17 February 2012
By Kounteya Sinha
New Delhi India
Want to know how long you may live? A simple blood test—like the one that calculates cholesterol–—will soon offer Indians a clue to their longevity and the pace at which they are ageing.
The test, to be available in India this year, measures telomeres—protective caps at the end of chromosomes—that are the best indicators of biological age (cell age) as against chronological age. Scientists say the length of telomeres is crucial in deciding biological age—long ones indicate healthy ageing, short ones indicate some form of irreparable damage.
There is extensive scientific evidence showing the strong correlation between the percentage of short telomeres and the risk of developing diseases associated with ageing, such as cancer, cardiovascular diseases and Alzheimer’s. In turn, lifestyle habits (nutrition, obesity and exercise) are increasingly being shown to impact telomere length.
The finding that human chromosomes are protected by telomeres had won the Nobel Prize for medicine in 2009. Dr Jerry Shay, professor of cell biology at the University of Texas Southwestern Medical Center who has been instrumental in creating this blood test, told TOI during his India visit last week, “Now, more Indians believe in healthy living. Many would want to know how healthy their cells are and how long they may live. Telomeres are essential in preserving the regenerative capacity of different tissues and organs and significantly contribute to ageing when they become short. The blood test will tell the length of telomeres.” Dr Shay’s technology, known as telomapping, determines the length of telomeres of every single cell in biopsies and all tissues, such as skin. However, the test will be a costly affair, costing around $500 (Rs 23,300). According to scientists, biological age is more than important chronological age—a pointer to why some people look younger than their age.
“Telomeres act like a clock of the cell’s lifespan. Reduction in telomere length means the cell’s lifespan is shortening. Long telomeres are related to healthy ageing and overall longevity,” said Shay, who is associated with Life Length, a telomere testing company in Spain. “A short telomere represents a persistent and non–repairable damage to the cells, which is able to prevent their division or regeneration. The test will tell whether the percentage of short telomeres in a person is within normality for a given age or indicates a younger or older biological age.”
Telomeres are passed on from parent to offspring, with 23 chromosomes each from the mother and father. “At the end of each chromosome, there are around 92 telomeres. These are like plastic ends of a shoelace. As the plastic ends shred, the shoelace becomes frayed and damaged. Similarly, the shortening of our telomeres can leave our cells vulnerable to damage.”Reading The Caps
Telomeres are the protective tips of chromosomes, much like the plastic caps on shoelaces, and indicate biological age ie cell age Short telomeres are increasingly being associated with risk of developing diseases related to ageing, like cancer, heart conditions and Alzheimer’s Longer telomeres indicate healty ageing and overall longevity New blood test, at $500, will tell the length of telomeres in all kinds of cells, indicating pace and quality of ageing