Sunday, March 18, 2007

The Past and Future of Red Hair

A recent issue of Science magazine included the article "Why I Have Red Hair, Need to Avoid the Sun, and Shouldn't Commit a Crime" by Ingrid Wickelgren. We have now pinpointed the gene that causes red hair. It's called MC1R, which is for a receptor on the surface of skin cells. If a mutation messes up the receptor enough that it doesn't work anymore, you have a defective MC1R gene. If you get defective MC1Rs from both your father and your mother, there's a ~90% chance that you will have red hair, pale skin, and the propensity to broil rather than bake in the sun.

So, I have a child who would have no problem being admitted to Arthur Conan Doyle's red-headed league (let's call him Red Bug). He's even got an Irish name, in the spirit of this mid-March season. His skin is pale white, so different from his older brother's that in the bath they look like two different races. So Red Bug's hair and Red Bug's skin both tell me he's probably got two bad MC1Rs, one from me and one from my wife. Sorry, kid. Still, I wouldn't trade that red mop for anything.

Furthermore, a bad MC1R also means you're at more than a three-fold higher risk for melanoma, even if you carry only one defective gene and have dark hair. Like, say, probably, me! Also, my wife (who has blond hair). What's a little uncanny about all this is that ever since I spent too long in the sun swimming in a Florida lagoon in 10th grade, I've had "redhead freckles" on my shoulders, and I also found a strange spot/mole on my arm a few years later that I never really think about except at times like this.

(The Florida lagoon story involves my adolescent brain not processing the importance of sunscreen, and the fact that That Girl Lindey was floating on a raft in the lagoon and it seemed like a good idea to make conversation for an hour or so out there. Never mind that our summer program was over a week later and I never heard from her again! I have a distinct memory of wearing a very baggy white shirt every day for the remainder of the program.)

Good thing I moved to Seattle, right? Except that the lack of sunlight in these northern latitudes could be a contributing factor to multiple sclerosis. I have a nutrition colleague who disdains all supplements except vitamin D. The reason is, we may not get enough sunlight in Seattle to convert starting materials into vitamin D, and vitamin D deficiency may be implicated in MS, and there's a surprising prevalence of MS cases around Seattle. There's enough vitamin D in milk and butter to prevent rickets, but it may not be enough to completely prevent MS.

As far as I'm concerned, this is reason enough the next time the sun comes out to take a long walking break down by the canal.

So whatever happens, we can't worry too much about increased risk, but we can all be a little more liberal with the sunscreen, especially with our little Red Bug.

My favorite part of the article is the last little throw-away bit: "Spelling out a person's MC1R genes could also help crime-scene investigators, Rees suggests. If the analysis of biological tissue left at the scene reveals two aberrant versions of MC1R alleles, there is a 90% chance that its owner has red hair."

So, little Red Bug, word to the wise: if you ever get in trouble and are tempted to deny it, just know that Daddy has access to a DNA sequencer at work and can tell if that's your tissue or not. I'm not sure if the evidence would be legally admissible, but it certainly would be sufficient for being-sent-to-your-room-until-you're-18 in the most local of courts (the one in my house).

But my little angel would never do anything like that! I do have to be careful. He does have a devious streak, especially when it comes to anything electronic with buttons. Or with wheels. Or animals.*


So, in that DNA sequencer, I have access to a powerful instrument that can scry into the past and the future, almost like something out of Harry Potter. I can see the past in the sense of where did this gene come from?, and the future in the sense of am I at a higher risk of cancer because of it?

There are certain teaching lab experiments I've had to disregard, not because of danger or cost, but because in a classroom setting there are some things you just don't want your students to find out. I mean, what would it mean to test for a genetic disorder in class? For Alzheimer's? Or paternity? Theoretically, I could do it, although with a healthy uncertainty. Ethically, I could not. Legally ... ?

The line between the "cool experiment" and the "wrong experiment" is getting very thin.

* Anyone who knows me personally and would like access to the Other Blog where I take time to chronicle everything mildly amusing these kids say, email me for an invite. But be warned -- it's like the Family Circus, only not as edgy.

1 comment:

Deanna said...

The funny thing is, Red Bug started off much darker in my recollection of him. He really became pale later, and redheaded much later. He was bald for a while, and then grew this orange fuzz.

I was curious when Ane (my daughter) was little as to whether or not she would end up redheaded, because her fuzz had a very auburn tint. But her hair has become this very medium brown as she's gotten older - though the china doll complexion has remained. I've noticed a few freckles showing up on her face recently, so I guess I'd better start breaking out the sunscreen for her. Tad? Ha! The boy is darker than I am, and he's only one-quarter Japanese!