Alison Motluk is a Toronto-based freelance journalist who publishes HeyReprotech, a newsletter about the ripples caused by assisted reproduction.
A flurry of papers this year have explored something known as “polygenic risk scoring.” It’s a kind of test that allows you to examine the DNA of an embryo before transferring it into a uterus, to predict what traits and conditions the person who develops will go on to have.
We’re told, for instance, that this sort of testing can make good guesses about whether a person will develop coronary artery disease, high blood pressure, certain types of cancer and other physical conditions. And we’re told that it makes sense to pick embryos that have fewer of these strikes against them. Some testing also claims to predict non-medical traits, such as eye colour and height, even intelligence.
Right now, some parents doing in vitro fertilization are using these tests to choose which embryos to transfer – which embryos to turn into their children.
Polygenic risk scoring leans on findings from a large number of “genome wide association studies,” which evaluate hundreds or thousands of tiny variations in the DNA of large groups of people. They sniff out the complex combinations that seem to predispose those people to traits or conditions we know they have. The embryo tests, dubbed PGT-P for “preimplantation genetic test for polygenic disorders,” then use those findings to make predictions.
But what if we were to look at a person toward the end of their life, and ask ourselves how valuable even an accurate prediction would have been? Take my 93-year-old father. We know exactly how that embryo turned out. What would the polygenic risk scoring of his embryo have told us about the man he would become?
To be honest, if my father’s DNA had been tested back when he was just an embryo, I’m not sure his parents would have selected him.
There was the gallbladder that had to be removed in his thirties. Serious unexplained asthma presented around age 44. He needed quadruple bypass surgery at age 63, and four stents a decade later. He has high blood pressure, high cholesterol, high blood lipids. A bum knee that needed replacing. Later, cancer.
Who’d pick an embryo like that?
In his defence, he’s 93 and counting, still alive and well. Great fun to talk to and joke around with, or to commiserate with over the state of the world.
So, despite what would probably have been an unimpressive polygenic score before birth, in a high-income country with universal health care, he did just fine. Modern medicine is remarkably effective at managing many of the things we are scoring embryos for these days. There are drugs, there are surgeries. We’re actually pretty ace at treating a lot of these things and making them go away.
Maybe polygenic scoring would have accurately predicted that he wouldn’t develop certain things: diabetes, obesity, other types of cancer. But is the absence of some bad things enough to offset the presence of others?
On the plus side, my dad was taller than average – 5 feet 11 inches – and the test might have picked that up. He is intelligent as well, and although test companies say they don’t measure that, we all know that they at least believe they can. In any case, I suspect my dad has a kind of intelligence that they’re probably not bad at measuring. He was a mechanical engineer, after all. Has a great memory. Excellent executive function.
Would intelligence make up for the coronary artery disease?
Some researchers boast that they are able to predict more elusive traits, including “creativity” and “satisfaction with life.” I’m skeptical of such claims. Still, my father does have these, so maybe they would have boosted his score a bit.
But it’s here, in the tangle of the difficult-to-measure, where I get most worried about the limits of polygenic scoring. Even though I believe strongly that genes are important determinants of who we become, I know there are some traits we can barely name, let alone characterize and find genetic underpinnings for.
And, let’s face it, if the test doesn’t search, it won’t find. So it seems to me that some of the finest human traits will go unselected while we fuss over height and blood pressure and blue eyes.
I’m thinking about my dad again. About how the characteristics are what really make the man.
Like his laugh. The way, when he finds something really, really funny, his eyes crinkle shut and he starts to cry. It’s absolutely infectious. Given a choice, wouldn’t you choose an embryo that had a really good laugh?
Or his easy connection with people. The way he can sit down on a bench, anywhere in the world, and make a buddy. He’ll hear a whole life story then retell it like a movie. What’s that trait even called? Wouldn’t you choose it for your kid, though, if you knew what it was?
Or his strength. Not physical strength, but, you know, forbearance, stoicism, bravery. How to score that?
We can unblock hearts, lower blood pressure, cut out cancers. But the really important traits may well remain unmeasurable. Integrity. Kindness. Grace. I’m not saying we shouldn’t try to reduce human suffering. I’m just saying we might be going about it the wrong way.
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