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glycogen storage disease type-V (McArdle type glycogen storage disease)

Genetics: - associated with defects in PYGM Clinical manifestations: - pain & stiffness after exertion - exercise intolerance, muscle cramps, muscle weakness - carbohydrate-rich diet improves exercise tolerance - '2nd wind' phenomenon: a brief break after onset of symptoms allows for improved exercise tolerance [2] Laboratory: - myoglobinuria in 50% - renal insufficiency - PYGM gene mutation Special laboratory: - normal response of plasma glucose to IM glucagon

Related

phosphorylase-M (myophosphorylase, muscle glycogen phosphorylase, PYGM)

General

glycogen storage disease (glycogenosis) metabolic myopathy

Properties

DEFICIENT-PROTEIN: phosphorylase-M CONFIGURATION: dimer COMPARTMENT: cytoplasm MOTIF: Ser phosphorylation site {S15} binding site SITE: 76-76 FOR-BINDING-OF: AMP cysteine residue {109} cysteine residue {143} tyrosine residue {156} Tyr phosphorylation site {Y473} cofactor-binding site [681-681] FOR-BINDING-OF: pyridoxal phosphate

Database Correlations

OMIM 232600

References

  1. Clinical Diagnosis & Management by Laboratory Methods, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1991, pg 185
  2. Medical Knowledge Self Assessment Program (MKSAP) 18, American College of Physicians, Philadelphia 2018