Is LCT useful for Allergie?

The question of whether LCT (lactase gene) is useful for allergies stems from a common confusion. LCT encodes the lactase enzyme, which digests lactose. Variants in LCT (e.g., rs4988235) determine adult lactose tolerance – a digestive condition, not an allergy. True milk allergy is immune-mediated (IgE) and involves other genes (e.g., HLA, IL-4). LCT testing is well-validated for lactose intolerance (human studies, strong evidence) but irrelevant for allergies. Consumer DNA tests often conflate the two. Anyone with allergic symptoms after milk should get an allergy test (skin prick, IgE), not a lactose gene test. Evidence for LCT in allergies is absent – this is a marketing or misinterpretation issue.