Myophosphorylase deficiency (glycogenosis type V; McArdle disease)

Curr Mol Med. 2002 Mar;2(2):189-96. doi: 10.2174/1566524024605770.


McArdle disease, one of the most common metabolic causes of exercise intolerance and recurrent myoglobinuria, is due to biochemical defects of the muscle isoform of glycogen phosphorylase. The gene for myophosphorylase (PGYM) is on chromosome 11, and 33 distinct mutations have been identified in patients from all over the world. In Caucasians, a nonsense mutation in exon 1 (R49X) is common enough to warrant screening of genomic DNA from blood before considering muscle biopsy. Other mutations are prevalent in different ethnic groups or are "private". Mutations are spread throughout the gene and there is no clear genotype:phenotype correlation. High-protein diet and aerobic exercise are beneficial, and gene therapy appears promising.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adolescent
  • Animals
  • Codon, Nonsense
  • Disease Models, Animal
  • Exons
  • Female
  • Genetic Therapy
  • Genotype
  • Glycogen Phosphorylase, Muscle Form / chemistry
  • Glycogen Phosphorylase, Muscle Form / genetics
  • Glycogen Storage Disease Type IV / diagnosis*
  • Glycogen Storage Disease Type IV / genetics*
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Models, Genetic
  • Mutation
  • Phenotype
  • Protein Isoforms


  • Codon, Nonsense
  • Protein Isoforms
  • Glycogen Phosphorylase, Muscle Form