title: 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.
authors.affiliation: Institute of Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Hannover, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Sander
authors.forename: Marwan
authors.initials: M
authors.lastname: Alfalah
authors.forename: Markus
authors.initials: M
authors.lastname: Keiser
authors.forename: Ilma
authors.initials: I
authors.lastname: Korponay-Szabo
authors.forename: Judit B
authors.initials: JB
authors.lastname: Kovács
authors.forename: Tosso
authors.initials: T
authors.lastname: Leeb
authors.forename: Hassan Y
authors.initials: HY
authors.lastname: Naim
mesh_terms: D001706:Biopsy; D002239:Carbohydrate Metabolism, Inborn Errors / Q000201:enzymology* / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008286:Malabsorption Syndromes / Q000151:congenital* / Q000201:enzymology / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics; D011499:Protein Processing, Post-Translational; D013394:Sucrase-Isomaltase Complex / Q000235:genetics*
chemical_list: D013394:Sucrase-Isomaltase Complex