Biology / Genetics / Health / Science

Mutants are taking over

Nah, I’m not commenting on the X-Men. There’s been a little pulse of articles about a particular new study, with a couple getting a bit het up about the ubiquity of cancer the data suggests. Hold on, I’m not going to tell you the stats yet, because I think it’s causing a few unnecessary twinges of worry. Let’s get armed with information first!

As is often the case with science news, the real truth is that we kinda knew what the outcome of the study would be already: this is just more data on the extent of it. It’s almost certain that you and I contain mutated cells, with DNA that is not identical to the original first cell formed by the fusion of our parents’ gametes. And this isn’t just on the level of epigenetics, tissue differentiation, etc. I mean that you very likely have mutated cells where the DNA is damaged, where the proteins produced by the cells are misshapen, and very likely even cells that have changes normally associated with cancer.

This is not news. This is not an alarming new thing about the modern world, even. All beings on Earth, to some degree or another, have this problem. Earth is full of challenges for DNA: there are chemicals that cause mutation, natural sources of radiation, and errors in your own copying software. Life is, in fact, extremely robust to this. It’s very rare indeed for a single mutation to cause a deleterious effect on its own, both because your cells have some power to repair DNA and because there are other backup systems — not least the fact that the cell next door probably does not have the same mutation. It can produce the protein correctly.

It usually takes multiple mutations to the same cell to cause cancer, along with a dollop of chance. And that’s what this study really demonstrates for me. Yizhak et al used RNA to figure out what cells in a given tissue were mutated. The mutated DNA creates non-standard RNAs, which were picked up by sequencing. They found that 95% of healthy people had patches of mutated cells in the organs examined (including the skin, kidneys and liver, for just three examples). That sounds worrying, but it shouldn’t be — those people were in good health, and despite the mutations, are not clinically riddled with cancer. Presumably some of these people will go on to develop cancer, and it may even arise from those already-mutated cells, but right now those cells are in balance with their other cells and their tissues are still doing their job. It will probably take several more mutations of just the right (or wrong) kind in order for those cells to become cancerous.

It sounds scary that our bodies harbour cells which may later go rogue, but it’s really only to be expected. Have faith in the body’s back-up systems! For all that cancer seems very common and very scary to us now, evolution has by necessity left complex life equipped with safeguards against cancer, and those mutated patches of cells in healthy tissue prove that it works. It’s probably working for you and me right now.

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