Lactose intolerance: genetics of lactase polymorphisms, diagnosis and novel therapy

Lactose intolerance is a common disorder affecting an individual's ability to digest lactose present in milk or any food product. Lactose intolerance is caused by the deficiency of β-galactosidase (lactase) in the digestive tract. Diagnosis of lactose intolerance is not so simple and straightforward clinically. Many biochemical and genetic tests have been developed for the determination of lactose intolerance. Several case reports indicate wherein subjects have self-diagnosed being lactose intolerant. There is an emerging link of this disorder with human gene polymorphism, where genetic basis has been used as a diagnostic tool. The high prevalence of this condition among children and adults has compelled the production of lactose-free foods. Additionally, external enzyme supplementation has been looked at as an alternative protective mechanism in lactose intolerant subjects. This review highlights the genetic variants of lactase polymorphism and theranostic (therapeutic and diagnostic) strategies for lactose intolerance. Biomedical Reviews 2014; 25: 35-44.