Muscle glucose-6-phosphate dehydrogenase deficiency

Abstract

Muscle glucose-6-phosphate dehydrogenase (G6PD) deficiency is described in four clinically heterogeneous patients: an athlete who developed myoglobinuria after physical exercise; a 7-year-old, mildly mentally retarded boy, who had episodes of dark urine and high creatine kinase; and two brothers of Sardinian origin, the elder showing moderate exercise intolerance. Histochemical and biochemical studies showed a lack of G6PD activity in muscle biopsy specimens as well as in erythrocytes. G6PD characterization in erythrocytes classified these mutant enzymes as Mediterranean variant in all the patients. The deficiency was confirmed in the patients' myotubes and skin fibroblasts, where residual activity was present. Electrophoretic studies in tissue culture extracts showed that the residual muscle enzyme migrated as a single electrophoretic band like normal human muscle G6PD.

Stable hybrid myotubes: A new model for studying re-expression of enzymatic activities in vitro

“…The next step was to evaluate G6PD activity in the myotubes obtained from our patients. In confirmation of our previous observations [4] the defect in the Mediterranean variant is expressed in vitro (Fig. 6).…”

“…Our main objective was to use the hybrid model to study the re-expression of a cytoplasmic activity, namely glucose-6-phosphate dehydrogenase (G6PD), a widely distributed X-linked enzyme, in hybrid myotubes formed between G6PD-deficient and G6PD positive myoblasts. Even though anemia is the most frequent clinical manifestation of GtPD deficiency, affecting 400 million people worldwide, a muscular form of this deficiency has been decribed [4]. We thus prepared cell cultures from muscle biopsy specimens of patients affected by the G6PD Mediterranean variant, one of the most common, which has the advantage of expressing the defect in vitro (compared to other variants where the enzymatic activity is not always detectable) and the restoration of GtPD activity in this fusion system was examined in a variety of ways.…”

Glucose 6-phosphate dehydrogenase deficiency in an elite long-distance runner

“…7 The second is a 30-year-old pentathlon-trained athlete with G6PD deficiency who suffered from loss of consciousness and pigmenturia during the last meters of a 12-km competitive run. 8 Contrary to both these reports, our athlete showed no more severe signs of myalgia, myoglobinuria, or hemoglobinuria than other elite long-distance runners, although residual activity in erythrocytes was approximately 9%, and the calculated activity 9 in muscle cells was 13% of normal. We postulate that the athlete described here has developed a unique balance between his G6PD deficiency and exercise-induced disturbances of blood glutathione and lipid peroxidation that allows him to perform strenuous exercise.…”

Bezafibrate-Induced Myopathy: No Evidence for Defects in Muscle Metabolism

“…C K was in the normal range. To exclude the possibility o f a recently described new cause o f acute myopathy with myoglobinuria [11]. we measured glucose-6-phosphate dehydrogenase in red blood cells and it gave a normal result.…”