[Cardiac-muscle Lysosomal Glycogenosis in Adults Without Known Enzyme Deficiency - a Cause of Familial Myocardiopathy and Lysosomal Glycogen Overload With Normal Acid Maltase Level]

: An unusual form of familial myocardiopathy is reported. The disease affected siblings entering adulthood and presented as subclinical skeletal muscle and patent cardiac muscle lesions. Quadriceps muscle biopsy performed in a young man who subsequently died of cardial failure revealed excessive lysosomal glycogen storage, as in type II glycogenosis, but biochemistry showed normal enzymatic activity. In a sister with hypertrophic myocardiopathy only leucocytes were examined; they also showed normal enzymatic activity. Other clinical manifestations of this form of familial myocardiopathy are hypoglycaemia and moderate skeletal muscle involvement. At histology, the image is that of Pompe's disease, but the acid maltase level is normal. The condition seems to be transmitted as an autosomal dominant trait.