TRPM8: gene variant helps feel the cold
Groups of people living in cold parts of the world have had thousands of years to adapt to the climate. And adapt seems to be what they’ve done! Among other genes, there’s one that seems to particularly make a difference . It’s called TRPM8, it’s part of controlling how you feel the cold, and research from UCL’s Aida Andrés seems to show that it’s helped us evolve to live in northern latitudes. Aida spoke to Phil Sansom...
Aida - We studied a gene that encodes for a cold receptor. And what we found is that this gene has helped humans adapt to living in parts of the world where it's cold.
Phil - So this is a receptor for the cold that's in our skin?
Aida - Yeah. So it's in the nerves and it will tell your brain that it's cold.
Phil - What's the gene called?
Aida - TRPM8.
Phil - TRPM8...
Aida - Yes. So what we see in this gene is that there's a genetic variant that shows really large frequency differences between people that live in different places in the world. And this is something that is really unusual.
Phil - So if I live in, for example, Finland, I have a much higher chance of having one version of the gene; and if I live in Saudi Arabia, I guess I have a much higher chance of the other version?
Aida - Yeah, that's exactly right.
Phil - Aida, this sounds like a big pattern! Why did no one notice this before?
Aida - I think one of the reasons is that: the really striking thing about this particular gene is that you have correlations with latitude, and you really have to go after this pattern in order to see it. And when we looked at the frequencies in a map - that is when we saw the correlation with latitude. Plus, there's something else that is very interesting about this gene, and it's that this variant is not in the gene itself. It's in the regulatory part of the gene - it changes how the gene is expressed.
Phil - So if you look specifically at the TRPM8 bit, you're going to miss this change, because it's actually slightly further up the genome in the bit that's controlling which genes get actually turned into real, useful stuff?
Aida - That is correct. So the protein itself shows no differences between people in different populations. And what you have is this bit that is right before the gene, and that affects how it is expressed.
Phil - Okay, if I live somewhere northern, does my version of how this gene works - does it make me more sensitive to the cold, or less? Because I would think less, right?
Aida - So if your ancestors are from very high latitudes, you have most likely higher sensitivity to cold, actually.
Phil - I sense the cold more!
Aida - You do.
Phil - Why?
Aida - I know! I have to say, this is not very, very strong evidence, so the studies are small. But if the current studies are confirmed, I think that what tells you is that if you live in Finland... well, maybe it matters really very much if it's starting to get cold, that you notice that that's the case, and then your body can adapt, and maybe your behaviour even can adapt.
Phil - You're saying it's possible that because it's so important that we sense the cold - I mean, we don't want to die of cold - that if your ancestors came from your wintry place, then they need to be able to sense the cold really well so that they can go inside and put a fur on or something?
Aida - That's exactly right. I think that it's possible what they are telling us is that something that was not a very strong, selective pressure in some parts of the world, became a very strong, selective pressure. You really need to be able to feel the cold coming, and then you adapt to that.
Phil - Does that fit with our kind of colloquial myths of someone from a hot country coming to, I don't know, to Scotland and going, "oh my God, it's so cold here. How do you stand it?"
Aida - I think that what is happening here is that we're talking specifically only about genetic changes, right? Then on top of that, you have all of the physiological adaptations to cold temperature that people have through their lifetime. That's why we can move from one place to another and adapt also - because we're all so flexible.