Telomeres are back in the news again, with a soon to be released publicly available test which will report your Telomere length as a ratio to your real age, crudely this could indicate your future life span.
Here’s how it works:
Telomeres are portions of DNA on the ends of your chromosomes that act as a cap for your genetic material. They are critical to the wellbeing of the cell because during cell division/reproduction (mitosis) they are protective buffers and prevent the chromosome ends becoming attached to each other or breaking up (chromosomal fraying).
Each time a cell replicates, it’s telomere shortens, eventually causing cell death when the telomere is reduced below a critical length. Human telomeres lose approximately 100 base pairs of their telomeric DNA during each cell division (mitosis), at this rate, after about 125 mitotic divisions the telomere protection would fail, causing cell death at the next division. which is why normal cells will eventually die after healthy division. Shorter telomeres imply a shorter future for a cell, effectively giving it a finite lifespan, dependant on the number of cell divisions remaining within it’s telomeres.
Cells can improve the length of their telomeres with the enzyme telomerase, which adds genetic material at the end of the telomeric DNA strand, thereby increasing the number of times it can replicate, which ultimately prolongs the life of the cell. Telomerase is not active in most cells, but is active in stem cells, germ cells, hair follicles and most cancer cells.