Some people may be genetically programmed to age at a faster rate, according to new research. Scientists have identified a genetic variant linked to the length of telomeres--a region of repetitive DNA that caps the chromosomes. Previous research has shown that telomeres shorten with age and are considered a marker of biological aging. The research was published this week in the journal Nature Genetics.

Other scientists have identified genetic variants that appear linked to healthy aging and longevity, including a variation that causes people to produce less of a protein called cholesterol ester transfer protein (CETP). These people have higher levels of so-called good cholesterol or high-density lipoprotein (HDL), as well as better cognitive function in old age and lower risk of Alzheimer's.

In the new study,

"what we found was that those individuals carrying a particular genetic variant had shorter telomeres i.e. looked biologically older," said Nilesh Samani, of the University of Leicester of the Department of Cardiovascular Sciences, who co-led the project, in a statement. "Given the association of shorter telomeres with age-associated diseases, the finding raises the question whether individuals carrying the variant are at greater risk of developing such diseases."

"The variants identified lies near a gene called TERC which is already known to play an important role in maintaining telomere length," added Tim Spector from King's College London and director of the TwinsUK study, and co-leader of the project. "What our study suggests is that some people are genetically programmed to age at a faster rate. The effect was quite considerable in those with the variant, equivalent to between 3-4 years of 'biological aging" as measured by telomere length loss. Alternatively genetically susceptible people may age even faster when exposed to proven 'bad' environments for telomeres like smoking, obesity or lack of exercise - and end up several years biologically older or succumbing to more age-related diseases. "

Two long-lived species of bats appear to have proteins that are especially resistant to stress, which may explain why they can outlive many other similar-sized mammals.

According to a press release from the FASEB Journal:

[Asish Chaudhuri, a biochemist at the VA Medical Center, in San Antonio] and colleagues made their discovery by extracting proteins from the livers of two long-lived bat species (Tadarida brasiliensis and Myotis velifer) and young adult mice and exposed them to chemicals known to cause protein misfolding. After examining the proteins, the scientists found that the bat proteins exhibited less damage than those of the mice, indicating that bats have a mechanism for maintaining proper structure under extreme stress.

Previous research covered by Technology Review suggested a similar characteristic underlying the lengthy life span of the naked mole rat, a rodent that can live for up to 30 years, compared to about 3 or 4 years for the average mouse.

The analyses showed that proteins in mole-rat cells are more resistant to unfolding, making them more stable than those of mice. The researchers also found evidence that the cells of mole rats have more efficient mechanisms for getting rid of improperly folded or oxidized proteins . . . The results suggest that naked mole rats can withstand oxidative damage better by keeping their proteins stable and quickly removing unfolded proteins before they can accumulate.