What chromosomes are affected by lactose intolerance?

Lactose intolerance is primarily influenced by genetic variations in the LCT gene, which is located on chromosome 2. This gene encodes lactase, the enzyme responsible for breaking down lactose. Variants in regulatory regions upstream of the LCT gene, particularly in the MCM6 gene, also play a significant role in the persistence or non-persistence of lactase production. Thus, while the primary gene is on chromosome 2, the regulatory aspects involve additional genetic factors.