Novel mutations in the human sucrase-isomaltase gene (SI) that cause congenital carbohydrate malabsorption

Abstract

Disaccharide intolerance I or congenital sucrase-isomaltase deficiency (CSID) is a disorder leading to maldigestion of disaccharides, which is autosomal recessively inherited. Here we analyzed the sucrase-isomaltase (SI) gene from 11 patients of Hungarian origin with congenital sucrase-isomaltase deficiency. Variants in the SI gene had previously been described in CSID patients, which cause amino acid exchanges that affect the transport, the processing, or the function of the SI protein. None of our patients had known mutations for CSID. Our analyses revealed 43 SI variants in total, 15 within exons and one at a splice site. Eight of the exonic mutations lead to amino acid exchanges, causing hypomorph or null alleles. One new variation affects a splice site, which is also predicted to result in a null allele. All potential pathological alterations were present on one allele only. In six out of the 11 patients the phenotype of CSID could be explained by compound heterozygosity.

Quantification of sugars in wheat flours with an HPAEC-PAD method

“…Most publications that analyse these sugars in different cereal matrices with HPAEC-PAD do not study isomaltose (Ammeraal, Delgado, Tenbarge, & Friedman, 1991;Gelders et al, 2003;White, Hudson, & Adamson, 2003), although this is important in human health due to congenital sucrase-isomaltase deficiency (Sander et al, 2005). Isomaltose is naturally present in manuka honey (Weston & Brocklebank, 1999) but also in starch hydrolysis (Ba et al, 2013).…”

Congenital sucrase–isomaltase deficiency: A case report

“…It must be noted that more than 25 mutations have been identified 7 which makes it very difficult in clinical practice to establish a single molecular test suitable for the diagnosis of all CSIDs. 8 Another important discussion point concerns the therapeutic options. Enzyme replacement therapy with sacrosidase (Sucraid ® ) facilitates breakdown of sucrose into simpler forms for absorption.…”

Congenital sucrase–isomaltase deficiency: identification of a common Inuit founder mutation

“…Nonetheless, reports of gastrointestinal symptoms in small numbers of people with only a single identifiable SI mutation do raise the question of whether carriers may have mild symptoms when exposed to sucrose. 17,23 The availability of a noninvasive (molecular) test for congenital sucrase-isomaltase deficiency raises the possibility of a more systematic study of the phenotype, if any, in heterozygous people.…”