While UK embraces life-saving germline editing, US mired in debate as promising life-saving cases go untreated


More than 16 years ago, doctors at Saint Barnabas hospital in New Jersey experimented with a new IVF technique for couples who had repeatedly lost pregnancies. Hoping to increase success rates, they transferred some of the fluid that surrounds the DNA-containing nucleus in an egg cell from a healthy donor egg. Although they didn’t know at the time why it worked, dozens of babies were born through the process.

Now, however, we do understand. The women who underwent these procedures carried debilitating genetic mutations in their mitochondria, and transferring those cellular fluids from another woman introduced healthy versions of the tiny organelles. Mitochondria are small but vital energy packs in every cell.. Most pregnancies with mitochondrial disease miscarry. When children are born, they often suffer greatly.

And then the technique was abandoned, as Devin Powell at the Washington Post explains:

In 2001, the FDA began regulating what it called “gene therapy” involving human cells. The Saint Barnabas doctors felt that this effectively prohibited them from continuing their work. (The agency has not yet given anyone permission to manipulate mitochondria in human eggs and embryos.)

But a more refined version of the procedure is coming back. Earlier this year, the UK passed legislation legalizing the use of mitochondrial donors in IVF, so that women with mitochondrial disease can have children. Why, Powell asks, can scientists in the US not even study the same techniques?


One reason is that the changes will be passed on. Mitochondrial transfer or a gene editing to cut out the disease-causing mutations both cause permanent changes to an embryo’s DNA. Those alterations will be passed on to the child, obviously. And, if that child is a woman, the edited or donated mitochondria will be passed down to her children, and so on.

This process is called germline modification. Sperm and eggs are ‘germ’ cells. Avoiding germline modification was a sort of widely accepted ethical line that researchers avoided crossing because of the generational affect. We don’t want edited genes getting into the gene pool, as Prof. Hugh McLachlan put it. And, embryos can’t give their consent for the procedure.

This year, however, a Chinese research group showed it was possible to edit the genome of human embryos, sparking an outcry for formal moratoriums on germline modification. The National Institutes of Health, White House and developers of one powerful gene editing technique have all spoken against human germline modificaiton, at least at this time.

Related article:  Podcast: Getting from one generation to the next - the life and work of pioneering embryologist Dame Anne McLaren

While many experts think crossing the germline is unethical, others argue that a moratorium itself is immoral. Even though we fear a world in which we pick out our children’s IQs, eye color and athletic ability off a menu, its hard to argue against editing out a cystic fibrosis gene, for example, in order to give a child a longer, healthier life McLachlan says:


You have to consider the ethics of acts of omission in this context. It is wrong to push someone off a cliff. But it is also sometimes wrong to fail to prevent someone from accidentally falling off a cliff. In the same way, it would surely be wrong to deliberately edit a germline so that someone who would have lived a long and healthy life will lead a short, miserable one. But what about the reverse? What if we could deliberately edit a germline to lengthen someone’s life expectancy and make them healthier? Would we not have an ethical obligation to do so? And surely if their descendants would also enjoy the same benefits, the duty to intervene becomes even stronger.

IVF and assisted reproductive techniques were morally criticized for years before they became mainstream. It’s likely public acceptance of gene editing and mitochondrial donation will follow the same torturous pat — if regulatory organizations can liberalize enough to study them. It’s now difficult to think of a situation in which we would deny potential parents access to IVF techniques (provided, of course, they can pay for them) simply because of personal moral feelings. How will we be able to deny parents access to these techniques?

Because of funding issues, Saint Barnabas had not even been able to track the 30 or so babies born using the cytoplasm transfer technique, the closest approximation we have to long term safety data for mitochondrial transfer. The originator of the research says he now has funding to publish a follow up study. If three-parent-babies prove to be safe and offer women the chance to have healthy babies, it will be hard to find the ethical justification to keep them from it.

Meredith Knight is a contributor to the human genetics section at the Genetic Literacy Project. She is a freelance science and health writer based in Austin, Texas. Follow her on twitter: @meremereknight

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