Lactose intolerance in infants:
Lactose intolerance is caused by mutations in the LCT gene. LCT gene provides instructions for making the lactase enzyme. Mutations that cause congenital lactase defiency interefere with the function of lactase.
In infants it is inherited in a autosomal recessive pattern, which means both copies of LCT gene in each cell have mutations. The parents of an offspring with an autosomal recessive condition each carry one copy of the mutated gene.(U.S National Institute Library of Medicine, 2010)
Mechanisms of Inheritance
Lactose intolerance in adulthood
Lactose intolerances is caused by decreasing the LCT gene's activity after infoncy. LCT gene expression is controlled by a DNA sequence located in the MCM6. Some people inherit these changes leading them to be able to digest lactase. People who don't inherit this changes have a reduced ability to digest lactase.(U.S National Institute Library of Medicine,2010)
The ability to digest lactose as you get older depends on which variations in the regulatory element within the MCM6 gene individuals had inherited from their parents. Lactase variations that promote continued lactase production are autosomal dominant, meaning that one copy of the altered regulatory element in each cell is suficient to sustain lactase production. People that haven't inherit these variations from either parents will have some degree of lactose intolerance.(U.S National Institute Library of Medicine, 2010)
Fact:
Lactose intolerance: is an autosomal recessive condition.
