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Sunday, 24 April 2011

My Genes and Me

A few weeks ago Matt Ridley, the Rational (but possibly a bit over-) Optimist, wrote a blog entry condemning moves in the US to block people getting their genomes decoded. Apparently doctors over there feel that this should only be possible by going through them. There are actually strong arguments for this, as the field of Personal Genomics is still very immature, we don't understand a lot of what our DNA can tell us, and a little knowledge is a dangerous thing, particularly when placed in the hands of the health-conscious types who would go to the bother of having their genome sequenced. Nevertheless, I agreed with the thrust of his argument that it's our DNA, and we should be allowed to get it sequenced if we want to.

He was going to make a stand by getting his own DNA sequence through an American company called 23andMe, a name I've bumped into on several occasions in the last few months, in podcasts, blogs and articles. I had understood that the cost was still in the tens of thousands but, intrigued, I made my own way over to the site. Turns out that for just $199 + $60 postage I could get my genome sequenced. I couldn't resist, and ordered the testing kit. (And now I see they've reduced it to $99. Oh well, that's actually to my long term benefit, if it encourages more people to get it done.)

It arrived almost immediately, and I dutifully filled up a test tube with spit, put it into the courier pouch and sent it back. "Six to eight weeks", they said, but it was nearer three. I got the e-mail telling me the results were ready, and nervously logged into their website.

I should add at this point that they don't really sequence the whole 3 billion base pairs of your DNA: just stretches where there is useful knowledge to be gained. And even in these areas they're not looking at all possible deviations, just what are called Single Nucleotide Polymorphisms (SNPs), where a single base is altered. Despite this they have dozens of comparisons they can make, all rated according to the confidence you can have in the research behind them.

I looked at the Health Results first. These could have contained seriously bad news, but in fact there are only three conditions for which I have a substantially increased risk (other than ones where the base risk is really low to start with), and for all three there's nothing much you can do to avoid them that I wasn't already doing. The worst offender was prostrate cancer, for which a diet rich in tomatoes may be effective. Or may not. Either way, my food is going to look considerably redder from now on. I will also make sure that the doctor doesn't skip the prostrate check again when I have my annual health check up. (It may not be much fun for them, but then it's no picnic for me either.) On the plus side, they think I have a significantly reduced chance of developing Alzheimer's, which could be very useful if the retirement age keeps going up.

In the section about heritable conditions, it seems I am not a carrier for anything they can test. Good news for my son. In the section about traits they successfully managed to give me only a typical chance of having the two that I know for certain I do have. They said the same about the one medical condition I have, which does make me wonder a bit about how accurate the diagnoses are. However, part of the payment is a $5 a month subscription, so I can keep up to date with new medical advances.

Finally, I went to what turned out to be the most interesting section of all: my ancestry. They anonymously match you up with any close relatives who've also been tested, and you can make contact with any that want to be contacted. The nearest they found for me are (probable) fourth cousins, which means we share a common great-great-great-grandparent. That's quite a way back; however, as more and more people join 23andMe (no doubt tempted by the new low price), the chances of bumping into a closer relative increase accordingly.

Even more fascinating was the tracking of my paternal and maternal lines. On my father's side I seem to be descended from someone in Britain, Ireland or the Basque country. Sounds plausible enough. However, on my mother's side I can trace my line to a group made up principally of Ashkenazi Jews, Kurds and Druze. For geographical reasons I am inclined to rule out the Kurds and the Druze, so that means I am probably, and I have to admit unexpectedly, partly Jewish.

Strictly speaking, what it really means is that my mitochondria are Jewish, as they're what carry the DNA that is passed down from mother to daughter, and the mother to daughter line is only one of thousands of possible ways you can follow your family tree backwards, so the total Jewish part of my DNA might be very small. However, I find myself considerably amused by this: I was adopted as a baby, and because my birth mother was a Catholic I was entrusted to a (nominally) Catholic family. My adopted mother had converted to Catholicism when she married my father, but had been brought up a Lutheran. Her father though was partly Jewish. So all things come around.