Some people are primed to live longer than others due to their genetic makeup. Nailing down such genetic factors can be cumbersome, though, but one at a time, we're getting there. The latest insight comes from researchers in Israel who've identified a genetic mutation linked to increased lifespan in men, but not in women.
The team led by Gil Atzmon, a geneticist at the University of Haifa in Israel, had some hints from previous research that height and longevity were somehow intertwined. For instance, dogs who have more insulin-like growth factor 1 (IGF-1) proteins expressed by the IGF-1 gene grew taller but lived shorter lives. Conversely, less IGF-1 led to shorter height but longer lifespan. Ponies generally outlive horses and small dogs generally outlive larger ones .'Smaller lives longer,' Atzmon says.
With this in mind, the team started to investigate in broader detail the molecules responsible for growth. The researchers sequenced the gene for growth hormone receptors in 567 Ashkenazi Jews over 60 and their children and found some individuals had a deletion in d3-GHR, a growth hormone receptor gene. The proportion of individuals carrying two copies of d3-GHR increased with age. Among the participants over age 100, the mutation was present in 12 percent or three times more common than in 70-year-old men.
Oddly, in women, the mutation was just as frequent for all age groups.
“We knew in the past that genetic paths related to growth hormone are connected to longevity and now we have discovered a specific mutation that is directly involved [in longevity], said Prof. Gil Atzmon.
When the team followed-up with investigations of long-lived populations in the United States, France and in an Amish community, thus raising the total number of participants to 841, they observed the same effect.
In 2008, Nir Barzilai, a geneticist at Albert Einstein College of Medicine and co-author of the new paper, found a mutation in another growth-related gene could extend life for women and women only. Coupled with these most recent findings, the notion unfurls that men and women have different genetic paths for longevity.
Another important finding was that the mutation that, on average, added ten extra years to their lives seemed to raise the men’s height by about an inch. This is totally opposite from what the researchers expected given their prior knowledge about lifespan and height. The relation between the two must be more complex than the scientists thought.
For now, Altzman and colleagues think the mutation amplifies the receptor's response to surges in growth hormone.
“Now our goal is to fully understand the mechanisms of the mutation and enable life extension while maintaining quality of life,” says Atzmon.
Findings appeared in Science Advances.