Acid maltase deficiency in adults. A study of five cases.

Five adult patients with the myopathic form of acid maltase deficiency are described. In three, the clinical onset dates back from youth with progressive proximal weakness while in the other two, the first symptoms occur after the age of 20 years. Respiratory insufficiency is a direct cause of death in one young adult male and plays an accessory role in the death of an older female patient with an interauricular septal defect. A unilateral diaphragm paralysis is noted in a third patient. A vacuolar myopathy is easily detected in the young adult patients but minimal or moderate lesions are encountered in other muscles or in the older patients. Electron microscopy of muscle and skin biopsies and the assay of acid maltase on muscle completed by the action of antibodies directed against acid maltase represent much more reliable criteria which will confirm the diagnosis. Therefore, when dealing with the heterogeneous group of limb-girdle myopathies, it is necessary to use all adequate diagnostic methods in order to avoid false negative results. The importance of making a correct diagnosis stems from the fact that the respiratory insufficiency should be recognized in order to try to avoid severe complications.