National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Congenital sucrase-isomaltase deficiency


Other Names:
CSID; Congenital sucrose-isomaltase malabsorption; Sucrose-isomaltase malabsorption, congenital; CSID; Congenital sucrose-isomaltase malabsorption; Sucrose-isomaltase malabsorption, congenital; Disaccharide intolerance, 1; Sucrose intolerance congenital; SI deficiency; Sucrase-isomaltase deficiency, congenital See More
Categories:
Congenital sucrase-isomaltase deficiency (CSID) is a genetic condition that affects a person's ability to digest certain sugars. People with this condition cannot break down the sugars sucrose (a sugar found in fruits, and also known as table sugar) and maltose (the sugar found in grains). CSID usually becomes apparent after an infant begins to consume fruits, juices, and grains. After ingestion of sucrose or maltose, an affected child will typically experience stomach cramps, bloating, excess gas production, and diarrhea. These digestive problems can lead to failure to thrive and malnutrition. Most affected children are better able to tolerate sucrose and maltose as they get older. CSID is inherited in an autosomal recessive pattern and is caused by mutations in the SI gene.[1]
Last updated: 5/17/2011
Affected infants usually develop symptoms soon after they first ingest sucrose, which is found in modified milk formulas, fruits, or starches. Symptoms may include explosive, watery diarrhea resulting in abnormally low levels of body fluids (dehydration), abdominal swelling (distension), and/or abdominal discomfort. In addition, some affected infants may experience malnutrition, resulting from malabsorption of essential nutrients, and/or failure to thrive, resulting from nutritional deficiencies. In some cases, individuals may exhibit irritability; colic; abrasion and/or irritation (excoriation) of the skin on the buttocks as a result of prolonged diarrhea episodes; and/or vomiting.[2]

Symptoms of this disorder vary among affected individuals, but are usually more severe in infants and young children than in adults. Symptoms exhibited in infants and young children are usually more pronounced than those of the affected adults because the diet of younger individuals often includes a higher carbohydrate intake. In addition, the time it takes for intestinal digestion is less in infants or young children.[2]
Last updated: 5/17/2011

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Diarrhea
Watery stool
0002014
30%-79% of people have these symptoms
Vomiting
Throwing up
0002013
5%-29% of people have these symptoms
Abdominal colic 0011848
Abdominal distention
Abdominal bloating
Abdominal swelling
Belly bloating
Bloating
[ more ] 		0003270
Percent of people who have these symptoms is not available through HPO
Abnormality of metabolism/homeostasis
Laboratory abnormality
Metabolism abnormality
[ more ] 		0001939
Autosomal recessive inheritance 0000007
Malabsorption
Intestinal malabsorption
0002024
Nephrolithiasis
Kidney stones
0000787
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Last updated: 7/1/2020
CSID can be diagnosed by taking a small sample of tissue (biopsy) from the small intestine for a specific test known as a disaccharidase assay. Other tests may include a sucrose hydrogen breath test in which an abnormally high level of hydrogen will be detected in the breath of an affected individual after sucrose ingestion. Genetic testing may be indicated in some cases. [2][3]
Last updated: 9/22/2016
CSID is typically treated by modifying a person's diet to reduce the amount of sucrose. Because many foods contain sucrose and other complex sugars, it can be difficult to completely remove sucrose from the diet. Sacrosidase is an oral medication containing the enzyme that does not work properly in people with this condition. By taking this medication, those with CSID can eat sucrose-containing foods because this enzyme will break down sucrose. This medication must be taken with each meal or snack.[2]
Last updated: 12/18/2017

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Congenital sucrase-isomaltase deficiency. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Social Networking Websites

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Financial Resources

  • National Organization for Rare Disorders (NORD) has Disease-Specific Assistance Programs designed to help patients with out-of-pocket costs such as monthly insurance premiums or deductibles. In addition, some programs may provide financial assistance for additional expenses related to a patient's diagnosis such as travel to see a specialist.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on Congenital sucrase-isomaltase deficiency. This website is maintained by the National Library of Medicine.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Congenital sucrase-isomaltase deficiency. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Congenital sucrase-isomaltase deficiency. Genetics Home Reference. July 2008; http://ghr.nlm.nih.gov/condition/congenital-sucrase-isomaltase-deficiency. Accessed 5/17/2011.
  2. Disaccharide Intolerance I. National Organization for Rare Disorders. 2005; https://rarediseases.org/rare-diseases/disaccharide-intolerance-i/.
  3. How is CSID diagnosed?. CSIDcares. http://csidcares.org/about/how-is-csid-diagnosed/. Accessed 9/22/2016.