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Bitterness of Glucose/Galactose: Novel Mutations in the SLC5A1 Gene

Pode-Shakked, Ben*; Reish, Orit; Aktuglu-Zeybek, Cigdem; Kesselman, Dafna§; Dekel, Benjamin||; Bujanover, Yoram; Anikster, Yair*

Journal of Pediatric Gastroenterology & Nutrition: January 2014 - Volume 58 - Issue 1 - p 57–60
doi: 10.1097/MPG.0000000000000114
Original Articles: Gastroenterology

ABSTRACT: Glucose galactose malabsorption (GGM) is a rare autosomal recessive disorder characterized by life-threatening osmotic diarrhea at infancy. When the intake of the offending sugars (namely, glucose, galactose and lactose) is ceased, the diarrhea promptly stops. Mutations in the SLC5A1 gene, encoding the sodium-glucose co-transporter located in the brush border of enterocytes, have been shown to cause the disease. More than 300 subjects of diverse origin have been reported worldwide, most of whom are a result of a consanguineous union. We examined 6 patients from 4 families presenting with complaints consistent with GGM and responsive to the appropriate fructose-based diet. Genomic DNA of the patients was polymerase chain reaction amplified for each of the 15 exons of the SLC5A1 gene and analyzed by nucleotide sequencing. The analysis lead to the identification of 2 novel mutations: a 1915 del C mutation, a frameshift mutation leading to a premature stop at codon 645; and a substitution missense mutation of T to C on nucleotide 947 (exon 9) causing a L316P substitution. In addition, G426R and C255W mutations previously described were identified; in both cases, the patients were shown to be homozygous and their parents heterozygous for the mutation. Of note, additional patients who underwent a similar evaluation at our center for suspected GGM did not show mutations in the SLC5A1 gene. Because the latter did not previously undergo a diagnostic algorithm in full, for instance, one that may consist of a glucose breath hydrogen test and an empiric attempt of a dietary switch to galactomin, we suggest that molecular genotyping of such patients should only follow such appropriate clinical evaluation.

*Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer

Genetics Institute, Assaf Harofeh Medical Center, Zerifin, Israel

University of Istanbul, Cerrahpasa Medical Faculty, Department of Pediatrics, Division of Metabolic Diseases, Istanbul, Turkey

§Department of Biological Resources Engineering, University of Maryland, College Park

||Pediatric Stem Cell Research Institute, Edmond & Lily Safra Children's Hospital, Sheba Medical Center

Pediatric Gastroenterology and Nutrition Unit, Edmond and Lily Safra Children's Hospital.

Address correspondence and reprint requests to Yair Anikster, MD, PhD, Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, 52621, Israel (e-mail: yair.anikster@sheba.health.gov.il).

Received 12 July, 2013

Accepted 9 August, 2013

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The authors report no conflicts of interest.

© 2014 by European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology,