Telomeres are bits of “junk DNA” at the end of chromosomes that protect your real DNA every time a cell divides. What happens is that, due to how cells divide, the very last bit of a chromosome can’t be copied 100% - a little bit gets cut off. It was thought that, as cell divide, the telomeres get shorter each time, until, they are gone. At that point, the “real DNA” cannot be copied anymore and the cell simply ages and no longer replicates.
In population level studies, researchers have shown that older people have shorter telomeres. Eventually, the cells with shorter telomeres can no longer replicate and, taken over time and lots of cells, tissue damage and the dreaded “signs of aging” can show up. Most cells can replicate about 50 times before the telomeres are too short. Some believe that telomeres are the “secret to longevity” and there are circumstances in which the telomeres will not shorten. Cancer cells, for example, don’t die (which is the main problem) because they switch on an enzyme called telomerase, which adds to the telomeres when cells divide. Some cells in your body need to do this (stem cells and sperm cells, for example) because they need to replicate more than 50 times in your lifetime
A blood test that can show how fast someone is aging - and offers the tantalizing possibility of estimating how long they have left to live - is to go on sale to the general public in UK later this year.
The controversial test measures vital structures on the tips of a person's chromosomes, called telomeres, which scientists believe are one of the most important and accurate indicators of the speed at which a person is aging.
Scientists behind the £435 test said it will tell whether a person is biologically aging, as measured by the length of their telomeres, and is older or younger than their actual chronological age, as measured by years since birth.
The scientists, however, do not yet believe they can narrow down the prediction to calculate the exact number of months and years a person has yet to live. They do not yet believe the information could be used to calculate the exact number of years a person has left to live, but several studies have indicated that individuals with shorter-thannormal telomeres are likely to die younger than those with longer telomeres.
In addition to concerns about how people will react to a test for how old they really are, some scientists are worried that telomere testing may be hijacked by unscrupulous organizations trying to peddle unproven anti-aging remedies and other fake elixirs of life.
The results of the tests might also be of interest to companies offering life-insurance policies or medical cover that depend on a person's lifetime risk of falling ill or dying prematurely.
However, there is a growing body of respectable scientific opinion that says testing the length of a person's telomeres could provide vital insights into the risk of dying prematurely from a range of age-related disorders , from cardiovascular disease to Alzheimer's and cancer.