DNA From 3 Parents to Create an Embryo: A Slippery Slope?

Arthur L. Caplan, PhD


August 03, 2022

This transcript has been edited for clarity.

Hi. I'm Art Caplan, talking to you today from my home in Ridgefield, Connecticut, but I work at the NYU Division of Medical Ethics in the Grossman School of Medicine.

Recently, two countries announced that they're going to permit a very controversial procedure that's difficult, if not impossible, to do right now in the United States. Britain and Australia decided to allow mitochondrial transplant into an embryo for people who are suffering from mitochondrial diseases and wind up seeing their babies die or are having stillbirths or have no success in creating children whatsoever.

Many families know, having had a child born with a mitochondrial disease, that the mitochondrion is the little part of the cell — basically the cell battery. It's not part of the nucleus. It's outside there, but it's still genetic, inherited through the mother.

If you don't have normal mitochondria, you don't have power to drive cell division and you can't have growth. Basically, you can't have life without energy. The mitochondria supply that energy to the cells to allow the division and the splitting that is basically growth from embryo to baby to us. It's a very important entity, but it's also inherited.

If you know that you're at risk of having babies with this terrible disease, some people have succeeded in transplanting it into an egg with abnormal mitochondria — at least one suspected of being abnormal — and having a baby result. It hasn't been done many times, but Britain and Australia are convinced that this is something they should allow families with this terrible disease to use.

Much of the rest of the world is sort of balking. Why? The fear is that if you allow this kind of genetic transplant — mitochondria that's normal into an egg with abnormal mitochondria — you're going down the road to eugenics.

Pretty soon, somebody is going to say, "Well, we allowed the transfer of genetic material into an egg and that was passed on to children. Why don't we try other genetic changes, trying to make a child more immune to diseases, trying to make a child who's taller, faster" — whatever it might be that parents want. We might even see efforts to make babies born with lighter skin or with a different appearance. Maybe somebody would try to bioengineer genetic material responsible for Tay-Sachs, Down's, or other things that embryos are at risk of carrying.

Some people do argue that what makes them nervous about this situation is that there are three parents involved in having a baby. I have to say, we're way past that. We have surrogate mothers. We have people donating eggs to women who can't use their own eggs and then having their partner fertilize them.

There is this idea that three parents is going to somehow freak us out, but I'm not made nervous by adoption, and that's taking up a parental role where you have no genetic connection to the child that you might raise. This notion that transferring, if you will, the cell's battery from a donor to somebody else makes that donor a parent? I don't think so. I think that's just basically offering up something like a tendon, a bit of tissue, or a kidney. When you make a donation like that, you don't become somebody's brother or somebody's father. You just help somebody with a medical problem. I don't see three parents as an obstacle.

There is an alternative to all this genetic fiddling around. You can test embryos and see whether the mitochondria are normal from a couple at risk, but many couples don't produce any embryos except those that have risks. That isn't really a solution if you don't have the transplant option.

Now, I favor making mitochondrial transfer legal. I think it should be allowed and insurance should pay for it. It's something that I think is a real disease. The fact that it involves the genetic transfer of a tiny amount of material — the cell battery — isn't really any example of eugenics. It's trying to get a power source that works into an embryo that otherwise isn't going to make it.

To me, that's treating a disease. That's not trying to achieve a eugenic goal; it's just trying to achieve function so that somebody can have a baby. That does seem to me to be absolutely legitimate as something that medicine and healthcare can offer. It's the repair of a deficit. You're not altering the child's properties. If we don't want to go down a slippery slope where we're genetically engineering embryos for all sorts of reasons, then we can prohibit that.

Telling parents who have kids with mitochondrial diseases, with many deaths, that they can't use something that could fix it, I think the issue is risk. Does it work well? Could there be a health risk to the child? We don't know the procedure that well, so that's something parents have to decide too.

But to prohibit it and take it off the table completely, you're taking something that is aimed at disease, not enhancement, not improvement, and not some eugenic tomorrow.

I think it's time for the rest of the world to follow the lead of Britain and Australia and allow this procedure to go forward.

I'm Art Caplan at the Division of Medical Ethics at NYU Grossman School of Medicine. Thank you for watching.

Arthur L. Caplan, PhD, is director of the Division of Medical Ethics at New York University Langone Medical Center and Grossman School of Medicine. He is the author or editor of 35 books and 750 peer-reviewed articles as well as a frequent commentator in the media on bioethical issues.

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