3 August 2017

Geneticist Van Mil: “Repairing DNA does not mean we can create superbabies.”

It is on front pages all over the world today: scientists have succeeded in repairing the DNA of an embryo in such a way that a serious heart condition can be prevented. This revives an old discussion: is it actually desirable to intervene in human DNA? Lecturer of Biomedical Genetics Marc van Mil of Utrecht University and University Medical Center Utrecht considers the advantages and disadvantages.

“I understand that this is a sensitive topic,” Van Mil says. “Because in the ideal case, a man and a woman conceive a baby naturally without the need of a laboratory technician. But this could be a viable solution for carriers of genetic defects in the future.”

In the new study, published yesterday in Nature, a team of Chinese, Korean and American scientists applied the so-called CRISPR–Cas9 technique during an (artificial) insemination of an egg cell for the first time. CRISPR is kind of a pair of molecular scissors, which make it relatively simple to cut and glue DNA strains. It was already clear for a long time that in theory, countless genetic conditions could be prevented with this. Now it has actually been carried out for the first time – although the genetically modified embryos were not returned to a womb.

The question of whether or not we should actually want this is nuanced, Van Mil explains. “If a hereditary disease runs in the family right now, embryo selection can sometimes be a serious option. By means of IVF, multiple egg cells can be fertilised with sperm cells. All embryos are then inspected for the presence of the hereditary disease, after which one is implanted in the woman. The rest of the embryos are discarded.”

The new technique adds another option. The advantage: if all goes well, you need only one egg cell. Will this be the new standard in the future? “That's a discussion we'll have to have. Back when embryo selection became legal, that was the only alternative to a natural pregnancy. CRISPR now offers an additional possibility.”


This news also revives a decades-old fear: the fear of genetically modified superbabies that you can order like you pick a car. Blue eyes, a full head of hair, broad shoulders and a good brain: all cut and glued together in an afternoon.

“That's really not possible with this,” Van Mil says. “Many genetic defects have only one demonstrable location where things go wrong. That can be repaired now. But even for something as simple as the growing of hair, we wouldn't know where that is exactly. Let alone the discussion of someone's personality. On top of that: humans are more than their DNA. The collaboration between all those billions of cells in our bodies is so enormously complex. Just looking at the separate building blocks does not explain everything – it's also about the collaboration between all our cells. Compare it to a computer. Knowing what all the separate parts look like does not mean you also understand how everything works.”

On Sunday 20 August, Marc van Mil will address this topic in The Mind of the Universe tent on Lowlands (Dutch). This spring, Van Mil was pronounced national teacher of the year (Dutch).