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Chromosome Ends In Elderly Could Show Mortality Risks
Lancet
01/30/2003
By Harvey McConnell
Measuring the ends of chromosomes (telomeres) among older men and women could indicate their relative risks of dying from age-related diseases.
Dr Richard Cawthon and colleagues at the Department of Human Genetics, University of Utah, Salt Lake City, United States, said their findings are "the first research study showing that telomere length is predictive of survival in humans. It supports the hypothesis that telomere shortening is a fundamental process of ageing, contributing to mortality from multiple age-related diseases."
They point out that there is a gradual loss of telomeric DNA in dividing somatic cells as people age, and this could contribute to replicate senescence, apoptosis, or neoplastic transformation. In the genetic disorder dyskeratosis congenita, for example, telomere shortening is accelerated, and patients have premature onset of many age-related diseases and early death.
In the general population, however, whether people with longer telomeres live longer than those with shorter telomeres has not been tested before now.
The researchers studied 143 men and women over the age of 60. When the study population were matched by age, and ranked by telomere length, done by blood DNA assessment, those in the top half for telomere length lived four to five years longer than those in the bottom half.
People with shorter telomeres were found to have higher mortality rates. This was associated with a 3.18-fold increase in risk of death from heart disease for those in the bottom half of telomere length, to an 8.54-fold increased risk of death from infectious diseases for people in the bottom quartile of telomere length.
"Our results lend support to the hypothesis that telomere shortening contributes to the rise in mortality rates from multiple diseases typically seen with aging, " Dr Cawthon and colleagues said, "Alternatively, telomere shortening might not affect mortality, but might be controlled by (and so serve as a useful indicator of) progression of a process of senescence that raises mortality rates by other mechanisms."
They conclude that if telomere shortening is a fundamental process of ageing, " then it may be possible to extend the duration of healthy adult life using medical interventions that maintain telomere length."
Lancet 2003;361:393-95.
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