GLYCOGENOSIS type 2 (Pompe's disease) has been recognized as a clinical entity since 1933.1 Characteristically, it presents early in infancy with failure to thrive and cardiomegaly.2 This may be associated with a generalized hypotonia. In some instances, the muscular hypotonia may be the predominant symptom and may be so extreme as to suggest amyotonia congenita.3 In 1963, Hers4 reported an absence of the lysosomal enzyme, acid maltase (α-1,4-glucosidase) in the tissues of patients with Pompe's disease and suggested that this is the fundamental biochemical defect leading to the accumulation of glycogen.
Fibroblasts were grown from the skin of a patient with Pompe's disease and tested for the presence of acid maltase activity using a sensitive assay method. Although such activity could be easily demonstrated in normal skin fibroblasts, none could be detected in those derived from the patient. This confirms a similar observation made on another