Marie is a 32-year-old mother of three complaining of fatigue and muscle cramps

Question

Marie is a 32-year-old mother of three complaining of fatigue and muscle cramps with exercise. She had always blamed her intolerance to exercise on her sedentary lifestyle. However, she recently joined a gym and after a week of aerobics classes went to her physician, who ordered a series of blood tests. The blood work came back with abnormal results, leading to her muscle biopsy and referral to the metabolic clinic.

The muscle biopsy showed an excess of glycogen. How can a deficiency of phosphofructose kinase lead to an increase in glycogen? Why would other tissues not be affected?

Explanation / Answer

Question: The muscle biopsy showed an excess of glycogen. How can a deficiency of Phosphofructose kinase lead to an increase in glycogen? Why would other tissues not be affected?

Answer: Phosphofructokinase (PFK) deficiency is a glycogen storage disorder (GSD). This is genetic disorder and inherited but rare in infection. The reason behind the disorder is mutation in the gene encoding for muscle phosphofructose-1-kinase enzyme – a key enzyme play role in glycolysis process. The deficiency of enzyme in muscle causing reduction of red cell activity. People deficient in Phosphofructokinase faces muscle cramping, exertional myopathy, compensated haemolysis and myoglobinuria etc. due to lack of PFK activity blocking the glycolysis process resulting the accumulation of glycogen in muscles and low ATP. Also there will be increase production of uric acid and possibility of Gout.

The deficiency of Phosphofructose-1-kinase enzyme leads to the malfunction of all the muscles require continues ATP (energy) to perform their action as Heart muscles, skeletal muscles, Respiratory muscles will be impacted.

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