What are the most common variants associated with lactose digestion?

The ability to digest lactose into adulthood is most commonly associated with genetic variation in the MCM6 gene. The MCM6 gene encodes a protein that controls the production of other proteins, including lactase, which is required for lactose digestion.

There are five common variants in the MCM6 gene that enable the lifelong production of lactase and therefore reduce the likelihood of lactose intolerance.