Does lactose intolerance result from a mutation in the gene that codes for lactase enzyme?

Yes, lactose intolerance can result from mutations in the gene that codes for the lactase enzyme, specifically the LCT gene. These mutations can lead to a decrease in lactase production after weaning, causing individuals to have difficulty digesting lactose, the sugar found in milk. In many populations, this decline in lactase production is a normal evolutionary adaptation, while in others, mutations that promote lactase persistence allow for continued digestion of lactose into adulthood.