Evidence check: FTO in the context of allergy

The association between FTO variants (e.g., rs9939609) and allergies is indirect and not robustly established. FTO is strongly linked to obesity, and excess weight increases the risk of allergic diseases such as asthma. Some studies report a link between FTO risk alleles and asthma, but this typically disappears after adjusting for body mass index (BMI). This suggests that FTO has no independent allergic effect but acts via BMI. Other allergies (hay fever, atopic dermatitis) show no consistent association. Evidence is therefore 'mixed': there are mechanistic and GWAS hints, but no confirmation from intervention studies. Direct utility of FTO testing for allergy prevention is unproven. Clinically relevant are established risk factors like family history and environmental exposures.