Why do some people remain healthy into exceptionally old age?
One clue may be found in a gene called FOXO3.
FOXO3 is one of the genes most consistently associated with human longevity. Studies in different populations have found that certain genetic variants in the FOXO3 region occur more often in people who live exceptionally long lives.
But FOXO3 is not a gene that simply makes someone live longer.
Its importance comes partly from what it does inside our cells.
FOXO3 is involved in the way cells respond to stress and metabolic signals, including biological processes connected with insulin and IGF-1 signaling. These systems help cells adjust their activity when conditions change.
This becomes particularly interesting as we age. Throughout life, our cells are repeatedly exposed to different forms of biological and metabolic stress. How effectively cells respond to these challenges may influence their ability to maintain normal function over time.
Scientists have studied several genetic variants within the FOXO3 region. Some of these variants appear to influence how strongly FOXO3 is expressed and how it responds under particular cellular conditions.
This may help explain why FOXO3 repeatedly appears in studies of exceptionally long-lived people.
However, there is an important limitation.
There is no single FOXO3 result that can tell someone whether they will live to 90 or 100. Several different FOXO3 variants have been associated with longevity, and each represents only one small part of the much larger genetic and biological picture.
FOXO3 therefore teaches us something more important than whether we carry a particular “longevity gene.” It suggests that the way our cells respond and adapt to stress may be one of the biological processes that contributes to healthy aging and longevity.
