Acid maltase deficiency (type II glycogenosis). Morphological and biochemical study of a childhood phenotype.

Pathological and biochemical data are reported on a 4(4)/12-year-old male patient with a severe myopathic disorder, hepatomegaly, recurrent pulmonary infections ending fatally. Combined morphological and enzymatic studies on muscle biopsy led to the diagnosis of acid maltase deficiency (Type II glycogenosis). On post mortem examination, lysosomal glycogen storage is found in skeletal muscles and liver, while heart and central nervous sytem are spared. Both hydrolytic and transferase activities of acid maltase are absent in cultured fibroblasts, heart, liver and postmortem skeletal muscles. That in the biopsied skeletal muscle only, the transferase activity alone is deficient while the hydrolytic function is maintained at low normal levels correlates well with the abnormal structure of the glycogen stored in that muscle. However, these findings on biopsied muscle cannot be reconciled with the absence of both functions and the presence of normal glycogen in other biopsied tissues or in postmortem specimens from the same patient.