Some people develop soft little balls of fat under the skin, called lipomas. They are not dangerous, but sometimes there are a lot of them. For a long time, no one understood why.
Scientists compared the genomes of 13 526 people with lipomas and nearly half a million without them. They found stretches of DNA that showed up more often in people with lipomas. These stretches are linked to genes that make telomeres longer. Then they checked: people who are born with longer telomeres really do tend to have lipomas more often.
Long telomeres let cells keep dividing longer. That is useful for renewing tissues, but every extra opportunity to divide comes at a price: a cell may start growing out of control. For a lipoma that is not dangerous, but the principle itself matters. If drugs that lengthen telomeres come along in the future, they may have this kind of side effect.
In a series of 188 tumors, only one of 58 lipomas from patients with multiple lipomas had detectable chromosomal changes, which led scientists to suspect a hereditary predisposition as early as 1988.
In Neal Stephenson's novel The Diamond Age, genetic manipulations of telomeres are used to extend life but lead to unforeseen consequences. This work shows that telomere elongation may come at a price in the form of increased tumor risk, albeit benign ones.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.