SLC5A1 gene
Also known as: Monosaccharide malabsorption; Glucose malabsorption (GM)
OMIM # 606824 https://omim.org/entry/606824
1. The Disease:
Glucose-galactose malabsorption (GGM) is a very rare, potentially lethal, genetic metabolic disease characterized by impaired glucose-galactose absorption resulting in severe watery diarrhea and dehydration with onset in the neonatal period.
2. The Symptoms:
The intestinal monosaccharide transporter deficiency known as glucose/galactose malabsorption (GGM) produces a clinical picture indistinguishable from that of intestinal disaccharidase deficiency (SI deficiency – OMIM#222900). In GGM, fructose and xylose are absorbed normally. The disorder manifests itself within the first weeks of life, and the consequent severe diarrhea and dehydration are usually fatal unless glucose and galactose are eliminated from the diet. Lack of early signs or symptoms does not exclude the diagnosis.
After a normal birth, patients present with watery diarrhea on day 2 or 3 of life, soon after breast or formula feeding. The diarrhea is continuous despite normal nursing, and affected infants became dehydrated and lost weight. Other features include recurrent vomiting, distended abdomen, increased bowel sounds, acidic stool, metabolic acidosis, nephrocalcinosis, hypernatremia and hypercalcemia. Often, patients slowly develop tolerance to carbohydrates over time, although the speed and degree of improvement varies related to residual enzymatic activity.
3. Actions to take in case of early diagnosis
Infants with a positive genetic test (having 2 mutations or 2 copies of a single mutations in the SLC5A1 gene) should stop breastfeeding and be aware/ avoid milk formula containing glucose polymer or starch/ lactose-free and amino acid-based elemental formula. Early treatment, through fructose-based formula (as Galactomin19 – NutriciaÒ) or low-carb formulas as Ross carbohydrate-free formula – AbbottÒ or 3232A -Mead JohnsonÒ + fructose complementation) can solve the symptoms.
- Infants with a positive genetic test should have confirmatory GGM testing through one of the following methods:
- Identification of glucose and galactose on faecal sugar chromatography can be a useful diagnostic clue instead of the duodenal/jejunal biopsy.
- Diagnosis is now more difficult because many laboratories are no longer offering faecal sugar analysis, so a combination of genetic testing and clinical trial with fructose-based formula can be a therapeutical alternative.
- GGM is a lifelong disease that requires lifetime compliance to dietary management (glucose and galactose restriction and fructose based diet). Regular follow-up with a metabolic disease specialist, a multidisciplinary approach to care, including pediatrics, genetics and nutrition.
- Foods to avoid: all kinds of milk, butter, yogurt, cheese, and other dairy products; glucose, maltodextrin, corn syrup, lactose, and stevia; sugar (sucrose), ice cream, all desserts, candies, chocolate.
- Foods that are permitted: special formula without galactose and glucose; fructose, honey; all vegetables; all fruits; all meat, fish, and eggs; all legumes; all fat and oil; small amounts of rice, potatoes, bread, unsweetened cereal, wheat, quinoa.
- The prognosis for GGM is very favorable with lifetime compliance to fructose-based diet and balanced meals.
- Genetic counseling is highly recommended for family planning and evaluation of at-risk family members such as siblings.
4. For more information
Biblio :
- Wang W, Wang L, Ma M. Literature review on congenital glucose-galactose malabsorption from 2001 to 2019. J Paediatr Child Health. 2020;56(11):1779-1784. PMID: 32946683.
- Ma, Ming MD, RDa,∗; Long, Qi MDa; Chen, Fei RDa; Zhang, Ting MDa; Lu, Mengshan RDa; Wang, Weiyan MDb; Chen, Lihua MD, PhDb Nutrition management of congenital glucose–galactose malabsorption, Medicine: August 2019 – Volume 98 – Issue 33 – p e16828 doi: 10.1097/MD.0000000000016828.