Sucrose Isomaltase Deficiency

What is disaccharidase deficiency?

Disaccharidases are a group of enzymes in the lining of the small intestines. These enzymes are needed to digest sugars called disaccharides, which include lactose, sucrose, and maltose. The enzymes break disaccharides into simple sugars such as glucose and fructose, which can be absorbed by the body to provide energy. Disaccharidase deficiency is a condition in which a child’s small intestine lacks the enzymes needed to digest disaccharides. 

What are the different types of disaccharidases?

There are several types of disaccharidase enzymes. The most common are:

• Lactase: Helps breakdown lactose into glucose and galactose.
• Sucrase: Helps breakdown sucrose into glucose and fructose.
• Maltase: Helps breakdown maltose into two glucose molecules.
• Isomaltase: Helps breakdown sucrose, maltose, and some products of starch.

What are the different types of disaccharidase deficiencies?

• Lactase deficiency: Difficulty digesting lactose sugar, which is found in milk.
• Sucrase deficiency: Difficulty digesting table sugar (sucrose).
• Maltase deficiency: Difficulty digesting starches.
• Isomaltase deficiency: Difficulty digesting sucrose, maltose, and some complex starches.

How common is disaccharidase deficiency?

In children, disaccharidase deficiencies are relatively common. While the exact numbers are unclear, disaccharidase deficiencies may account for up to 50% of patients with unexplained gastrointestinal symptoms. In children, lactase deficiency (lactose intolerance) is the most common form, followed by congenital sucrase-isomaltase deficiency (CSID) and pan-disaccharidase enzyme deficiency [1]. 

What causes disaccharidase deficiency?

Several factors can cause disaccharidase deficiency. Primary or genetic factors are inherited. This means that children are born without the ability to produce these enzymes in their small intestines. These deficiencies are permanent, and patients exhibit symptoms soon after their first feeding.

Secondary or acquired causes for disaccharidase deficiency are usually due to damage to the lining of the small intestine. This can be from factors such as infections, inflammation, or medications. In these cases, addressing the underlying factor may help resolve the issue. 

What are the symptoms of disaccharidase deficiency?

Children with disaccharidase deficiency show signs of sugar malabsorption. Abdominal pain is the most common symptom, followed by diarrhea, nausea, vomiting, constipation, bloating, and gassiness [2]. Usually, children exhibit one or more symptoms soon after eating foods containing sugars. There are no specific symptoms for each enzyme deficiency. In untreated patients, chronic malabsorption of sugars can lead to malnutrition and poor weight gain.

When should I seek medical attention for my child?

Since there is no specific symptom for sugar malabsorption, disaccharidase deficiency is often under-diagnosed. If your child exhibits gastrointestinal symptoms without a clear source, it is important to seek medical attention for possible sugar malabsorption. 

How is disaccharidase deficiency diagnosed?

Several tests can be used, but analyzing samples from the small intestine is the most accurate way to diagnose disaccharidase deficiency [3, 4]. In this test, a small flexible tube with a camera and light on the end (called an endoscope) is passed through mouth into the food pipe (called the esophagus), stomach, and upper part of the small intestine to collect a tissue sample. The sample, called a biopsy, is then analyzed in a lab to measure levels of disaccharidase enzymes. 

Other tests can include a breath test, stool test, or genetic test. Symptoms also can be associated with eating certain foods. These alternative methods can be used in patients who cannot have an endoscopy. 

What is the treatment for disaccharidase deficiency?

The main treatment for disaccharidase deficiency is not eating certain foods. In children with lactase deficiency, removing or limiting lactose (dairy sugar) from the diet can help improve symptoms. In patients with sucrase deficiency/CSID, removing or limiting table sugar and starches can improve symptoms. Restricting certain foods from the diet can be challenging, so talk to your pediatric dietician for nutrition guidance. 

Enzyme replacement therapy can help patients with lactase deficiency and CSID.

Discuss these options with your child’s doctor, who can offer guidance based on your child’s specific nutrition and symptoms. 

Can disaccharidase deficiency be prevented?

Children with primary disaccharidase deficiency usually have an underlying genetic condition and are unable to make enough enzymes to digest certain sugars. This cannot be prevented, but their symptoms can be controlled with close monitoring by a healthcare team including a pediatric gastroenterologist and registered dietitian. 

However, secondary disaccharidase deficiencies are due to damage to the intestinal lining from an external cause such as infection, inflammation, or medication. Treating the underlying cause, avoiding exposures, maintaining good hygiene to prevent infections, and eating a healthy balanced diet to optimize gut health can help prevent secondary disaccharidase deficiency.

Where can I find support for my child and family?

More information on disaccharidase deficiency can be found at: https://naspghan.org/

The Congenital Sucrase-Isomaltase Deficiency Support Group is another resource for parents with children who have CSID: http://www.csidinfo.com/support.htm

References

• Nichols BL, Adams B, Roach CM, Ma CX, Baker SS. Frequency of sucrase deficiency in mucosal biopsies. J Pediatr Gastroenterol Nutr. 2012;55:S28–S30. doi: 10.1097/01.mpg.0000421405.42386.64
• Puertolas MV, Fifi AC. The role of disaccharidase deficiencies in functional abdominal pain disorders—a narrative review. Nutrients. 2018 Nov 29;10(12):1835. doi: 10.3390/nu10121835. PMID: 30501067; PMCID: PMC6315563.
• Obayo-Torres CC, Quezada-Calvillo R, Nichols BL. Disaccharide digestion: clinical and molecular aspects. Clin Gastroenterol Hepatol. 2006;4:276–287. doi: 10.1016/j.cgh.2005.12.023.
• Daileda T, Baek P, Sutter ME, Thakkar K. Disaccharidase activity in children undergoing esophagogastroduodenoscopy: A systematic review. World J Gastrointest Pharmacol Ther. 2016 May 6;7(2):283–293. doi: 10.4292/wjgpt.v7.i2.283. PMID: 27158545; PMCID: PMC4848252.

Author:  Narendra Vadlamudi, MD
Editors: Anthony Porto, MD & Amethyst Kubergov, MD
March 2024