Maltase‐Glucoamylase and Residual Isomaltase in Sucrose Intolerant Patients

Abstract

Summary: Small intestinal biopsies from nine patients with sucrase‐isomaltase deficiency (sucrose‐intolerance) were analyzed. All patients lacked sucrase activity and three patients had a residual isomaltase activity and a corresponding isomaltase precipitate following immunoelectrophoresis. By polyacrylamide gel electrophoresis in sodium dodecyl sulfate followed by immunoblotting the residual isomaltase appeared as a single polypeptide with molecular weight of ∼145,000. Maltase‐glucoamylase in the biopsies was specifically quantitated by crossed immunoelectrophoresis. One of the patients had an almost total deficiency of maltase‐glucoamylase in the biopsy, three patients had a normal amount of maltase‐glucoamylase, and five patients constituted an intermediary group. These results indicate that some of the sucrase‐isomaltase deficient patients also have a more or less pronounced deficiency of maltase‐glucoamylase. The patients constitute an even more heterogeneous group than earlier suggested and should be classified by the amount not only of sucrase and isomaltase but also of maltase‐ glucoamylase.