glycogen storage disease V

A glycogen storage disease that is characterized by onset of exercise intolerance and muscle cramps in childhood or adolescence and that has_material_basis_in homozygous or compound heterozygous mutation in the PYGM gene, which encodes muscle glycogen phosphor

A glycogen storage disease that is characterized by onset of exercise intolerance and muscle cramps in childhood or adolescence and that has_material_basis_in homozygous or compound heterozygous mutation in the PYGM gene, which encodes muscle glycogen phosphorylase, on chromosome 11q13.

Signs and symptoms

• Failure to elevate ammonia on ischemic exercise
• Reduced muscle glycogen phosphorylase activity
• Elevated circulating creatine kinase activity
• Rhabdomyolysis
• Failure to elevate lactate upon ischemic exercise test
• Exercise-induced rhabdomyolysis
• Myoglobinuria
• Exercise-induced myalgia
• Dark urine
• Exercise-induced muscle cramps

Also known as: Glycogen storage disease 5; Glycogen storage disease, type V; McArdle's disease; glycogen storage disease type V; myophosphorylase deficiency