[Biochemical analysis using biopsied muscle in 72 patients with metabolic myopathies]

Biochemical analysis using biopsied muscle specimens was performed on 72 cases who had symptoms suggesting metabolic myopathies. Sixteen out of 72 cases (22%) were diagnosed as having chemically confirmed metabolic defects. Of these 16 cases, 9 had defects in the glycolytic pathway (glycogen storage disease type II; 3 cases, type III; 1 case, type V; 3 cases, phosphoglycerate kinase deficiency; 1 case, phosphoglucomutase deficiency; 1 case) and 7 cases in mitochondrial metabolism (complex IV deficiency; 4 cases, carnitine deficiency; 3 cases). Among 14 cases who were strongly suspected as having a defect in the glycolytic pathway because of abnormal ischemic forearm test, 6 (43%) showed biochemically proved glycolytic defects. These data suggest that care should be taken when evaluating the results of ischemic forearm test. In addition, we should carefully interpret the muscle histochemistry, because histochemical stains including PAS might be fairly normal in the defects with second step glycolytic pathway.