Myths vs facts: FTO and longevity

FTO (Fat Mass and Obesity-associated) is one of the most robustly replicated genes from GWAS for obesity. Carriers of the risk allele (e.g., rs9939609) have on average a higher BMI and a modestly increased risk for downstream conditions like type 2 diabetes. However, the direct effect on longevity is small and heavily modulated by lifestyle factors such as diet and exercise. Many direct-to-consumer (DTC) tests overstate the importance of single variants and market them as 'longevity genes' – this is misleading. The evidence for a direct lifespan-shortening effect of FTO variants is weak; instead, they act indirectly through obesity. A healthy lifestyle can largely offset the genetic disadvantage. Bottom line: FTO is a real risk factor for weight gain, but not a destiny for lifespan. These tests are not diagnostic and should not be misinterpreted as medical prognosis.