Phosphofructokinase deficiency associated with congenital nonspherocytic hemolytic anemia and mild myopathy: biochemical and morphological studies on the muscle.

Enzymatic and electron microscopical studies were performed on the muscle of a proband with phosphofructokinase deficiency. Enzymatic studies showed that muscle phosphofructokinase activity of the proband was decreased to about a half of normal. This enzyme was quite thermolabile and had low affinity for fructose 6-phosphate. Electron microscopical studies showed the accumulation of glycogen granules beneath the sarcolemma and between the myofibrils in spite of a lack of accumulation of the intermediates before the step of phosphofructokinase. The proband's clinical symptoms, i.e., hemolytic anemia and myopathy, were considered to be due to the unstable, mutant, muscle-type phosphofructokinase in the red blood cells and muscle.