps, and exercise intolerance. While insulin also inhibits glycogen breakdown and increases glucose uptake, the central factor for disease progression is the boost in glycogen synthesis and substrate availability for storage.

Insulin promotes glycogen synthesis in skeletal muscle, which directly drives the storage of the abnormal glycogen-like material seen in PSSM. When insulin signals, glucose is taken up into muscle cells and glycogen synthase is activated to add glucose units to glycogen. In PSSM, this increased synthesis adds to the storage burden in muscle fibers, worsening stiffness, cramps, and exercise intolerance. While insulin also inhibits glycogen breakdown and increases glucose uptake, the central factor for disease progression is the boost in glycogen synthesis and substrate availability for storage.