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New telomere tests do not predict when you will die, but you may still want the information

20 June 2011
By Dr Susan Kelly
Senior Research Fellow, ESRC Centre for Genomics and Society (Egenis), University of Exeter
Appeared in BioNews 612

The world of genetically predicted futures has recently been joined by a test for what is advertised as 'biological age'. The test promises to provide information about the rate at which one is ageing – and knowing when you will die would make planning for the future so much easier!

My father, a great planner, was the first person I thought of when I read about recently announced plans to offer tests that measure crucial parts of an individual’s chromosomes. A Spanish group is planning to offer such tests over the counter, at a price of around €500.

The tests measure the length of telomeres, bits of material at the ends of the  chromosome strands in our cells that protect the strands from damage, which can break down and shorten each time the cell divides. A decrease in telomere length has long been associated with cell ageing. The telomere test will identify whether an individual's telomeres are very short, a danger sign that has been associated with diseases of ageing such as cardiovascular disease and certain types of cancer.

Although telomere shortening occurs as a natural process in cells, shorter than average telomeres have been associated with various life experiences including chronic stress, smoking, and even lower educational attainment. Given that my father, a non-smoker, already has lived into his 80s without signs of any common diseases of ageing, the test is not likely to be of much use to him. For some, however, it could provide a warning sign of an underlying biological state that may lead to onset of disease. But at present the test is unable to provide the kind of predictive information that a forward-looking planner such as my father, or a life insurance company for that matter, could usefully base decisions upon.

Research over the past decade has provided evidence that shorter telomeres are associated with shorter life span. However, that does not mean that an individual's mortality can be predicted in this way. Stressful experiences, such as childhood trauma or caring for a chronically ill child, have been found to be associated with shortened telomeres. Intriguingly, research found that mice engineered to lack a telomere-lengthening chemical normally produced by the body, called telomerase, experienced premature death relative to normal mice. Injections of telomerase appeared to restore them to normal ageing patterns. To be clear, medical repair of telomeres in humans is not currently a possibility but recent research has, however, identified telomere lengthening in some individuals. This suggests some earlier damage may be ameliorated by life style and behavioural choices.

So, while the science behind the telomere test is yielding important insights into processes of biological ageing and disease, it is not currently useful as a medical tool. Rather, it straddles medicine and lifestyle advice. No medical tests are currently available or recommended for diagnosing premature ageing. Rather, finding out that one has dangerously short telomeres might serve as a wakeup call to change one's life style – quit smoking, meditate, exercise more, and perhaps be more vigilant in screening for signs of some diseases. On a less helpful note, it might also motivate a person to investigate products that claim to lengthen telomeres, reverse ageing, and so forth, opening the door to a floodgate of dubious claims.

It is important consumers who access the tests be aware of the significant limits on what the results may tell them. The tests are currently not able to predict an individual's life span, because these include a wide range of factors beyond one’s control. You would need to weigh what you may know about your family history for diseases of ageing, and any specific genetic and lifestyle risks, against knowing whether the telomeres in your white blood cells are very short.

Telomere tests join a range of genetic tests offered to consumers that seek to capitalise on people's desire to predict and control their own future. Is such a test ready to leave the research realm? If it is not ready to be used as a clinical medical test, is offering it directly to consumers a way to bypass the question of clinical usefulness? Interestingly, a similar test developed by a group in the US is currently available through research participation. Or perhaps we should merely view this test as another route through which the planners among us can gather information to factor into their decision-making.

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