Abstract
Human liver and heart and skeletal muscles contain an enzyme that hydrolyses maltose and glycogen into glucose and which catalyses transglucosylation from maltose to glycogen. This [alpha]-(l[forward arrow] 4)-gluco-sidase is about from the tissues of children affected by Pompe''s disease (cardiomegalic form of glycogen-storage disease). The mechanism by which the absence of maltase can cause glycogen storage is discussed.