Gene change triples chances of living to 100

Men who carry a particular gene variant may be up to three times more likely to live to the age of 100, according to a study published in the journal Proceedings of the National Academy of Sciences. Although other gene variants have been previously linked to longevity in animals, so-called FOXO3A is the first gene to be linked directly to longevity in humans.

In the biggest and longest study of its kind, the researchers, led by Dr Bradley Willcox of Kuakini Medical Centre in Hawaii, monitored the health of 8,000 Japanese-Americans since the mid 1960's. Focusing on five different genes, they then compared the genetic makeup of those who lived beyond the age of 95 - 213 men - to those who died before the age of 81 - 402 men - leading to the discovery that those in the older age group were leaner, had lower blood-sugar levels, lower insulin and glucose levels and were more likely to carry at least one copy of the FOXO3A gene variant. Those who inherited two copies of the gene variant - one from each parent - were three times as likely to live beyond 100, with those carrying one copy twice as likely to live to that age.

Dr Brian Willcox, who led the study, said that the findings were 'very surprising and exciting' and believes better understanding of the mechanisms of aging could have important implications for lowering risk of age-related disease and disability.

The five genes studied were selected on the basis of their role in the insulin signalling pathway - a complex network of genes which together help to regulate blood-sugar levels. It is thought that such genes are good candidates for longevity studies because problems with insulin metabolism are associated with a range of health conditions, which indirectly affect lifespan. Previous studies done on mice and nematode worms suggest that several genes involved in insulin signalling may help to protect against age-related weight-gain and cellular damage from 'free-radicals', both of which are thought to impact significantly on life span.

The next stage will be to study the effects of FOXO genes in other populations, such as Caucasians, say the researchers. Independent data from the HapMap project, a public-private effort to identify and catalogue genetic similarities and differences among different ethnic groups, has shown that the gene variant may be even more common among white and black populations than Japanese ones.