What role does LCT play in Allergie?

The LCT gene encodes lactase, the enzyme that breaks down lactose. Common variants (e.g., rs4988235) determine lactase persistence in adults, i.e., whether someone is likely to be lactose intolerant. Allergies are immune-mediated hypersensitivity reactions, whereas lactose intolerance is a digestive enzyme deficiency. There is no robust evidence that LCT variants directly cause or influence allergies. Confusion arises because symptoms like bloating or diarrhea after milk consumption can occur both in lactose intolerance and in cow's milk protein allergy, but the mechanisms are fundamentally different: allergy involves an immune response to milk proteins (e.g., casein), while intolerance results from lactase deficiency. Some speculative research has explored whether lactase persistence might alter the gut microbiome and thereby indirectly modulate immune function, but findings are inconsistent and insufficient for clinical guidance. In summary, LCT has no established role in allergies. Individuals experiencing symptoms after dairy should be properly evaluated for both intolerance and allergy – a genetic test alone is not diagnostic. Evidence grade: unclear, as no direct studies link LCT to allergic conditions.