Metabolic Myopathies

Phosphoglycerate kinase deficiency

What is phosphoglycerate kinase deficiency (glycogenosis type 9)?

Phosphoglycerate kinase deficiency is one of a group of metabolic muscle diseases that interferes with the processing of food (in this case, carbohydrates) for energy production.

What are the symptoms of phosphoglycerate kinase deficiency?

This disease may cause anemia, enlargement of the spleen, mental retardation and epilepsy. More rarely, it causes weakness, exercise intolerance, muscle cramps and episodes of myoglobinuria (acute muscle breakdown leading to rust-colored urine).

What causes phosphoglycerate kinase deficiency?

The condition is caused by a genetic defect in the phosphoglycerate kinase enzyme, which normally breaks down glucose (sugar) for energy production. For more, see Causes/Inheritance.

What is the progression of phosphoglycerate kinase deficiency?

The disease has its onset from infancy to early adulthood, and its muscle symptoms are slowly progressive. As with other metabolic disorders, the earlier the onset, the more severe the symptoms.

What is the status of research on phosphoglycerate kinase deficiency?

Researchers on metabolic diseases of muscle are making progress on a number of fronts, including:

• better diagnosis to allow for earlier identification of at-risk individuals and earlier treatment;
• continued examination of the role of exercise and diet in metabolic diseases;
• development of animal models of metabolic diseases, both to improve understanding of the diseases and to test possible treatments;
• development of enzyme replacement therapies; and
• development of gene therapies.