This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
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.
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