An introduction to what is known of telomeres can be found at the Scientist: "The ends of linear chromosomes have attracted serious scientific study - and Nobel Prizes - since the early 20th century. Called telomeres, these ends serve to protect the coding DNA of the genome. When a cell's telomeres shorten to critical lengths, the cell senesces. Thus, telomeres dictate a cell's life span - unless something goes wrong. Work over the past several decades has revealed an active, though limited, mechanism for the normal enzymatic repair of telomere loss in certain proliferative cells. ... Telomeres shorten as we age. By analogy to the cellular mitotic clock, telomeres have been postulated as a marker of 'genetic age,' and telomere length has been marketed as a simple predictor of longevity. Assays of telomere length have been bundled with recommendations for lifestyle modification and for drug therapy, neither based on appropriate clinical studies. Simple but appealing arguments relating telomeres and aging are currently controversial, likely simplistic, and potentially harmful. Telomere length does indeed reflect a cell's past proliferative history and future propensity for apoptosis, senescence, and transformation. Cellular aging, however, is not equivalent to organ or organismal aging. ... Studies in humans have attempted to relate telomere length to life span. In the provocative initial publication from the University of Utah in 2003, individuals around 60 years of age who had the longest telomeres lived longer than did subjects with the shortest telomeres, but the main cause of death in the latter group was, inexplicably, infectious disease; the persons with shorter telomeres did not have a higher rate of cancer deaths. Moreover, these findings have not been confirmed in other studies of older subjects. In another study evaluating a different population, telomere length failed to predict survival, but interestingly it correlated with years of healthy life. In a Danish study of people aged 73 to 101 years, telomeres correlated with life expectancy in a simple univariate analysis, but only before the researchers corrected for age, suggesting that the correlation was driven simply by the fact that younger subjects had longer telomeres. And a Dutch study of 78-year-old men found that while telomere lengths eroded with age, they failed to correlate with mortality."

Link: http://the-scientist.com/2012/05/01/telomeres-in-disease/

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