Based on the clinical findings in patients with muscular exercise
intolerance exacerbated by glucose infusion prior to exercise, fatigue,
vomiting, muscle weakness, myalgia, cramps, and myoglobinuria.
Phosphofructokinase deficient in skeletal muscle, but not in the liver. No
rise in blood lactate concentration after ischemic exercise. Plasma creatine phosphokinase
is increased. 31P-NMR
spectroscopy reveals a specific peak of phosphorylated monoesters
(accumulation of glycolytic intermediates resulting from the enzymatic
block). A severe infantile form with arthrogryposis, cardiomyopathy, and frequent
respiratory failure has been described. Death occurs early. Antenatal detection
possible in families with identifiable mutations.