Myopathy due to glycogen storage disease: pathological and biochemical studies in relation to glycogenosome formation.

Ten cases of myopathy caused by glycogen storage diseases of type II, III, and V, and phosphorylase b kinase deficiency are reported. So-called "abnormal lysosomes" or glycogenosomes which contain abundant glycogen were found in cases of type II, and in some numbers, in cases of type III, and in one case of phosphorylase b kinase deficiency which revealed a moderate decrease in debranching enzyme (amylo-1,6-glucosidase) activity. In these cases of type III and phosphorylase b kinase deficiency, the glycogenosomes are formed through deposition of abnormal glycogen (limit dextrin structure glycogen).