Gene Variants of the SLC2A5 Gene Encoding GLUT5, the Major Fructose Transporter, Do Not Contribute to Clinical Presentation of Acquired Fructose Malabsorption.

Abstract

Background: While role of ALDOB-related gene variants for hereditary fructose intolerance is well established, contribution of gene variants for acquired fructose malabsorption (e.g. SLC2A5, GLUT5) is not well understood.Methods: Patients referred to fructose breath test were further selected to identify those having acquired fructose malabsorption. Molecular analysis included (I) exclusion of three main ALDOB gene variants causing hereditary fructose intolerance and (II) sequencing analysis of genomic region comprising of complete coding region, at least 20 bp of adjacent intronic regions and 700 bp of proximal promoter. Results: Thirty-five individuals with acquired fructose malabsorption were identified among 494 patients based on pathological fructose-breath test and normal lactose-breath test. 34 patients (97%) had negative tissue anti-transglutaminase and /or deamidated gliadin antibodies in their medical records. Molecular analysis of SLC2A5/GLUT5 gene of all 35 subjects identified five frequent and five singular gene variants mostly in noncoding regions (promoter and intron). Allele frequencies of gene variants were similar to those reported in public databases strongly implying that none of them was significantly associated with acquired fructose malabsorption. Conclusions: Gene variants of coding exons, adjacent intronic regions and proximal promoter region of SLC2A5 gene are unlikely to contribute to genetic predisposition of acquired fructose malabsorption.