title: Congenital sucrase-isomaltase deficiency: identification of a common Inuit founder mutation.
abstract: BACKGROUND
  Congenital sucrase-isomaltase deficiency is a rare hereditary cause of chronic diarrhea in children. People with this condition lack the intestinal brush-border enzyme required for digestion of di- and oligosaccharides, including sucrose and isomaltose, leading to malabsorption. Although the condition is known to be highly prevalent (about 5%-10%) in several Inuit populations, the genetic basis for this has not been described. We sought to identify a common mutation for congenital sucrase-isomaltase deficiency in the Inuit population.
  
  
  METHODS
  We sequenced the sucrase-isomaltase gene, SI, in a single Inuit proband with congenital sucrase-isomaltase deficiency who had severe fermentative diarrhea and failure to thrive. We then genotyped a further 128 anonymized Inuit controls from a variety of locales in the Canadian Arctic to assess for a possible founder effect.
  
  
  RESULTS
  In the proband, we identified a novel, homozygous frameshift mutation, c.273_274delAG (p.Gly92Leufs*8), predicted to result in complete absence of a functional protein product. This change was very common among the Inuit controls, with an observed allele frequency of 17.2% (95% confidence interval [CI] 12.6%-21.8%). The predicted Hardy-Weinberg prevalence of congenital sucrase-isomaltase deficiency in Inuit people, based on this single founder allele, is 3.0% (95% CI 1.4%-4.5%), which is comparable with previous estimates.
  
  
  CONCLUSIONS
  We found a common mutation, SI c.273_274delAG, to be responsible for the high prevalence of congenital sucrase-isomaltase deficiency among Inuit people. Targeted mutation testing for this allele should afford a simple and minimally invasive means of diagnosing this condition in Inuit patients with chronic diarrhea.
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont.
authors.forename: Julien L
authors.initials: JL
authors.lastname: Marcadier
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont.
authors.forename: Margaret
authors.initials: M
authors.lastname: Boland
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont.
authors.forename: C Ronald
authors.initials: CR
authors.lastname: Scott
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont.
authors.forename: Kheirie
authors.initials: K
authors.lastname: Issa
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont.
authors.forename: Zaining
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont.
authors.forename: Adam D
authors.initials: AD
authors.lastname: McIntyre
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hegele
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Geraghty
authors.affiliation: Department of Genetics (Marcadier), Children's Hospital of Eastern Ontario; Division of Gastroenterology, Hepatology and Nutrition (Boland), Children's Hospital of Eastern Ontario; Department of Pediatrics (Boland, Issa, Geraghty, Lines), University of Ottawa and Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ont.; Department of Pediatrics (Scott, Wu), University of Washington, Seattle, Wash.; Robarts Research Institute (McIntyre, Hegele), Schulich School of Medicine and Dentistry, Western University, London, Ont.; Metabolics (Geraghty, Lines), Children's Hospital of Eastern Ontario, Ottawa, Ont. mlines@cheo.on.ca.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Lines
mesh_terms: D002170:Canada / Q000453:epidemiology; D002239:Carbohydrate Metabolism, Inborn Errors / Q000175:diagnosis / Q000208:ethnology* / Q000235:genetics*; D016022:Case-Control Studies; D004252:DNA Mutational Analysis; D005260:Female; D018703:Founder Effect; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D004930:Inuit / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D013394:Sucrase-Isomaltase Complex / Q000172:deficiency* / Q000235:genetics*
chemical_list: D013394:Sucrase-Isomaltase Complex