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PFKM gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

PFKM gene

The PFKM gene provides instructions for a subunit of the phosphofructokinase enzyme, which is essential for breaking down glycogen to provide energy to skeletal muscles.

Normal Function

The PFKM gene provides instructions for making the PFKM subunit of the enzyme phosphofructokinase. This enzyme is crucial for the breakdown of glycogen, a major source of stored energy. In skeletal muscles, phosphofructokinase is composed entirely of subunits produced from the PFKM gene. The enzyme converts fructose-6-phosphate to fructose 1,6-bisphosphate, a key step in providing energy to muscle cells during activity.

Health Conditions Related to Genetic Changes

Glycogen storage disease type VII

At least 20 mutations in the PFKM gene have been found to cause glycogen storage disease type VII (GSDVII). This condition is characterized by an inability to break down glycogen in muscle cells. Symptoms include:

  • Muscle cramps
  • Muscle weakness of varying severity
  • Potential muscle breakdown following moderate strain or exercise

One specific mutation, IVS5+1G>A, accounts for most cases in individuals of Ashkenazi Jewish ancestry. Because the PFKM gene is responsible for the phosphofructokinase enzyme in skeletal muscles, the lack of functional subunits prevents glycogen breakdown in those tissues. In other tissues, different subunits can compensate for the lack of PFKM, which explains why the condition primarily affects muscles.

Genomic Location

The PFKM gene is found on chromosome 12.

Frequently Asked Questions

While no specific diet cures GSD VII, a carbohydrate‑rich diet with frequent small meals can provide a steady glucose supply, reducing reliance on muscle glycogen breakdown. Some patients benefit from a modest increase in simple sugars (e.g., fruit juice) before exercise to boost blood glucose. A balanced intake of protein and healthy fats supports overall muscle health. Consult a metabolic dietitian to tailor carbohydrate timing and quantity to your activity level and to monitor for potential weight gain or blood sugar issues.
GSD VII is inherited in an autosomal recessive pattern, meaning a child must inherit two pathogenic PFKM variants (one from each parent) to be affected. Parents who each carry one copy are typically asymptomatic carriers. Siblings have a 25 % chance of being affected, a 50 % chance of being carriers, and a 25 % chance of having two normal copies. Offer carrier testing to parents and at‑risk relatives, and consider diagnostic enzyme testing or DNA analysis for siblings, especially if they have exercise‑related muscle symptoms.
Elevated CK after exertion is common in GSD VII because the defective phosphofructokinase limits glycolytic ATP production, leading to muscle cell stress. Transient CK rises (often 5‑10 times the upper limit) can occur after unaccustomed or strenuous activity and usually return to baseline within 24‑48 hours. Persistent or markedly high CK (>10‑15 times normal) warrants evaluation for rhabdomyolysis, renal function monitoring, and possible adjustment of the exercise regimen.
Rhabdomyolysis in GSD VII is most often precipitated by moderate‑to‑intense physical activity, especially when the muscles are not conditioned or when dehydration, fasting, or illness is present. To reduce risk, follow a graded exercise program that starts with low‑intensity activities (e.g., walking, gentle cycling) and gradually increases duration and intensity under supervision of a physiotherapist. Stay well‑hydrated, avoid prolonged fasting before workouts, and pause activity if you feel unusual muscle pain, stiffness, or dark urine.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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