Acid maltase deficiency in adults. Clinical, morphological and biochemical study of three patients.

3 adult women with distinct clinical pictures of progressive myopathy were studied. The morphological findings of biopsied skeletal muscle suggested the diagnosis of type II glycogenosis. Biochemical analysis confirmed a profound deficiency of alpha-1,4-glucosidase activity. Electrophoresis of muscle acid maltase showed the presence of one band in normal individuals. A very faint band with normal electrophoretic mobility was present in the patients' muscles. Muscle neutral maltase is composed of four bands in normal adult individuals: two of the four bands were clearly reduced in the muscles of the patients. The acid and neutral maltases were not significantly reduced in the patients' leukocytes. Acid maltase determination in urine made it possible to identify the homozygous, but not to completely segregate the heterozygous, from unaffected adult subjects.