Muscular form of glycogenosis type II (Pompe's disease).

An 11-year-old boy who was previously thought to have progressive muscular dystrophy was studied clinically, biochemically, and histologically. He was seen initially with an amyotonic syndrome with no clinical evidence of heart disease. Light and histochemical examination showed vacuolar degeneration and abnormal accumulation of glycogen in the muscular fibers. Electron microscopy showed aggregates of glycogen granules surrounded by a well-defined membrane, as in previously reported cases of type II glycogenosis. Enzymatic study disclosed that acid alpha-glucosidase was deficient in muscle, liver, and heart tissue, although neutral alpha-glucosidase was present within normal ranges. Measurement of acid and neutral alpha-glucosidase activity in muscle from the patient and his sisters and in urine from them and their parents indicated that his sisters are heterozygotes and his parents probably are heterozygotes. The disease was transmitted as an autosomal-recessive trait.