Acid maltase deficiency is a generalized enzyme defect that blocks lysosomal degradation of glycogen but does not affect the energy-yielding process of glycogenolysis. A fatal infantile form of the disease (Pompe's disease) is associated with hypotonia and cardiopulmonary failure. Childhood and adult forms of the enzyme deficiency are characterized by progressive myopathy in which there is often early impairment of respiration, owing to involvement of the diaphragm. The childhood disorder may mimic muscular dystrophy, and the adult form may resemble myositis or limb girdle dystrophy. A high-protein diet - 20 to 30 percent of daily calorie intake (2 to 2.5 g per kilogram per day for adults; 4 to 5 g per kilogram per day for children) - combined with regular exercise has been reported to be of benefit. Regular pulmonary function testing with institution of ventilatory support when necessary is an important component of managing the disease.