Telomere basics and why you should measure them with TeloMe

Telomeres are the protective DNA structures at the ends of chromosomes. There is a large degree of natural variation in telomere length—some people have long telomeres and some have very short ones, even at a young age. In general, as one gets older telomeres shorten and degrade, and the overall length distribution becomes increasingly heterogeneous. Many research publications over the past two decades have shown that shortening telomere length is an indicator of declining function with age.

A 2013 report in the Journal of the American Medical Association was widely reported in the media because it showed that short average telomere length indicates susceptibility to and severity of the common cold—even in people as early as their twenties [1]. In March 2013, an international team of scientists published a report showing that short average telomere length is associated with a higher risk of mortality and age-related diseases. The team measured telomere lengths in over 48,000 individuals and followed their health. They identified seven genetic variants, each of which is associated with a reduction of average telomere length by the equivalent of 2 to 4 years per variant and increased risk of age-related disease [2].

However, there are some substantial caveats to consider when assessing these studies and any other information relevant to telomere length:

• 1) The technologies used in these studies (and the vast majority of other recent links between telomeres and health) measure only average telomere length. This results in the grouping together of people who have very different telomere length distributions, including in the shorter range. Shorter telomeres might be more important determinants of function than average, so measuring average alone can be uninformative or even misleading [3].


• 2) Other large-scale and high-quality studies using these same technologies for measuring average telomere length have produced contradictory results (for example see [4][5][6]).


• 3) Recent studies also show that telomere length is not fixed and can be altered through various interventions. However, initial reports suggest that these approaches can shift the overall average length and proportion of short telomeres, and indicators of health, in a counterintuitive manner. For example, telomerase activation is thought to preserve cells and their functions, and published reports show that telomerase activation therapy in experimental animals improves measures of overall health [7]. Preliminary reports in people show similar outcomes [8]. However, telomerase activated in this manner works preferentially on very short telomeres and one result is that the relative proportion of short telomeres is increased. This increase causes average length to go down in many subjects. In other words, health appears to improve even though average telomere length goes down and proportion of short telomeres goes up.

These results challenge the idea that shorter average telomere length is always bad, and highlights that the complexities of telomere dynamics and their effects on health are still not well understood, especially in people. Nevertheless, it also shows that measuring more than just the average telomere length can provide essential information that should eventually allow us to understand the role of telomeres in health.

The simple fact is that much remains unknown about telomere length and possible effects and influences on health. The most informative current course of action for individuals and science generally is for many people to track the lengths of their telomeres over time using superior technologies that allow measurement of more than average length. TeloMe's superior technologies provide more information than just average telomere length, and will help advance the field past these many uncertainties.

REFERENCES

[1] Association between telomere length and experimentally induced upper respiratory viral infection in healthy adults. Cohen S, Janicki-Deverts D, Turner RB, Casselbrant ML, Li-Korotky HS, Epel ES, Doyle WJ. Journal of the American Medical Association (JAMA), 2013 Feb 20;309(7):699-705.
[2]Identification of seven loci affecting mean telomere length and their association with disease. Nature Genetics, 45, 422–427, Published online 27 March 2013.
[3] The shortest telomere, not average telomere length, is critical for cell viability and chromosome stability. Cell, 2001 Oct 5;107(1):67-77. Hemann MT, Strong MA, Hao LY, Greider CW.
[4] Telomere length in white blood cells is not associated with morbidity or mortality in the oldest old: a population-based study. Martin-Ruiz CM, Gussekloo J, van Heemst D, von Zglinicki T, Westendorp RG.
Aging Cell. 2005 Dec;4(6):287-90. PMID: 16300480
[5] Association between telomere length, specific causes of death, and years of healthy life in health, aging, and body composition, a population-based cohort study. Njajou OT, Hsueh WC, Blackburn EH, Newman AB, Wu SH, Li R, Simonsick EM, Harris TM, Cummings SR, Cawthon RM; Health ABC study. J Gerontol A Biol Sci Med Sci. 2009 Aug;64(8):860-4. PMID: 19435951
[6] No association between telomere length and survival among the elderly and oldest old. Bischoff C, Petersen HC, Graakjaer J, Andersen-Ranberg K, Vaupel JW, Bohr VA, Kølvraa S, Christensen K. Epidemiology. 2006 Mar;17(2):190-4. PMID: 16477260
[7] The telomerase activator TA-65 elongates short telomeres and increases health span of adult/old mice without increasing cancer incidence. Bernardes de Jesus B, Schneeberger K, Vera E, Tejera A, Harley CB, Blasco MA. Aging Cell, 2011 Aug;10(4):604-21. Epub 2011 Apr 14.
[8] A natural product telomerase activator as part of a health maintenance program. Harley CB, Liu W, Blasco M, Vera E, Andrews WH, Briggs LA, Raffaele JM. Rejuvenation Research 2011 Feb;14(1):45-56. PMID: 20822369