Abstract
Congenital sucrase-isomaltase deficiency (CSID) is an autosomal recessive malabsorptive disease of the human small intestine. The absence of SI in patients with this disease results in failure of digestion of dietary sucrose. We have investigated CSID at the protein and cell level in biopsy specimens from 8 patients with this disease. SI was immunoprecipitated from 35S-methionine-labelled organ cultures and from 125I-labelled mucosal homogenates. Further, immunoelectron microscopic visualization of SI by the protein A-gold labelling technique was undertaken. The data accumulated from these studies revealed at least three phenotypes of CSID: one in which sucrase-isomaltase accumulates intracellularly likely in the endoplasmic reticulum, as a high mannose precursor protein (SI-h), one in which the intracellular transport is blocked in the Golgi and finally, one which is transported to the cell surface as catalytically inactive enzyme. All patients expressed SI-h with indistinguisable (6 cases) or slightly elevated apparent molecular weight (2 cases). The data suggest that different mutations in the sucrase-isomaltase gene lead to the synthesis of transport incompetent or enzymatically inactive molecule which results in CSID.
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Naim, H., Sterchi, E., Roth, J. et al. 18 CHARACTERIZATION OF DIFFERENT PHENOTYPES OF CONGENITAL SUCRASE-ISOMALTASE DEFICIENCY (CSID) IN MAN. Pediatr Res 24, 408 (1988). https://doi.org/10.1203/00006450-198809000-00041
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DOI: https://doi.org/10.1203/00006450-198809000-00041