The ACHOO gene

photic sneeze


Years ago, my mother used to hang her laundry out on the line in our backyard to dry. She wore sunglasses, even in the weak Northwest sunlight, because the sunlight made her sneeze.

It makes me sneeze too. Not every time, but often.

This is the “photic sneeze reflex.” It has a couple of other names, including (seriously) the Autosomal-dominant Compelling Helio-Ophthalmic Outburst reflex (ACHOO!), as well as the Peroutka Sneeze Reflex.

Why? I’ve read many explanations over the years. First, it was said that blue-eyed people were prone to this, because (somehow) our pale irises let more light into the eyeball, which was somehow irritating. Well, I’m blue-eyed, so fine. But my mother was brown-eyed. So let’s try again.

How about this one? When you look into bright light, your pupils contract very suddenly. The muscles which control this don’t usually work that fast or that hard, and they twitch. This feels like a tickle inside your nose, and – achoo!

This theory doesn’t hold up experimentally either, apparently.

The reflex appears to be genetic. 23andMe, the genetic-assay project which both Partner and I joined recently, tests for this, and – guess what? – I have the gene.

So it’s genetic. So what?

What else can you think of that’s genetic and caused by sudden exposure to light?

How about epilepsy?

(And this, brothers and sisters, is what genetic research is all about.)

(And – you see? – I’m a mutant after all.)


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