Acid maltase deficiency in adults: studies in four cases of a syndrome which may mimic muscular dystrophy or other myopathies

Acid maltase deficiency in adults: studies in four cases of a syndrome which may mimic muscular dystrophy or other myopathies

IN 1959 Sant'Agnese suggested that marked cardiac enlargement, generalized glycogen storage, normal glycogen structure, normal glycogenolysis in liver and muscle, and death in infancy were the diagnostic criteria of "cardiomegalia glycogenica," the disease described by Pompe in 1932. Since then, as a consequence of Hers' discovery of acid maltase deficiency (AMD) in infantile cases of the disease (Hers, 1963), the clinical concept of type 2 glycogenosis has gradually undergone a revision. In milder cases, with little cardiac damage, the patients were found to survive beyond the age of 2 years or even into the second decade of life (cases cited in Discussion). This study shows that AMD can also present as a syndrome of muscular weakness in adults. In the past four years, 4 such patients were studied at the Mayo Clinic. The clinical diagnosis was muscular dystrophy in 2 of these cases and muscular dystrophy or possibly polymyositis in the other 2. Morphological and preliminary biochemical observations in the first case were reported in 1968 by Engel and Dale. In the other cases, as in the first, a vacuolar myopathy and an excess of periodic acid-Schiff (PAS) reactive material in the vacuoles suggested a storage disease while electron microscopy demonstrated extensive sequestration of glycogen in membrane-bound sacs. The morphological findings prompted biochemical investigations which showed an excess of muscle glycogen and AMD in all 4 cases. Another case of AMD presenting with weakness in adult life was reported by Hudgson et al. in 1968.