SCN9A: The “jerkiest gene in the planet”?Jun 27th, 2011 | By Mary | Category: Genes
That’s not a standard that I was aware of in the past, but the article’s claims are correct–it’s certainly in the running: A single mutant gene is responsible for 30% of all mysterious pain. Well–that’s a lot of pain.
The news article refers to a scientific paper that investigated a gene called SCN9A , or in long form sodium channel, voltage-gated, type IX, alpha subunit. [note: at the Io9 story they call it SCNA9]. So what it means is that it is a sort of a pore that is moving sodium ions, and stuff may flow in or out of a cell based on how well (or badly) that pore is functioning. These types of proteins are important for helping to communicate things–like painful stimuli–so it makes sense that this gene could have a role in pain.
When I see some news like that, I go and take a look at the actual scientific paper to see what I can learn about it. The paper itself was linked in the story, and you can see it here: Gain of function NaV1.7 mutations in idiopathic small fiber neuropathy. The other title was much more compelling….But I’m not sure it’s strictly correct. From the abstract it appears that this gene was found to be present with a specific variation in some people among a rather small group who have pain (let’s note that in the same group, it wasn’t in 71.4% of them…). It’s kind of circumstantial. It’s not clear to me that the work in the paper found that it causes the pain, just that it’s in the right place at the right time to do so. And it’s a great lead–it could turn out to be causative. But I’m not sure you can say right now it is responsible for 30% of all mysterious pain.
I don’t have access to the original paper to see the details, but from the conclusion where the authors say this gene may have a “broader role” in pain of this particular type they were looking at, that seems possible. When I don’t have access to the paper, generally I’ll take a look at databases that have information on this gene from past work to see what was already known. It turns out that there are a lot of mutations in this gene with different effects.
The Online Mendelian Inheritance in Man database, or OMIM, is a well-known and venerable source of medical information on genes and disorders. I looked up SCN9A there, and it has been linked to pain in the past. They describe a family with “erythermalgia”, which you can explore more at this Wikipedia entry for it. Another issue they describe is paroxysmal extreme pain disorder–which also sounds nasty.
Interestingly, OMIM also suggests that this gene is linked to insensitivity to pain. There are some people who don’t sense pain the same way as others. That could be good news or bad news. Less pain sounds nice, right? But pain is a signal that something’s not right–and it’s important for you to pull your hand off that hot object, for example. So when this gene is knocked out of function, folks might wound themselves or be unaware of problems that need attention. I guess that’s kind of jerky too, really….
Another good place to look for information on specific genes of medical interest is called the Genetics Home Reference, or GHR. The GHR page for SCN9A is here. Their pages often give nicely written background information and medical detail, but at a more accessible level for the general public than OMIM, which is designed for professionals. GHR also has lots of links to helpful educational material if this type of information is new to you.
So yes–this may yet be the jerkiest gene around. And I hope that the new research will lead to better pain treatments for chronic sufferers. But blaming it for 30% of mysterious pain in general might be a bit premature. I appreciate the enthusiasm of science writers for cool and important results. But sometimes they give the impression we are closer to the answers than we really are, and that frustrates folks. And people with chronic pain don’t need any more frustration….