glycogen storage disease V
Findings
No curated finding names glycogen storage disease V yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Myophosphorylase deficiency (McArdle's disease), or glycogen storage disease type 5 (GSD5), is a severe form of glycogen storage disease characterized by exercise intolerance.
Definition from the Mondo Disease Ontology (MONDO:0009293), read 2026-09-29. CC BY 4.0.
- Inheritance
- Autosomal recessive inheritance
- Onset and course
- Middle age onset · Juvenile onset · Childhood onset
HPO, annotations 2026-09-02
Features
30 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Failure to elevate ammonia on ischemic exerciseHPOHP:6000320
- 3 of 3 reported patients
- Reduced muscle glycogen phosphorylase activityHPOHP:6000358
- 4 of 4 reported patients
- Elevated circulating creatine kinase activityHPOHP:0003236
- 172 of 174 reported patients
- Very frequent (80% to 99% of cases)
- Exercise intoleranceHPOHP:0003546
- Very frequent (80% to 99% of cases)
- Glycogen accumulation in muscle fiber lysosomesHPOHP:0030231
- Very frequent (80% to 99% of cases)
- Highly elevated creatine kinaseHPOHP:0030234
- Very frequent (80% to 99% of cases)
Show the remaining 18
- MyoglobinuriaHPOHP:0002913
- 101 of 202 reported patients
- HyperuricemiaHPOHP:0002149
- 2 of 5 reported patients
- Acute kidney injuryHPOHP:0001919
- Occasional (5% to 29% of cases)
- Exercise-induced muscle stiffnessHPOHP:0008967
- Occasional (5% to 29% of cases)
- Exercise-induced myalgiaHPOHP:0003738
- Occasional (5% to 29% of cases)
- Exertional dyspneaHPOHP:0002875
- Occasional (5% to 29% of cases)
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- PYGMHGNC:9726
- Definitive · ClinGen · Autosomal recessive · 2025
- Definitive · Natera · Autosomal recessive · 2023
- Strong · Genomics England PanelApp · Autosomal recessive · 2020
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2022
- Strong · PanelApp Australia · Autosomal recessive · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
- Limited · Ambry Genetics · Autosomal dominant · 2020
Where it sits
- A kind of
Other names
12 names
Resolves to: glycogen storage disease V
- Also called
- glycogen storage disease caused by mutation in PYGMglycogen storage disease type 5glycogen storage disease type Vglycogenosis due to muscle glycogen phosphorylase deficiencyglycogenosis type 5glycogenosis type VGSD due to muscle glycogen phosphorylase deficiencyGSD type 5GSD type VMcArdle diseasemyophosphorylase deficiencyPYGM glycogen storage disease