glycogen storage disease IXd
Findings
No curated finding names glycogen storage disease IXd yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
A benign form of phosphorylase kinase deficiency caused by variants in PHKA1, characterized by exercise intolerance, myalgia, muscle cramps, myoglobinuria, and progressive muscle weakness.
Definition from the Mondo Disease Ontology (MONDO:0010362), read 2026-09-29. CC BY 4.0.
- Inheritance
- X-linked recessive inheritance
- Onset and course
- Middle age onset
HPO, annotations 2026-09-02
Features
24 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.
- Distal amyotrophyHPOHP:0003693
- 1 of 1 reported patient
- Distal muscle weaknessHPOHP:0002460
- 1 of 1 reported patient
- Glycogen accumulation in muscle fiber lysosomesHPOHP:0030231
- 1 of 1 reported patient
- HypoglycemiaHPOHP:0001943
- 1 of 1 reported patient
- Increased muscle glycogen contentHPOHP:0009051
- 1 of 1 reported patient
- Frequent (30% to 79% of cases)
- Lower limb muscle weaknessHPOHP:0007340
- 1 of 1 reported patient
- Muscle fiber necrosis
Show the remaining 12
- EMG: myopathic abnormalitiesHPOHP:0003458
- Frequent (30% to 79% of cases)
- Exercise intoleranceHPOHP:0003546
- Frequent (30% to 79% of cases)
- FatigueHPOHP:0012378
- Frequent (30% to 79% of cases)
- MyalgiaHPOHP:0003326
- Frequent (30% to 79% of cases)
- CamptocormiaHPOHP:0100595
- Occasional (5% to 29% of cases)
- Difficulty climbing stairsHPOHP:0003551
- 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.
- PHKA1HGNC:8925
- Definitive · ClinGen · X-linked · 2025
- Strong · Genomics England PanelApp · X-linked · 2020
- Strong · Labcorp Genetics (formerly Invitae) · X-linked · 2022
- Strong · PanelApp Australia · X-linked · 2025
- Supportive · Orphanet · Autosomal recessive · 2021
Where it sits
- A kind of
Other names
16 names
Resolves to: glycogen storage disease IXd
- Also called
- glycogen storage disease caused by mutation in PHKA1glycogen storage disease due to muscle phosphorylase kinase deficiencyglycogen storage disease type 9Dglycogen storage disease type IXdglycogenosis due to muscle phosphorylase kinase deficiencyglycogenosis type 9Dglycogenosis type IXdGSD due to muscle phosphorylase kinase deficiencyGSD IXdGSD type 9DGSD type IXdGSD9Dmuscle glycogenosis, X-linked recessivemuscle phosphorylase kinase deficiencyPHKA1 glycogen storage disease