Lactase deficiency, congenital


What is congenital lactase deficiency?

Congenital lactase deficiency is a rare genetic disorder. Infants with this disorder lack an enzyme called lactase. This enzyme has a job. That job is to breakdown lactose in the body. Lactose is a sugar and is found in milk and milk products. It is used by the body for fuel. Infants with congenital lactase deficiency cannot absorb and digest lactose. Infants will have severe, watery diarrhea. Without treatment, they may become dehydrated, lose weight and experience malnutrition. Symptoms usually start during the first week of life when an infant is given breast milk or formula (which will contain lactose) for the first time. Infants are treated with special formulas that do not contain lactose. This will allow for normal growth and development. Congenital lactase deficiency is caused by specific changes in a gene called LCT; people have no or very little activity of the lactase enzyme. Congenital lactase deficiency can be a severe disorder if left untreated. Congenital lactase deficiency is related to, but different from, lactose intolerance common in adults. Lactose intolerance involves the same enzyme, lactase, and the same gene, LCT. However, in lactose intolerance there is a gradual decline in lactase that makes people intolerant of milk and milk-containing products as they grow older.

SOURCE: Emory University - Department of Human Genetics in collaboration with ThinkGenetic • • DATE UPDATED: 2016-05-31


Lactose Intolerance. Genetic Home Reference website.

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