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Danialifar TF, Chumpitazi BP, Mehta DI, Di Lorenzo C. Genetic and acquired sucrase-isomaltase deficiency: A clinical review. J Pediatr Gastroenterol Nutr 2024; 78:774-782. [PMID: 38327254 DOI: 10.1002/jpn3.12151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 01/05/2024] [Accepted: 01/19/2024] [Indexed: 02/09/2024]
Abstract
Genetic sucrase-isomaltase deficiency (GSID) is an inherited deficiency in the ability to digest sucrose and potentially starch due to mutations in the sucrase-isomaltase (SI) gene. Congenital sucrase-isomaltase deficiency is historically considered to be a rare condition affecting infants with chronic diarrhea as exposure to dietary sucrose begins. Growing evidence suggests that individuals with SI variants may present later in life, with symptoms overlapping with those of irritable bowel syndrome. The presence of SI genetic variants may, either alone or in combination, affect enzyme activity and lead to symptoms of different severity. As such, a more appropriate term for this inherited condition is GSID, with a recognition of a spectrum of severity and onset of presentation. Currently, disaccharidase assay on duodenal mucosal tissue homogenates is the gold standard in diagnosing SI deficiency. A deficiency in the SI enzyme can be present at birth (genetic) or acquired later, often in association with damage to the enteric brush-border membrane. Other noninvasive diagnostic alternatives such as sucrose breath tests may be useful but require further validation. Management of GSID is based on sucrose and potentially starch restriction tailored to the individual patients' tolerance and symptoms. As this approach may be challenging, additional treatment with commercially available sacrosidase is available. However, some patients may require continued starch restriction. Further research is needed to clarify the true prevalence of SI deficiency, the pathobiology of single SI heterozygous mutations, and to define optimal diagnostic and treatment algorithms in the pediatric population.
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Affiliation(s)
- Tanaz Farzan Danialifar
- Children's Hospital Los Angeles, Los Angeles, California, USA
- Keck School of Medicine of USC, Los Angeles, California, USA
| | - Bruno P Chumpitazi
- Department of Pediatrics, Duke University School of Medicine, Durham, North Carolina, USA
- Duke Clinical Research Institute, Durham, North Carolina, USA
| | - Devendra I Mehta
- Center for Digestive Health and Nutrition, Arnold Palmer Hospital for Children, Orlando, Florida, USA
| | - Carlo Di Lorenzo
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Nationwide Children's Hospital, Columbus, Ohio, USA
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2
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Senftleber NK, Ramne S, Moltke I, Jørgensen ME, Albrechtsen A, Hansen T, Andersen MK. Genetic Loss of Sucrase-Isomaltase Function: Mechanisms, Implications, and Future Perspectives. Appl Clin Genet 2023; 16:31-39. [PMID: 36994449 PMCID: PMC10041990 DOI: 10.2147/tacg.s401712] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/10/2023] [Indexed: 03/31/2023] Open
Abstract
Genetic variants causing loss of sucrase-isomaltase (SI) function result in malabsorption of sucrose and starch components and the condition congenital sucrase-isomaltase deficiency (CSID). The identified genetic variants causing CSID are very rare in all surveyed populations around the globe, except the Arctic-specific c.273_274delAG loss-of-function (LoF) variant, which is common in the Greenlandic Inuit and other Arctic populations. In these populations, it is, therefore, possible to study people with loss of SI function in an unbiased way to elucidate the physiological function of SI, and investigate both short-term and long-term health effects of reduced small intestinal digestion of sucrose and starch. Importantly, a recent study of the LoF variant in Greenlanders reported that adult homozygous carriers have a markedly healthier metabolic profile. These findings indicate that SI inhibition could potentially improve metabolic health also in individuals not carrying the LoF variant, which is of great interest considering the massive number of individuals with obesity and type 2 diabetes worldwide. Therefore, the objectives of this review, are 1) to describe the biological role of SI, 2) to describe the metabolic impact of the Arctic SI LoF variant, 3) to reflect on potential mechanisms linking reduced SI function to metabolic health, and 4) to discuss what knowledge is necessary to properly evaluate whether SI inhibition is a potential therapeutic target for improving cardiometabolic health.
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Affiliation(s)
- Ninna Karsbæk Senftleber
- Clinical Research, Copenhagen University Hospital – Steno Diabetes Center Copenhagen, Herlev, Denmark
| | - Stina Ramne
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ida Moltke
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Marit Eika Jørgensen
- Clinical Research, Copenhagen University Hospital – Steno Diabetes Center Copenhagen, Herlev, Denmark
- Centre for Public Health in Greenland, National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark
- Steno Diabetes Center Greenland, Nuuk, Greenland
| | - Anders Albrechtsen
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Torben Hansen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mette K Andersen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Correspondence: Mette K Andersen, University of Copenhagen, Blegdamsvej 3B, Mærsk Tårnet, 8. sal, 2200 København N., Copenhagen, Denmark, Tel +45 35325282, Email
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Apgar TL, Sanders CR. Compendium of causative genes and their encoded proteins for common monogenic disorders. Protein Sci 2022; 31:75-91. [PMID: 34515378 PMCID: PMC8740837 DOI: 10.1002/pro.4183] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/29/2021] [Accepted: 08/31/2021] [Indexed: 01/19/2023]
Abstract
A compendium is presented of inherited monogenic disorders that have a prevalence of >1:20,000 in the human population, along with their causative genes and encoded proteins. "Simple" monogenic diseases are those for which the clinical features are caused by mutations impacting a single gene, usually in a manner that alters the sequence of the encoded protein. Of course, for a given "monogenic disorder", there is sometimes more than one potential disease gene, mutations in any one of which is sufficient to cause phenotypes of that disorder. Disease-causing mutations for monogenic disorders are usually passed on from generation to generation in a Mendelian fashion, and originate from spontaneous (de novo) germline founder mutations. In the past monogenic disorders have often been written off as targets for drug discovery because they sometimes are assumed to be rare disorders, for which the meager projected financial payoff of drug discovery and development has discouraged investment. However, not all monogenic diseases are rare. Here, we report that that currently available data identifies 72 disorders with a prevalence of at least 1 in 20,000 humans. For each, we tabulate the gene(s) for which mutations cause the spectrum of phenotypes associated with that disorder. We also identify the gene and protein that most commonly causes each disease. 34 of these disorders are caused exclusively by mutations in only a single gene and encoded protein.
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Affiliation(s)
- Tucker L. Apgar
- Department of Biochemistry and Center for Structural BiologyVanderbilt University School of Medicine Basic SciencesNashvilleTennesseeUSA
| | - Charles R. Sanders
- Department of Biochemistry and Center for Structural BiologyVanderbilt University School of Medicine Basic SciencesNashvilleTennesseeUSA
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Das B, Okamoto K, Rabalais J, Young JA, Barrett KE, Sivagnanam M. Aberrant Epithelial Differentiation Contributes to Pathogenesis in a Murine Model of Congenital Tufting Enteropathy. Cell Mol Gastroenterol Hepatol 2021; 12:1353-1371. [PMID: 34198013 PMCID: PMC8479479 DOI: 10.1016/j.jcmgh.2021.06.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 06/18/2021] [Accepted: 06/21/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Congenital tufting enteropathy (CTE) is an intractable diarrheal disease of infancy caused by mutations of epithelial cell adhesion molecule (EpCAM). The cellular and molecular basis of CTE pathology has been elusive. We hypothesized that the loss of EpCAM in CTE results in altered lineage differentiation and defects in absorptive enterocytes thereby contributing to CTE pathogenesis. METHODS Intestine and colon from mice expressing a CTE-associated mutant form of EpCAM (mutant mice) were evaluated for specific markers by quantitative real-time polymerase chain reaction, Western blotting, and immunostaining. Body weight, blood glucose, and intestinal enzyme activity were also investigated. Enteroids derived from mutant mice were used to assess whether the decreased census of major secretory cells could be rescued. RESULTS Mutant mice exhibited alterations in brush-border ultrastructure, function, disaccharidase activity, and glucose absorption, potentially contributing to nutrient malabsorption and impaired weight gain. Altered cell differentiation in mutant mice led to decreased enteroendocrine cells and increased numbers of nonsecretory cells, though the hypertrophied absorptive enterocytes lacked key features, causing brush border malfunction. Further, treatment with the Notch signaling inhibitor, DAPT, increased the numbers of major secretory cell types in mutant enteroids (graphical abstract 1). CONCLUSIONS Alterations in intestinal epithelial cell differentiation in mutant mice favor an increase in absorptive cells at the expense of major secretory cells. Although the proportion of absorptive enterocytes is increased, they lack key functional properties. We conclude that these effects underlie pathogenic features of CTE such as malabsorption and diarrhea, and ultimately the failure to thrive seen in patients.
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Affiliation(s)
- Barun Das
- Department of Pediatrics, University of California, San Diego, La Jolla, California
| | - Kevin Okamoto
- Department of Pediatrics, University of California, San Diego, La Jolla, California
| | - John Rabalais
- Department of Pediatrics, University of California, San Diego, La Jolla, California
| | - Jocelyn A. Young
- Department of Pediatrics, University of California, San Diego, La Jolla, California,Department of Pediatrics, Rady Children’s Hospital, San Diego, California
| | - Kim E. Barrett
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Mamata Sivagnanam
- Department of Pediatrics, University of California, San Diego, La Jolla, California,Department of Pediatrics, Rady Children’s Hospital, San Diego, California,Correspondence Address correspondence to: Mamata Sivagnanam, MD, Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, 9500 Gilman Drive, La Jolla, CA 92093. fax: 858-967-8917.
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Zhou J, Zhao Y, Qian X, Cheng Y, Cai H, Chen M, Zhou S. Two Novel Mutations in the SI Gene Associated With Congenital Sucrase-Isomaltase Deficiency: A Case Report in China. Front Pediatr 2021; 9:731716. [PMID: 34926337 PMCID: PMC8675567 DOI: 10.3389/fped.2021.731716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 10/11/2021] [Indexed: 11/16/2022] Open
Abstract
Background: Congenital sucrase-isomaltase deficiency (CSID) is an autosomal recessive inherited disease that leads to the maldigestion of disaccharides and is associated with mutation of the sucrase-isomaltase (SI) gene. Cases of CSID are not very prevalent in China or worldwide but are gradually being identified and reported. Case Presentation: We report a case involving a 14-month-old male who presented with failure to thrive that had begun after food diversification and was admitted for chronic diarrhea. We used a whole-exome sequencing (WES) approach to identify mutations in this patient's genome. WES revealed two novel heterozygous mutations in the SI gene, c.2626C > T (p.Q876*) and c.2872C > T (p.R958C), which were confirmed by Sanger DNA sequencing. With a strict sucrose- and starch-restricted diet, the patient's diarrhea was resolved, and he began to gain weight. Conclusions: We report a case of novel variants in the SI gene that caused CSID. This report provides valuable information for the clinical field, especially in China.
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Affiliation(s)
- Jianli Zhou
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
| | - Yuzhen Zhao
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
| | - Xia Qian
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
| | - Yongwei Cheng
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
| | - Huabo Cai
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
| | - Moxian Chen
- Key Laboratory of National Forestry and Grassland Administration on Subtropical Forest Biodiversity Conservation, College of Biology and the Environment, Nanjing Forestry University, Nanjing, China
| | - Shaoming Zhou
- Division of Gastroenterology, Shenzhen Children's Hospital, Shenzhen, China
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Chumpitazi BP, Lewis J, Cooper D, D’Amato M, Lim J, Gupta S, Miranda A, Terry N, Mehta D, Scheimann A, O’Gorman M, Tipnis N, Davies Y, Friedlander J, Smith H, Punati J, Khlevner J, Setty M, Di Lorenzo C. Hypomorphic SI genetic variants are associated with childhood chronic loose stools. PLoS One 2020; 15:e0231891. [PMID: 32433684 PMCID: PMC7239456 DOI: 10.1371/journal.pone.0231891] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 04/02/2020] [Indexed: 11/18/2022] Open
Abstract
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 CSID-associated 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.
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Affiliation(s)
| | - Jeffery Lewis
- Children’s Center for Digestive Health Care, Atlanta, GA, United States of America
| | - Derick Cooper
- QOL Medical, LLC, Vero Beach, FL, United States of America
| | - Mauro D’Amato
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Joel Lim
- Children's Mercy Hospital, Kansas City, MO, United States of America
| | - Sandeep Gupta
- Sacramento Pediatric Gastroenterology, Sacramento, CA, United States of America
| | - Adrian Miranda
- Children’s Hospital of Wisconsin, Milwaukee, WI, United States of America
| | - Natalie Terry
- Children’s Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Devendra Mehta
- Arnold Palmer Children's Hospital, Orlando, FL, United States of America
| | - Ann Scheimann
- Johns Hopkins University, Baltimore, MD, United States of America
| | - Molly O’Gorman
- Primary Children's Medical Center, Salt Lake City, UT, United States of America
| | - Neelesh Tipnis
- University of Mississippi Medical Center, Jackson, MS, United States of America
| | - Yinka Davies
- Sacramento Pediatric Gastroenterology, Sacramento, CA, United States of America
| | - Joel Friedlander
- Children’s Hospital Colorado, Digestive Health Institute, University of Colorado School of Medicine, Aurora, CO, United States of America
| | - Heather Smith
- QOL Medical, LLC, Vero Beach, FL, United States of America
| | - Jaya Punati
- Children’s Hospital of Los Angeles, Los Angeles, CA, United States of America
| | - Julie Khlevner
- Columbia University Medical Center, New York, NY, United States of America
| | - Mala Setty
- UCSF Benioff Children’s Hospital Oakland, Oakland, CA, United States of America
| | - Carlo Di Lorenzo
- Department of Pediatrics, The Ohio State University, Columbus, OH, United States of America
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Abstract
PURPOSE OF REVIEW Disaccharidase testing, as applied to the evaluation of gastrointestinal disturbances is available but it is not routinely considered in the diagnostic work-up. The purpose of this review was to determine if disaccharidase testing is clinically useful and to consider how the results could alter patient management. RECENT FINDINGS Indicate that carbohydrate maldigestion could contribute functional bowel disorders and negatively impact the fecal microbiome. Diagnostic techniques include enzyme activity assays performed on random endoscopically obtained small intestinal biopsies, immunohistochemistry, stable isotope tracer and nonenriched substrate load breath testing, and genetic testing for mutations. More than 40 sucrase--isomaltase gene variants coding for defective or reduced enzymatic activity have been reported and deficiency conditions are more common than previously thought. SUMMARY The rationale for disaccharidase activity testing relates to a need to fully assess unexplained recurrent abdominal discomfort and associated symptoms. All disaccharidases share the same basic mechanism of mucosal expression and deficiency has far reaching consequences. Testing for disaccharidase expression appears to have an important role in symptom evaluation, but there are accuracy and logistical issues that should be considered. It is likely that specific recommendations for patient management, dietary modification, and enzyme supplementation would come from better testing methods.
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Affiliation(s)
- Antone R. Opekun
- Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
- Department of Pediatrics, Section of Gastroenterology, Hepatology and Nutrition, Baylor College of Medicine, Houston, TX, USA
- Section of Gastroenterology, Hepatology and Nutrition, Texas Children’s Hospital, Houston, TX, USA
| | - Bruno P. Chumpitazi
- Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
- Department of Pediatrics, Section of Gastroenterology, Hepatology and Nutrition, Baylor College of Medicine, Houston, TX, USA
- Section of Gastroenterology, Hepatology and Nutrition, Texas Children’s Hospital, Houston, TX, USA
| | - Mustafa M. Abdulsada
- Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA
| | - Buford L Nichols
- Department of Pediatrics, Section of Gastroenterology, Hepatology and Nutrition, Baylor College of Medicine, Houston, TX, USA
- Director Emeritus, USDA/ARS Children’s Nutrition Research Center, Houston, TX, USA
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Heterozygotes Are a Potential New Entity among Homozygotes and Compound Heterozygotes in Congenital Sucrase-Isomaltase Deficiency. Nutrients 2019; 11:nu11102290. [PMID: 31557950 PMCID: PMC6835860 DOI: 10.3390/nu11102290] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/19/2019] [Accepted: 09/23/2019] [Indexed: 12/12/2022] Open
Abstract
Congenital sucrase-isomaltase deficiency (CSID) is an autosomal recessive disorder of carbohydrate maldigestion and malabsorption caused by mutations in the sucrase-isomaltase (SI) gene. SI, together with maltase-glucoamylase (MGAM), belongs to the enzyme family of disaccharidases required for breakdown of α-glycosidic linkages in the small intestine. The effects of homozygote and compound heterozygote inheritance trait of SI mutations in CSID patients have been well described in former studies. Here we propose the inclusion of heterozygote mutation carriers as a new entity in CSID, possibly presenting with milder symptoms. The hypothesis is supported by recent observations of heterozygote mutation carriers among patients suffering from CSID or patients diagnosed with functional gastrointestinal disorders. Recent studies implicate significant phenotypic heterogeneity depending on the character of the mutation and call for more research regarding the correlation of genetics, function at the cellular and molecular level and clinical presentation. The increased importance of SI gene variants in irritable bowel syndrome (IBS) or other functional gastrointestinal disorders FGIDs and their available symptom relief diets like fermentable oligo-, di-, mono-saccharides and polyols FODMAPs suggest that the heterozygote mutants may affect the disease development and treatment.
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Abstract
The final step of carbohydrate digestion in the intestine is performed by 2 major α-glucosidases of the intestinal mucosa, sucrase-isomaltase (SI) and maltase-glucoamylase. Both of these enzymes are type II membrane glycoproteins, which share a significant level of homology in gene and protein structures and yet have differences in the posttranslational processing, substrate specificity and functional capacity. Insufficient activity of these disaccharidases particularly SI as a result of genetic mutations or secondary intestinal pathologies is associated with carbohydrate maldigestion and gastrointestinal intolerances. This review will discuss the maturation profiles of SI and maltase-glucoamylase relative to their functional capacities and deficiencies.
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Congenital Sucrase-isomaltase Deficiency: A Novel Compound Heterozygous Mutation Causing Aberrant Protein Localization. J Pediatr Gastroenterol Nutr 2017; 64:770-776. [PMID: 27749612 PMCID: PMC8176889 DOI: 10.1097/mpg.0000000000001424] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES Congenital diarrheal disorders is a group of inherited enteropathies presenting in early life and requiring parenteral nutrition. In most cases, genetics may be the key for precise diagnosis. We present an infant girl with chronic congenital diarrhea that resolved after introduction of fructose-based formula but had no identified mutation in the SLC5A1 gene. Using whole exome sequencing (WES) we identified other mutations that better dictated dietary adjustments. METHODS WES of the patient and her parents was performed. The analysis focused on recessive model including compound heterozygous mutations. Sanger sequencing was used to validate identified mutations and to screen the patient's newborn sister and grandparents. Expression and localization analysis were performed in the patient's duodenal biopsies using immunohistochemistry. RESULTS Using WES we identified a new compound heterozygote mutation in sucrase-isomaltase (SI) gene; a maternal inherited known V577G mutation, and a novel paternal inherited C1531W mutation. Importantly, the newborn offspring carried similar compound heterozygous mutations. Computational predictions suggest that both mutations highly destabilize the protein. SI expression and localization studies determined that the mutated SI protein was not expressed on the brush border membrane in the patient's duodenal biopsies, verifying the diagnosis of congenital sucrase-isomaltase deficiency (CSID). CONCLUSIONS The novel compound heterozygote V577G/C1531W SI mutations lead to lack of SI expression in the duodenal brush border, confirming the diagnosis of CSID. These cases of CSID extend the molecular spectrum of this condition, further directing a more adequate dietary intervention for the patient and newborn sibling.
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Molecular pathogenicity of novel sucrase-isomaltase mutations found in congenital sucrase-isomaltase deficiency patients. Biochim Biophys Acta Mol Basis Dis 2017; 1863:817-826. [PMID: 28062276 DOI: 10.1016/j.bbadis.2016.12.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/15/2016] [Accepted: 12/30/2016] [Indexed: 01/03/2023]
Abstract
BACKGROUND & AIMS Congenital sucrase-isomaltase deficiency (CSID) is a genetic disorder associated with mutations in the sucrase-isomaltase (SI) gene. The diagnosis of congenital diarrheal disorders like CSID is difficult due to unspecific symptoms and usually requires invasive biopsy sampling of the intestine. Sequencing of the SI gene and molecular analysis of the resulting potentially pathogenic SI protein variants may facilitate a diagnosis in the future. This study aimed to categorize SI mutations based on their functional consequences. METHODS cDNAs encoding 13 SI mutants were expressed in COS-1 cells. The molecular pathogenicity of the resulting SI mutants was defined by analyzing their biosynthesis, cellular localization, structure and enzymatic functions. RESULTS Three biosynthetic phenotypes for the novel SI mutations were identified. The first biosynthetic phenotype was defined by mutants that are intracellularly transported in a fashion similar to wild type SI and with normal, but varying, levels of enzymatic activity. The second biosynthetic phenotype was defined by mutants with delayed maturation and trafficking kinetics and reduced activity. The third group of mutants is entirely transport incompetent and functionally inactive. CONCLUSIONS The current study unraveled CSID as a multifaceted malabsorption disorder that comprises three major classes of functional and trafficking mutants of SI and established a gradient of mild to severe functional deficits in the enzymatic functions of the enzyme. GENERAL SIGNIFICANCE This novel concept and the existence of mild consequences in a number of SI mutants strongly propose that CSID is an underdiagnosed and a more common intestinal disease than currently known.
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Overeem AW, Posovszky C, Rings EHMM, Giepmans BNG, van IJzendoorn SCD. The role of enterocyte defects in the pathogenesis of congenital diarrheal disorders. Dis Model Mech 2016; 9:1-12. [PMID: 26747865 PMCID: PMC4728335 DOI: 10.1242/dmm.022269] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Congenital diarrheal disorders are rare, often fatal, diseases that are difficult to diagnose (often requiring biopsies) and that manifest in the first few weeks of life as chronic diarrhea and the malabsorption of nutrients. The etiology of congenital diarrheal disorders is diverse, but several are associated with defects in the predominant intestinal epithelial cell type, enterocytes. These particular congenital diarrheal disorders (CDDENT) include microvillus inclusion disease and congenital tufting enteropathy, and can feature in other diseases, such as hemophagocytic lymphohistiocytosis type 5 and trichohepatoenteric syndrome. Treatment options for most of these disorders are limited and an improved understanding of their molecular bases could help to drive the development of better therapies. Recently, mutations in genes that are involved in normal intestinal epithelial physiology have been associated with different CDDENT. Here, we review recent progress in understanding the cellular mechanisms of CDDENT. We highlight the potential of animal models and patient-specific stem-cell-based organoid cultures, as well as patient registries, to integrate basic and clinical research, with the aim of clarifying the pathogenesis of CDDENT and expediting the discovery of novel therapeutic strategies. Summary: Overview of the recent progress in our understanding of congenital diarrheal disorders, and the available models to study these diseases.
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Affiliation(s)
- Arend W Overeem
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Carsten Posovszky
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, 89075 Ulm, Germany
| | - Edmond H M M Rings
- Department of Pediatrics, Erasmus Medical Center Rotterdam, Erasmus University Rotterdam, 3000 CB Rotterdam, The Netherlands Department of Pediatrics, Leiden University Medical Center, Leiden University, 2300 RC Leiden, The Netherlands
| | - Ben N G Giepmans
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Sven C D van IJzendoorn
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, 9713 AV Groningen, The Netherlands
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13
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Diagnosing and Treating Intolerance to Carbohydrates in Children. Nutrients 2016; 8:157. [PMID: 26978392 PMCID: PMC4808885 DOI: 10.3390/nu8030157] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 02/22/2016] [Accepted: 02/25/2016] [Indexed: 12/19/2022] Open
Abstract
Intolerance to carbohydrates is relatively common in childhood, but still poorly recognized and managed. Over recent years it has come to the forefront because of progresses in our knowledge on the mechanisms and treatment of these conditions. Children with intolerance to carbohydrates often present with unexplained signs and symptoms. Here, we examine the most up-to-date research on these intolerances, discuss controversies relating to the diagnostic approach, including the role of molecular analysis, and provide new insights into modern management in the pediatric age, including the most recent evidence for correct dietary treatment.
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Rodríguez D, Ramsay AJ, Quesada V, Garabaya C, Campo E, Freije JMP, López-Otín C. Functional analysis of sucrase–isomaltase mutations from chronic lymphocytic leukemia patients. Hum Mol Genet 2013; 22:2273-82. [DOI: 10.1093/hmg/ddt078] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Investigations of the structures and inhibitory properties of intestinal maltase glucoamylase and sucrase isomaltase. J Pediatr Gastroenterol Nutr 2012; 55 Suppl 2:S20-4. [PMID: 23103645 DOI: 10.1097/01.mpg.0000421403.34763.71] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
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Congenital sucrase-isomaltase deficiency: heterogeneity of inheritance, trafficking, and function of an intestinal enzyme complex. J Pediatr Gastroenterol Nutr 2012; 55 Suppl 2:S13-20. [PMID: 23103643 DOI: 10.1097/01.mpg.0000421402.57633.4b] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
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Le MT, Frye RF, Rivard CJ, Cheng J, McFann KK, Segal MS, Johnson RJ, Johnson JA. Effects of high-fructose corn syrup and sucrose on the pharmacokinetics of fructose and acute metabolic and hemodynamic responses in healthy subjects. Metabolism 2012; 61:641-51. [PMID: 22152650 PMCID: PMC3306467 DOI: 10.1016/j.metabol.2011.09.013] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 09/06/2011] [Accepted: 09/27/2011] [Indexed: 02/07/2023]
Abstract
It is unclear whether high-fructose corn syrup (HFCS), which contains a higher amount of fructose and provides an immediate source of free fructose, induces greater systemic concentrations of fructose as compared with sucrose. It is also unclear whether exposure to higher levels of fructose leads to increased fructose-induced adverse effects. The objective was to prospectively compare the effects of HFCS- vs sucrose-sweetened soft drinks on acute metabolic and hemodynamic effects. Forty men and women consumed 24 oz of HFCS- or sucrose-sweetened beverages in a randomized crossover design study. Blood and urine samples were collected over 6 hours. Blood pressure, heart rate, fructose, and a variety of other metabolic biomarkers were measured. Fructose area under the curve and maximum concentration, dose-normalized glucose area under the curve and maximum concentration, relative bioavailability of glucose, changes in postprandial concentrations of serum uric acid, and systolic blood pressure maximum levels were higher when HFCS-sweetened beverages were consumed as compared with sucrose-sweetened beverages. Compared with sucrose, HFCS leads to greater fructose systemic exposure and significantly different acute metabolic effects.
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Affiliation(s)
- MyPhuong T. Le
- Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, FL 32610
| | - Reginald F. Frye
- Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, FL 32610
| | - Christopher J. Rivard
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, CO 80045
| | - Jing Cheng
- Department of Epidemiology and Health Policy Research, University of FL, Gainesville, FL 32610
| | - Kim K. McFann
- Department of Biostatistics and Informatics, University of Colorado Denver, Aurora, CO 80045
| | - Mark S. Segal
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, FL 32610
| | - Richard J. Johnson
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, CO 80045
| | - Julie A. Johnson
- Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, FL 32610
- Address correspondence to Julie A. Johnson, Department of Pharmacotherapy and Translation Research, College of Pharmacy, University of Florida, PO BOX 100486, Gainesville, FL 32610. Phone (352) 273-6007, Fax (352) 273-6121, and
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Congenital and putatively acquired forms of sucrase-isomaltase deficiency in infancy: effects of sacrosidase therapy. J Pediatr Gastroenterol Nutr 2009; 49:485-7. [PMID: 19680155 DOI: 10.1097/mpg.0b013e3181a4c0df] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
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Alfalah M, Keiser M, Leeb T, Zimmer KP, Naim HY. Compound heterozygous mutations affect protein folding and function in patients with congenital sucrase-isomaltase deficiency. Gastroenterology 2009; 136:883-92. [PMID: 19121318 DOI: 10.1053/j.gastro.2008.11.038] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 10/31/2008] [Accepted: 11/13/2008] [Indexed: 12/30/2022]
Abstract
BACKGROUND & AIMS Congenital sucrase-isomaltase (SI) deficiency is an autosomal-recessive intestinal disorder characterized by a drastic reduction or absence of sucrase and isomaltase activities. Previous studies have indicated that single mutations underlie individual phenotypes of the disease. We investigated whether compound heterozygous mutations, observed in some patients, have a role in disease pathogenesis. METHODS We introduced mutations into the SI complementary DNA that resulted in the amino acid substitutions V577G and G1073D (heterozygous mutations found in one group of patients) or C1229Y and F1745C (heterozygous mutations found in another group). The mutant genes were expressed transiently, alone or in combination, in COS cells and the effects were assessed at the protein, structural, and subcellular levels. RESULTS The mutants SI-V577G, SI-G1073D, and SI-F1745C were misfolded and could not exit the endoplasmic reticulum, whereas SI-C1229Y was transported only to the Golgi apparatus. Co-expression of mutants found on each SI allele in patients did not alter the protein's biosynthetic features or improve its enzymatic activity. Importantly, the mutations C1229Y and F1745C, which lie in the sucrase domains of SI, prevented its targeting to the cell's apical membrane but did not affect protein folding or isomaltase activity. CONCLUSIONS Compound heterozygosity is a novel pathogenic mechanism of congenital SI deficiency. The effects of mutations in the sucrase domain of SIC1229Y and SIF1745C indicate the importance of a direct interaction between isomaltase and sucrose and the role of sucrose as an intermolecular chaperone in the intracellular transport of SI.
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Affiliation(s)
- Marwan Alfalah
- Department of Physiological Chemistry, University of Veterinary Medicine, Hannover, Germany
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Keiser M, Alfalah M, Pröpsting MJ, Castelletti D, Naim HY. Altered Folding, Turnover, and Polarized Sorting Act in Concert to Define a Novel Pathomechanism of Congenital Sucrase-Isomaltase Deficiency. J Biol Chem 2006; 281:14393-9. [PMID: 16543230 DOI: 10.1074/jbc.m513631200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Naturally occurring mutants of membrane and secretory proteins are often associated with the pathogenesis of human diseases. Here, we describe the molecular basis of a novel phenotype of congenital sucrase-isomaltase deficiency (CSID), a disaccharide malabsorption disorder of the human intestine in which several structural features and functional capacities of the brush-border enzyme complex sucrase-isomaltase (SI) are affected. The cDNA encoding SI from a patient with CSID reveals a mutation in the isomaltase subunit of SI that results in the substitution of a cysteine by an arginine at amino acid residue 635 (C635R). When this mutation is introduced into the wild type cDNA of SI a mutant enzyme, SI(C635R), is generated that shows a predominant localization in the endoplasmic reticulum. Nevertheless, a definite localization of SI(C635R) in the Golgi apparatus and at the cell surface could be also observed. Epitope mapping with conformation-specific mAbs protease sensitivity assays, and enzymatic activity measurements demonstrate an altered folding pattern of SI(C635R) that is responsible for a substantially increased turnover rate and an aberrant sorting profile. Thus, SI(C635R) becomes distributed also at the basolateral membrane in contrast to wild type SI. Concomitant with the altered sorting pattern, the partial detergent extractability of wild type SI shifts to a complete detergent solubility with Triton X-100. The mutation has therefore affected an epitope responsible for the apical targeting fidelity of SI. Altogether, the combined effects of the C635R mutation on the turnover rate, function, polarized sorting, and detergent solubility of SI constitute a unique and novel pathomechanism of CSID.
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Affiliation(s)
- Markus Keiser
- Department of Physiological Chemistry, University of Veterinary Medicine Hannover, D-30559 Hannover, Germany
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Robayo-Torres CC, Quezada-Calvillo R, Nichols BL. Disaccharide digestion: clinical and molecular aspects. Clin Gastroenterol Hepatol 2006; 4:276-87. [PMID: 16527688 DOI: 10.1016/j.cgh.2005.12.023] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Sugars normally are absorbed in the small intestine. When carbohydrates are malabsorbed, the osmotic load produced by the high amount of low molecular weight sugars and partially digested starches in the small intestine can cause symptoms of intestinal distention, rapid peristalsis, and diarrhea. Colonic bacteria normally metabolize proximally malabsorbed dietary carbohydrate through fermentation to small fatty acids and gases (ie, hydrogen, methane, and carbon dioxide). When present in large amounts, the malabsorbed sugars and starches can be excreted in the stool. Sugar intolerance is the presence of abdominal symptoms related to the proximal or distal malabsorption of dietary carbohydrates. The symptoms consist of meal-related abdominal cramps and distention, increased flatulence, borborygmus, and diarrhea. Infants and young children with carbohydrate malabsorption show more intense symptoms than adults; the passage of undigested carbohydrates through the colon is more rapid and is associated with detectable carbohydrates in copious watery acid stools. Dehydration often follows feeding of the offending sugar. In this review we present the clinical and current molecular aspects of disaccharidase digestion.
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Affiliation(s)
- Claudia C Robayo-Torres
- Department of Pediatrics, USDA/ARS, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030, USA
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Pröpsting MJ, Kanapin H, Jacob R, Naim HY. A phenylalanine-based folding determinant in intestinal sucrase-isomaltase that functions in the context of a quality control mechanism beyond the endoplasmic reticulum. J Cell Sci 2005; 118:2775-84. [PMID: 15944403 DOI: 10.1242/jcs.02364] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phenotype II of congenital sucrase-isomaltase deficiency in man is characterized by a retention of the brush border protein sucrase-isomaltase (SI) in the ER/cis-Golgi intermediate compartment (ERGIC) and the cis-Golgi. The transport block is due to the substitution of a glutamine by a proline at amino acid residue 1098 that generates a temperature-sensitive mutant enzyme, SIQ1098P, the transport of which is regulated by several cycles of anterograde and retrograde transport between the ER and the cis-Golgi (Propsting, M. J., Jacob, R. and Naim, H. Y. (2003). J. Biol. Chem. 278, 16310-16314). A quality control beyond the ER has been proposed that implicates a retention signal or a folding determinant elicited by the Q1098P mutation. We have used alanine-scanning mutagenesis to screen upstream and downstream regions flanking Q1098 and identified a putative motif, F1093-x-F1095-x-x-x-F1099 that is likely to be implicated in sensing the folding and subsequent trafficking of SI from the ER to the Golgi. The characteristics of this motif are three phenylalanine residues that upon substitution by alanine generate the temperature-sensitive SIQ1098P phenotype. This mutant protein undergoes transport arrest in the ERGIC and cis-Golgi compartments and acquires correct folding and functional activity at reduced temperatures as a consequence of cycles of anterograde and retrograde transport between the ER and cis-Golgi. Other amino acid residues in this motif are not significant in the context of phenotype II. We propose that the phenylalanine cluster is required for shielding a folding determinant in the extracellular domain of SI; substitution of a Q by a P at residue 1098 of sucrase disrupts this determinant and elicits retention of SIQ1098P in ERGIC and cis-Golgi in phenotype II of CSID.
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Affiliation(s)
- Marcus J Pröpsting
- Department of Physiological Chemistry, University of Veterinary Medicine Hannover, Germany
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