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Disease Profile

Congenital sucrase-isomaltase deficiency

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

CSID; Congenital sucrose-isomaltase malabsorption; Sucrose-isomaltase malabsorption, congenital;


Congenital and Genetic Diseases; Digestive Diseases


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]


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]

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.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Watery stool
30%-79% of people have these symptoms
Throwing up
5%-29% of people have these symptoms
Abdominal colic
Abdominal distention
Abdominal bloating
Abdominal swelling
Belly bloating

[ more ]

Percent of people who have these symptoms is not available through HPO
Abnormality of metabolism/homeostasis
Laboratory abnormality
Metabolism abnormality

[ more ]

Autosomal recessive inheritance
Intestinal malabsorption
Kidney stones


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]


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]

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.


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

      Organizations Providing General Support

        Learn more

        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.


            1. Congenital sucrase-isomaltase deficiency. Genetics Home Reference. July 2008; https://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. https://csidcares.org/about/how-is-csid-diagnosed/. Accessed 9/22/2016.

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