An Example of Poor Correlation Between Telomere Length and Health
Telomeres are lengths of repeated DNA at the ends of chromosomes. Telomeres shorten with each cell division, and when they get too short cells self-destruct or become senescent. Thus their average length in any particular tissue, in our species at least, where other factors are less important, is a function of how often cells divide and how often the stem cells supporting that tissue deliver replacement cells with long telomeres. Telomere length is presently measured in immune cells from a blood sample, and this introduces a whole range of other influences based on the current status of the immune system. Average telomere length is fairly dynamic for any individual in response to circumstance and illness, and when measured across large populations tends to trend downwards with aging - which one might expect given the decline in both immune system and stem cell function that occurs in later life. Variation is large between individuals, however, and when looking at any specific individual it really isn't clear that measurement of telomere length is of much practical use in medicine: it is a terrible candidate for a biomarker of aging and health in that respect.
Telomeres are nucleoprotein complexes that cap the ends of linear chromosomes. Telomeric DNA decreases with age and shows considerable heterogeneity in the wider population. There is interest in the application of telomere length measures as a biomarker of general health or "biological age," and the possibility of using mean telomere length to gauge individual disease risk, and to promote lifestyle changes to improve health. This study examined the effectiveness of telomere length as a biomarker for an individual's current overall health status by assessing several measures of general health including SF-36v2 score, current smoking status and a comprehensive obesity phenotype. Participants were from the Canterbury Health, Ageing and Lifecourse (CHALICE) cohort, a New Zealand population based multidisciplinary study of aging. Telomere length measurements were obtained on DNA from 351 peripheral blood samples at age 49-51, using a quantitative polymerase chain reaction assay.
No associations were found between telomere length measured at age 49-51 and any measures of current health status. The only significant association observed was between telomere length and gender, with females having longer telomere length than men. Our results suggest that telomere length measurements are unlikely to provide information of much predictive significance for an individual's health status.