Congenital Sucrase-Isomaltase Deficiency
(CSID) is a disorder that affects a person’s ability to digest certain sugars. A person with this condition cannot break down the sugars sucrose and maltose. Sucrose (a sugar found in fruits and also known as table sugar) and maltose (the sugar found in grains) are called disaccharides because they are made up of two simple sugars. Disaccharides are broken down into simple sugars during digestion by intestinal disaccharidase.Sucrose is broken down into glucose and another simple sugar called fructose. Maltose is broken down into two glucose molecules. People with CSID cannot break down sucrose, maltose, and other compounds made from these sugar molecules (carbohydrates).
CSID usually becomes apparent after an infant is weaned and starts 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 gain weight and grow at the expected rate (failure to thrive) and malnutrition. Most affected children are better able to tolerate sucrose and maltose as they get older (1)
The prevalence of CSID is estimated to be 1 in 5,000 people of European descent. This condition is much more prevalent in the native populations of Greenland, Alaska, and Canada, where as many as 1 in 20 people may be affected.
The disease is often missed or misdiagnosed, and may be confused with a number of other diseases if not tested for specifically. Examples of differential diagnosis are congenital intestinal malformations, infectious and post-infectious disease, lactose intolerance, endocrine disorders, pseudomembranous colitis, celiac disease, and cystic fibrosis.
New Research Links Genetic Defects in Carbohydrate Digestion to Irritable Bowel Syndrome (2)
Irritable Bowel Syndrome (IBS) affects a large portion of the general population. New research coordinated by Karolinska Institutet now shows a link between Defective Sucrase-Isomaltase gene variants and IBS. IBS is the most common gastrointestinal disorder. More than 10% of the population suffer from recurrent symptoms including abdominal pain, gas, diarrhea, and constipation. What causes IBS is largely unknown, and this hampers the development of effective treatment for many patients.
Now an international research team led by Karolinska Institutet in Sweden have identified defective sucrase-isomaltase gene variants that increase the risk of IBS. The study is published in the scientific journal, GUT.
By screening 1,887 study participants from multiple centers in Sweden, Italy and the US, they found that rare defective SI mutations were twice more common among IBS cases than healthy controls, and a common variant with reduced enzymatic activity was also associated with increased risk of IBS(3)
The Gold Standard
The Gold Standard for diagnosis of CSID has been distal duodenal biopsies which are analyzed for Disaccharidase (Sucrase, Isomaltase, Lactase, and Palatinase activity). Genesis Laboratory Management, LLC (Genesis Lab) is one of the only 11 or so labs in the country that specialize in analyzing Disaccharidase Assays in-house. Most larger labs, including LabCorp, outsource Disaccharidase assays to one of the 11 labs that perform this testing. There are no commercially available “kits” that can be used to perform such an assay. The sample transport and storage is tedious, requires timeliness and an exact amount of dry ice. The sample analysis is exact and precise, with many minute measurements. A larger lab cannot provide such personal attention to detail as many samples are compromised during transport, storage, or analysis. Thereby, this creates a great inconvenience and frustration to the clinician and the patient. As a result, Disaccharidase Deficiency is significantly under-diagnosed.
At Genesis Lab we spent over a year developing and validating our own Disaccharidase Assay by investing considerable resources. We have clinically validated our methods by comparing our results to that of other labs. We have been offering Disaccharidase testing in New Jersey with pickups arranged through our couriers. We have been receiving great reviews and feedback from happy and satisfied GI providers. Please contact us at 732-686-9291 to arrange for setting up Disaccharidase testing at your healthcare facility.
The treatment of CSID involves a strict and life-long “table-sugar” (sucrose) free diet. However, this is very difficult to adhere to today as much of the processed food we can buy contains sucrose. It is especially difficult for children to adhere to a diet free from sucrose.
In the USA there is an approved pharmaceutical enzyme replacement therapy which can be used to compensate for the lack of an endogenous functioning enzyme. Such supplementation allows a more normal diet, including some intake of sucrose without the development of symptoms.
- 1. Treem, W. R. (2012). Clinical Aspects and Treatment of Congenital Sucrase – Isomaltase Deficiency. Journal of Pediatric Gastroenterology and Nutrition,55(2), S7-S14.
- 2. Henstrom, M., Diekmann, L., Bonfiglio, F., Hadizadeh, F., Kuech, E., Von Kockritz-Blickwede, M., . . . D\’Amato, M. (2018, February). Functional variants in the sucrase-isomaltase gene associate with increased risk of irritable bowel syndrome. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/27872184
- 3. Karolinska Institutet. (2016, November 21). New research links genetic defects in carbohydrate digestion to irritable bowel syndrome. ScienceDaily. Retrieved May 10, 2019 from www.sciencedaily.com/releases/2016/11/161121093514.htm