[Glycogenosis caused by amylo-1,6-glucosidase deficiency. Myopathy as a lead finding in adults]

Glycogen storage disease due to amylo-1,6-glucosidase deficiency was diagnosed in a 21-year-old patient. The enzyme defect was demonstrated by biochemical analysis of muscle tissue, the glycogen content of which was typically increased. Investigation of the patient's kindred showed that his 25-year-old sister was also affected. This report sets out to show that in adolescence and in adult life myopathy may be the leading symptom of the disease. Besides the clinical symptoms of muscle weakness and stiffness, an increase in serum creatine kinase usually is found. While an increase in the glycogen content of skeletal muscle has been known since the first description of this glycogen storage disease, it was believed that the glycogen deposits do not cause a clinically relevant disturbance of muscle function. A review of the literature and our own observations show that this assumption has to be at least partially revised. In patients with unclear myopathy who had hepatomegaly during childhood the possibility of glycogenosis due to amylo-1,6-glucosidase deficiency should be considered, especially if symptoms of hypoglycemia are reported. In the patient as well as in his sister marked kyphoscoliosis was present. Whether there is a connection between skeletal deformity and enzyme defect cannot be determined as the patients were available for further studies.