Why short telomeres cause senescence has been mostly worked out. A very short telomere will lose its histone packaging, and, like a shoelace that’s lost an aglet, the DNA at the end of the chromosome becomes exposed. The cell detects the DNA end and thinks it’s a DNA break. It goes to work to try to repair the DNA end, sometimes fusing two ends of different chromosomes together, which leads to hypergenome instability as chromosomes are shredded during cell division and fused again, over and over, potentially becoming a cancer.
Short explanation of telomeric length
