What is Disaccharidase Deficiency?

Disaccharidase Deficiency
A model for GI disease in children with autism. A) Schematic representation of enterocyte-mediated digestion of disaccharides and transport of monosaccharides in the small intestine. Disaccharidases (SI, MGAM, and LCT) in the enterocyte brush border break down disaccharides into their component monosaccharides. The monosaccharides, glucose and galactose, are transported from the small intestinal lumen into enterocytes by the sodium-dependent transporter SGLT1. On the basolateral enterocyte membrane, GLUT2, transports glucose, galactose, and fructose out of enterocytes and into the circulation. The expression levels of disaccharidases and hexose transporters may be controlled, in part, by the transcription factor CDX2. B) In the normal small intestine, where expression of disaccharidases and hexose transporters are high, nearly all disaccharides are efficiently digested and monosaccharides are absorbed from the lumen. C) In the AUT-GI intestine, where expression of disaccharidases and hexose transporters are deficient, mono- and disaccharides accumulate in the lumen of the ileum and cecum resulting in dysbiosis, diarrhea, bloating, and flatulence. Impaired carbohydrate digestion and transport and mucosal dysbiosis in the intestines of children with autism and gastrointestinal disturbances. Williams BL, Hornig M, Buie T, Bauman ML, Cho Paik M, Wick I, Bennett A, Jabado O, Hirschberg DL, Lipkin WI - PloS one (2011). Not Altered. CC.

Disaccharidase deficiency involves decreased hydrolysis of the disaccharides double-sugars by the disaccharidase enzymes lactase; maltase-glucoamylase; sucrase-isomaltase; palatinase and trehalase. 

What is the Pathology of Disaccharidase Deficiency?

The pathology of disaccharidase deficiency is:

-Etiology: The cause of disaccharidase deficiency is autoimmune disorder that is triggered by hypersensitivity to ingested gliadins from wheat and other cereals, due to genetic variations.

-Genes involved: Unknown.

-Pathogenesis: The sequence of events that lead to disaccharidase deficiency are: A deficiency of an intestinal disaccharidase prevents hydrolysis of ingested substrate, a disaccharide. The osmotic load of the unabsorbed disaccharide causes secretion of fluid and electrolytes until osmotic equilibrium is reached. Dilation of the intestine caused by the osmosis induces an acceleration of small intestinal transit, which increases the degree of maldigestion.

-Histology: The histology associated with disaccharidase deficiency shows reactive epithelial changes in distal end of small intestine.

How does Disaccharidase Deficiency Present?

Patients with disaccharidase deficiency typically in all genders present at any age. The symptoms, features, and clinical findings associated with disaccharidase deficiency include: abdominal pain, bloating, and flatulence. A less common but still frequent symptom is diarrhea.

How is Disaccharidase Deficiency Diagnosed?

Disaccharidase deficiency is diagnosed by biopsies during upper endoscopy, direct assessment of enzyme activity spectrophotometry, fluorescence, and radiolabeling.

How is Disaccharidase Deficiency Treated?

Disaccharidase deficiency is treated by complete dietary elimination of the symptom causing disaccharidase is curative, enzyme supplementation for specific enzyme.

What is the Prognosis of Disaccharidase Deficiency?

The prognosis of disaccharidase deficiency is good. Most patients have a considerable improvement in signs and symptoms with dietary modification alone.

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Last updated on May 25, 2022