Also known as muscle phosphofructokinase deficiency or Tarui disease.
The clinical features of Type VII are similar to those of Type V with onset of more severe fatigue and muscle pain early in exercise. Symptoms are evident in childhood. Type VII is caused by a deficiency of the phosphofructokinase enzyme which is needed to facilitate the breakdown of glucose into energy in muscle during exercise.
The body breaks down muscle (rhabdomyolysis) when trying to attain energy, which causes symptoms such as muscle pain, cramping, fatigue and tenderness. The red protein myoglobin is released and red-brown urine may be seen.
Diagnosis is by muscle biopsy, which will show a deficiency of muscle phosphofructokinase and a modest accumulation of glycogen. Patients may also display a hemolytic anemia. Treatment primarily consists of avoiding strenuous exercise. Some patients have been helped by a high protein diet. The enzyme deficiency is due to abnormalities in the muscle phosphofructokinase gene and is inherited as an autosomal recessive genetic disorder.
The Coordinator for Type VII is Marilyn Silver, who has the condition herself. (This is a voluntary unpaid role.) You can contact her via the Contact us page.
Association for Glycogen Storage Disease (UK) LimitedRegistered Charity No 1132271