Muscle phosphofructokinase deficiency: two cases with unusual polysaccharide accumulation and immunologically active enzyme protein

Abstract

Two patients with phosphofructokinase (PFK) deficiency had exercise intolerance and increased serum activity of creatine kinase; one presented with hemolytic anemia, hyperuricemia, and gouty arthritis. The glycogen concentration in the muscle of these patients was about twice normal. PFK activity was virtually absent in muscle, but antibodies against the M subunits of the normal human PFK showed cross-reacting material in muscle from both patients. The PFK level in red blood cells, studied in one case, was lower than normal in the patient and both parents. Morphologically, there was extensive deposition of normal glycogen underneath the sarcolemma and in the intermyofibrillar space. In addition, 2% to 3% of the myofibers contained hyaline, PAS-positive, diastase-resistant inclusions that had a filamentous fine structure; histochemical reactions suggested an insoluble form of glycogen. Similar inclusions have not been described previously in PFK deficiency. Accumulation of an abnormal polysaccharide in muscle may be due to a second undiscovered enzymatic defect or may be a metabolic consequence of PFK deficiency.