Hypomorphic SI genetic variants are associated with childhood chronic loose stools

Bruno P. Chumpitazi, Jeffery Lewis, Derick Cooper, Mauro D'Amato, Joel Lim, Sandeep Gupta, Adrian Miranda, Natalie Terry, Devendra Mehta, Ann Scheimann, Molly O'Gorman, Neelesh Tipnis, Yinka Davies, Joel Friedlander, Heather Smith, Jaya Punati, Julie Khlevner, Mala Setty, Carlo Di Lorenzo

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Objective The SI gene encodes the sucrase-isomaltase enzyme, a disaccharidase expressed in the intestinal brush border. Hypomorphic SI variants cause recessive congenital sucrase-isomaltase deficiency (CSID) and related gastrointestinal (GI) symptoms. Among children presenting with chronic, idiopathic loose stools, we assessed the prevalence of CSIDassociated SI variants relative to the general population and the relative GI symptom burden associated with SI genotype within the study population. Methods A prospective study conducted at 18 centers enrolled 308 non-Hispanic white children ≤18 years old who were experiencing chronic, idiopathic, loose stools at least once per week for >4 weeks. Data on demographics, GI symptoms, and genotyping for 37 SI hypomorphic variants were collected. Race/ethnicity-matched SI data from the Exome Aggregation Consortium (ExAC) database was used as the general population reference. Results Compared with the general population, the cumulative prevalence of hypomorphic SI variants was significantly higher in the study population (4.5% vs. 1.3%, P < .01; OR = 3.5 [95% CI: 6.1, 2.0]). Within the study population, children with a hypomorphic SI variant had a more severe GI symptom burden than those without, including: More frequent episodes of loose stools (P < .01), higher overall stool frequency (P < .01), looser stool form (P = .01) and increased flatulence (P = .02). Conclusion Non-Hispanic white children with chronic idiopathic loose stools have a higher prevalence of CSID-associated hypomorphic SI variants than the general population. The GI symptom burden was greater among the study subjects with a hypomorphic SI variant than those without hypomorphic SI variants.

Original languageEnglish
Article numbere0231891
Number of pages9
JournalPLoS ONE
Issue number5
Publication statusPublished - 20 May 2020


  • heterozygosity
  • variant genotypes
  • diarrhea
  • pediatrics
  • diet
  • genotyping
  • medicine and health sciences
  • gastrointestinal tract

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