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Q&A: Are designer babies our brave new future? A geneticist explains what’s at stake

Q&A: Are designer babies our brave new future? A geneticist explains what’s at stake

Picture of Alexandra Demetriou

Last November, Chinese scientist Dr. He Jiankui announced the birth of the first two genetically modified humans — twin girls named Nana and Lulu, whom he helped create using gene editing technology. This method of “gene surgery,” as he described it in his announcement on YouTube, is widely used in research and certain clinical settings around the world. But ethical concerns have kept scientists from using the technique to create living, breathing, genetically modified humans — until now.

The technology He used is called CRISPR, which can be thought of as a find-and-replace tool on your computer: It searches through the entire genome and helps researchers modify DNA at specific locations through gene-editing proteins. Dr. He intended to introduce a genetic change that would make the children resistant to HIV, though other scientists have yet to verify whether or not this change worked, or worked safely. He’s controversial experiment triggered outrage in the genetics community and led to leaders in the field calling for a moratorium on germline editing, or creating DNA edits that will be passed on to an individual’s descendants.

I recently spoke to Dr. Mazhar Adli, a researcher at the University of Virginia whose laboratory utilizes and develops CRISPR-based gene editing techniques. We discussed the ethics and the future of genome editing now that the first genetically modified babies have arrived. The following interview has been edited for clarity and brevity. 

Alexandra Demetriou: The current controversy is about putting a moratorium on what scientists call “germline editing.” Can you explain how germline editing is different from somatic gene editing, in which scientists edit cells not involved in reproduction?

Mazhar Adli: The difference between germline and somatic cell editing is that when you edit somatic cells, any change you make stays just with that individual and will not be passed on to the next generation. However, if you do germline editing, that means that every cell in that body is going to be edited, including the germ cells which transfer that genetic material to the next generation. Therefore you are not only changing that person, you are also changing any offspring from that individual, and since it is a genetic change it will go forever. That is the biggest ethical dilemma: You are changing something in an embryo, which can’t give consent, and you are also changing any offspring that will oneday come from that embryo. It has much larger-scale implications.

AD: Back in 2017 there was a big story in the news where an American doctor edited out a human heart defect in embryos. Is that a similar situation? 

MA: It is a similar situation, but the American doctor did it solely as an experiment and didn’t let that embryo develop into a baby. Dr. He, on the other hand, implanted edited embryos into the mother’s womb, and those embryos developed into babies that were born. So that’s the big difference — stem cell research and embryonic research is allowed in the U.S. as long as you don’t implant the embryo.

AD: What kind of health risks could those gene-edited babies then face in their adult life?

MA: The short answer is that we don’t know. We have no idea what’s going to happen to these babies once they develop into adulthood, because we have never done these experiments before. It’s completely unknown to us. That’s the scary part, right? Because let’s say there are major side effects. Who is going to take responsibility? Is it going to be the parents? Is it going to be the scientist who’s done it? And beyond that, what can you do about it once that person has grown up and is suffering from a side effect you caused?

Dr. Mazhar Adli
But let’s assume the children turn out healthy. You’re now opening Pandora’s box, because you could then basically start designing humans, and there are two roads you could go down. One is that you can correct disease-relevant mutations, which is something a lot of scientists are supporting. There are 6,000 genetic diseases that can be potentially cured with gene editing. But on the other hand, people could go down the enhancement road and start designing babies with more muscle, or who are taller and have a certain eye color, that sort of thing. And that’s the scary part. Because throughout history we’ve seen eugenics movements, and it’s possible that a political entity or government could try to use such a technology to design a new human race. So CRISPR becomes a scary tool when you start editing humans. 


AD: Do scientists actually know enough to make these designer babies now, or is that still far beyond today’s scientific knowledge?

MA: Certain things could be designed based on current knowledge, but there are many other biological traits that we can’t really pinpoint to a single gene and will take much longer to fully understand. For example, based on animal models we’ve found some of the genes that control simpler traits, like cholesterol levels or height. But there are certain biological traits that are more complicated, like IQ level. We’re still figuring out which genes, and how many different genes, contribute to complex traits like that. But a trait like muscle, for example, is much simpler and we could manipulate those genes to make an individual more or less muscular. Dr. He has basically created a designer baby. He manipulated a gene to make those individuals less susceptible to HIV virus infection. The trait is relatively simple, but he still is designing something.

AD: Do you think it’s inevitable that we will start to see more designer babies like this, if the technology is proven safe enough?

MA: Yes, I think it is inevitable. Our generation is going to see genetically modified humans walking around us. Indeed, there are basically already genetically edited humans walking among us. Take, for example, the three-parent babies that come from mitochondrial transplantation. There are many such cases, and these humans are healthy and walking among us. The United States initially allowed mitochondrial transplantation, but later banned it. But in 2016 for example, an American couple that wanted mitochondrial replacement therapy just flew their U.S. doctor to Mexico and had the operation done there instead. So in a way, once you have these opportunities, you cannot fully close the door on them.

AD: So the only way to prevent it would be an international law, right?

MA: An international law that can be enforced and supported by a government-level agreement on these things. If it’s not enforced, it’s only going to be some media statement from scientists. Currently, almost all scientists agree that we shouldn’t be trying to create designer babies. But if there’s even one rogue scientist who decides to do it, and there is no institution or political entity that can enforce the laws, then how can we prevent it from happening?

AD: Current scientists are proposing a moratorium on genetically editing germline cells. Do you think it will be beneficial or do you think it might impede research in the long run?

MA: We need to carefully frame the moratorium so the research and development aspect is not affected, and only germline editing is prevented. And I think the public and the media really need to be engaged in this discussion. This is an impressive technology that has the potential to help cure many genetic diseases, so we should be very careful to not pump fear into the public because if this happens, there will then be a general lack of societal acceptance.

I liken this to the rise of in vitro fertilization. The first IVF baby was born in 1978, and initially it was all over the headlines and there was a big fear that doctors and scientists were creating some kind of monster. But now IVF is a routine thing — there are 18-20 million babies born through IVF walking among us — and the public has accepted it. I think genome editing probably will have a similar thing that many babies will hopefully be cured through genome editing. But we must move forward carefully and engage the public in the ethical debate.

Correction: An earlier version of this post incorrectly stated that Dr. Adli is a researcher at the University of North Carolina at Chapel Hill. Adli obtained his Ph.D. there but is now at the University of Virginia.


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