31. Lactose intolerance is not an immune response, but rather a sensitivity to dairy caused by lactase deficiency. 32. Subsequent research revealed intolerance was more common globally than lactase persistence, and that the variation was genetic. 33. Lactase is an enzyme that breaks down the disaccharide lactose to its component parts, glucose and galactose.34. Mutations which may have developed allelic variations which code for lactase production into adulthood are simply neutral mutations. 35. Additional digestive enzymes produced by these glands include dipeptidases, maltase, sucrase, lactase , and enterokinase. 36. :Only mammals have lactase , the enzyme necessary to break down lactose, in their digestive systems. 37. :: : Some human populations have developed Lactase persistence, in which lactase production continues into adulthood. 38. :: : Some human populations have developed Lactase persistence, in which lactase production continues into adulthood. 39. The changes were found by studying the sequence of DNA units near the lactase gene in nine Finnish families. 40. The lactase promoter is 150 base pairs long and is located just upstream of the site of transcription initiation.
