Phosphofructokinase deficiency

Phosphofructokinase deficiency, also known as Glycogen storage disease type VII or Tarui's disease,^[1][2] is metabolic disorder with autosomal recessive inheritance.

It may affect humans as well as other mammals (especially dogs).^[3] In humans it is the least common type of glycogen storage disease. It was named after the Japanese Physician, Seiichiro Tarui (1927- ).

Pathophysiology

In this condition, a deficiency of the M subunit (PFKM) of the phosphofructokinase enzyme impairs the ability of cells such as erythrocytes and rhabdomyocytes (skeletal muscle cells) to use carbohydrates (such as glucose) for energy.

The mutation impairs the ability of phosphofructokinase to phosphorylate fructose-6-phosphate prior to its cleavage into glyceraldehyde-3-phosphate which enters the energy generation phase of glycolysis, effectively limiting energy production.

Unlike most other glycogen storage diseases, it directly affects glycolysis.^[4]

Presentation

The disease presents with exercise-induced muscle cramps and weakness (sometimes rhabdomyolysis), myoglobinuria, as well as with haemolytic anaemia causing dark urine a few hours later. Hyperuricemia is common.^[5] Phosphofructokinase deficiency also presents in a rare infantile form. The infantile form causes severe myopathy and leads to death in infancy or early childhood.

Diagnosis

Other deficiency diseases with similar signs and symptoms include deficiencies of phosphoglycerate kinase, phosphoglycerate mutase, lactate dehydrogenase, beta-enolase and aldolase A.^[5]

A diagnosis can be made through a muscle biopsy that shows excess glycogen and then further tests that will show the levels of phosphofructokinase enzyme.

References

External links

• Glycogen storage disease type 7; Muscle phosphofructokinase deficiency; Tarui disease at NIH's Office of Rare Diseases
• Asociación Española de Enfermos de Glucogenosis