It is April 2021. Tarou Yamada is born in Tokyo, making headlines around the world. “The miracle boy,” some newspapers dub him. That’s because Tarou’s father is unable to produce sperm because of a mutation on his Y-chromosome. He is thus, in theory, completely infertile. Yet genetic tests confirm that Tarou is his son.
To make Tarou’s conception possible, a fertility clinic took stem cells from the father, corrected the Y-chromosome mutation using CRISPR genome editing and then derived sperm cells from the corrected cells. Those edited sperm cells where then used to fertilise the mother’s eggs, cementing the change into all of his nuclear DNA. In other words, Tarou Yamada is the first person whose genome has been edited.
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He will not be the last. While some countries have tightened regulations banning genome editing after the news of his birth (Japan has no such law at the moment), others have decided it is justified for purposes such as allowing infertile parents to have children that are biologically their own.
Soon there are dozens of genome-edited children being born every year, then hundreds, then thousands. These children are indistinguishable from typical children of the same age, because their genomes are entirely normal.
This is how the germline genome editing revolution is likely to begin. There is much talk about such editing of heritable DNA to prevent children getting genes for diseases such as cystic fibrosis from their parents, but almost all such diseases can already be prevented by screening IVF embryos before implantation.
Why should would-be parents opt for genome editing when pre-implantation genetic diagnosis, as it’s called, is safer and cheaper? PGD is only good for weeding out one or two harmful mutations at a time. With genome editing, it should become possible to make dozens of changes at a time. Once germline editing starts to be used for infertility, fertility clinics are likely to offer to tweak other genes at the same time. Opponents of genetic engineering will call this a slippery slope; for proponents it is sensible, even humanitarian, progress.
We all have hundreds of harmful mutations that increase our risk of cancer, Alzheimer’s, mental disorders and so on, so why not fix the worst ones if you are at it? In fact, once it can be done safely, it is arguably immoral not to.
And why stop there? There are beneficial gene variants that make people immune to HIV or less likely to become obese, for instance. Perhaps as soon as the 2030s, some countries may allow these variants to be introduced.
Such interventions would be extremely controversial. Even more so would be adding gene variants that improve personality, intelligence or other traits that we value highly. As yet we don’t know how to do that – we have yet to discover any single gene variant that makes anything like as much difference to IQ as, say, having rich parents or a good education, for example.
In fact, the brain is so complex that we may never be able to predict what effect a specific mutation has. This means introducing a brain-altering mutation that does not already occur naturally would be a huge leap in the dark, one that neither parents nor regulators should ever allow.
But genome editing can definitely make individuals less prone to all kinds of diseases. And as it starts to becomes clear that genome-edited children are on average healthier than those conceived the old-fashioned way, wealthy parents will start to opt for genome editing even if there is no pressing need for them to do so.
Will this allow the elite to give their children yet another advantage, and widen the already gaping chasm between rich and poor? Quite possibly. But let’s end with an optimistic prediction: by the time 91av’s 120th anniversary comes around, many countries will routinely and uncontroversially offer genome editing to any would-be parents who want it, on the basis that the cost of the treatment is far outweighed by the savings in healthcare costs over a person’s lifetime.
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This article appeared in print under the headline “What if… We re-engineer our DNA?”
