Disaccharidase Deficiency

Synonyms

Lactase, sucrose, and maltase deficiencies

Definition

The deficiency of disaccharidases is defined as the absence of the enzymes which are located in the brush border of the small intestinal mucosa and that break down dietary carbohydrates into simple sugars so that the intestine can absorb the nutrients. The major dietary disaccharides are lactose, maltose, and sucrose. These are broken down by lactase, maltase, and the sucrase-isomaltase complex in the duodenum. A deficiency of these enzymes in the duodenum results in a range of gastrointestinal symptoms including diarrhea, abdominal pain, and bloating. Disaccharidase deficiency may be congenital or acquired (Table 1). With the exception of adult-onset lactase deficiency, hereditary disorders are rare and present at birth. They usually only affect one disaccharide and are irreversible. They include congenital sucrase-isomaltase deficiency, an autosomal-recessive disease caused by a mutation in the SI gene, glucose-galactose...