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Genetic and Rare Diseases Information Center (GARD)

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Congenital sucrase-isomaltase deficiency


Other Names for this Disease

  • Congenital sucrose-isomaltase malabsorption
  • CSID
  • Disaccharide intolerance, 1
  • SI deficiency
  • Sucrase-isomaltase deficiency, congenital
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Overview

What is congenital sucrase-isomaltase deficiency (CSID)?

What are the signs and symptoms of congenital sucrase-isomaltase deficiency (CSID)?

How is congenital sucrase-isomaltase deficiency (CSID) diagnosed?

How might congenital sucrase-isomaltase deficiency (CSID) be treated?

What is congenital sucrase-isomaltase deficiency (CSID)?

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

What are the signs and symptoms of congenital sucrase-isomaltase deficiency (CSID)?

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

How is congenital sucrase-isomaltase deficiency (CSID) diagnosed?

CSID can be diagnosed through clinical evaluation, detailed patient history, and tolerance lab tests. Blood tests can be done to look for a flat serum glucose curve after patients are given a dose of sucrose. In addition, blood and urine samples may test positive for sucrose, maltose, or palatinose (a form of maltose) if used during tolerance testing. The feces may also show sucrose, glucose, and fructose, and an acid pH level of below 5.0 or 6.0.[2] 

CSID can be confirmed by taking a small sample of tissue (biopsy) from the small intestine and measuring the activity of the enzyme called sucrase-isomaltase. 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.[2]
Last updated: 7/5/2013

How might congenital sucrase-isomaltase deficiency (CSID) be treated?

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 sucrase from the diet. Sucraid 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.[3] 
Last updated: 7/5/2013

References
  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. April 25, 2008; http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/626/viewAbstract. Accessed 7/5/2013.
  3. Congenital sucrase-isomaltase deficiency . Madisons Foundation. September 2007; http://www.madisonsfoundation.org/index.php?option=com_mpower&task=disease&diseaseID=663. Accessed 7/5/2013.


Other Names for this Disease
  • Congenital sucrose-isomaltase malabsorption
  • CSID
  • Disaccharide intolerance, 1
  • SI deficiency
  • Sucrase-isomaltase deficiency, congenital
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.