What role does FUT2 play in Allergie?

FUT2 (fucosyltransferase 2) encodes an enzyme that controls the secretion of ABO blood group antigens into body fluids. This shapes the gut microbiome because certain bacteria use these sugar structures as fuel. The non-secretor phenotype (e.g., rs601338-A) is linked to altered microbiota and increased risk of Crohn's disease. For allergies, evidence is mixed: some studies report associations with higher IgE levels or allergic rhinitis, while others find no significant link. Effect sizes are small and confounded by diet, hygiene, and antibiotic use. MyBody-X DNA tests may include FUT2 variants, but their clinical utility for allergy prediction is limited. A blood test for total IgE or specific allergens is more informative. Caveat: evidence is human-moderate at best; FUT2 is not a validated allergy marker.