After years of debate, the British House of Commons approved the creation of embryos with genetic material from two women and one man by a vote of 382 to 128. The House of Lords will probably pass the bill, which amends the 2008 Human Fertilisation and Embryology Act, later this year.
The technique is so controversial that even its name is a matter of dispute. Supporters describe it as “mitochondrial transfer”; opponents and the media call it “three-parent embyros”. There are two approaches, one beginning with a woman’s eggs and the other with an embryo. But both transfer the nucleus of a cell with faulty mitochondria floating in its cytoplasm into a cell with healthy mitochondria from a second woman.
The headline in Nature News summed up the significance of the vote: “Scientists cheer vote to allow three-person embryos: British decision could be a watershed to approving mitochondrial replacement technique in other countries”. Britain is the first country in the world to allow mitochondrial transfer, which has been banned elsewhere because it alters the human germline and could be described as “genetic engineering”. The Food and Drug Administration in the US is currently studying the issue. If it were to green-light the technique, it could rapidly spread elsewhere.
"It's great news for the patients with mitochondrial disease. It gives them real hopes and that's just fantastic,” commented Doug Turnbull, a neurologist at Newcastle University, who has been prominent in lobbying for a change in the legislation.
The technique is meant to help families whose children would otherwise live with a mitochondrial disease. These vary greatly in severity, but at their worst the children suffer from diseased organs, gastrointestinal disorders, respiratory disorders, neurological problems, autonomic dysfunction and dementia. There are various estimates of how many families would be helped by the IVF technique. Nature News said that 2,000 women would benefit, based on a recent letter in the New England Journal of Medicine. However, the letter said that there would only be 152 women affected each year. Of these, perhaps 10 or 20 might take advantage of it.
Prof Alison Murdoch, one of the technique’s pioneers, said: “This is good news for progressive medicine. In a challenging moral field, it has taken scientific advances into the clinic to meet a great clinical need and Britain has showed the world how it should be done.”
How was it done? How did British scientists manage to persuade Parliament to overcome the “moral challenges” and to accept “progressive medicine” which its opponents described ominously as genetic engineering, three-parent babies, and eugenics? There appear to be four elements in their lobbying strategy.
Advance planning: a number of scientific, ethical and public consultations have been carried out since 2011, with the enthusiastic backing of scientific and government organisations.
Highlighting the suffering of the children and their parents. Some affected families have had very tragic experiences. One woman, Sharon Bernardi, lost all seven of her children to mitochondrial disease.
Framing the technique as a cure for children. In the media, mitochondrial transfer was consistently described as a cure for dread diseases. In fact, not one child will be cured; instead, healthy IVF children will be created. The editor of the Journal of Medical Ethics, Julian Savulescu, phrased it very carefully in an article for the Guardian: “Importantly, by doing this transplant at the very early stage of embryo development, the disease is cured. The children of the offspring of this procedure will themselves be free of mitochondrial disease. It would be eradicated forever in this family.” But in a video directed at members of Parliament, he said, less cautiously, “every year 150 children are born with this condition and you have the power to cure them.”
Defining the human person as nuclear DNA. Mitochondrial DNA constitutes only 0.054 per cent of the total DNA in a cell, according to Dame Sally Davies, Chief Medical Officer for England, who played an important role in the debate. It is the DNA in the nucleus “which determines our personal characteristics and traits such as personality, hair and eye colour”. This was repeated over and over by supportive scientists: mitochondrial DNA is just a battery pack. No one explained how mitochondrial DNA could be both a negligible part of the human person and could also have devastating effect upon a child’s organs, systems and personality.
Redefining genetic engineering. Instead of defining genetic engineering as modification of the genome, scientists spoke of it as modification only of nuclear DNA. The mitochondrial DNA was simply a replaceable module or an interchangeable spare part. In one of the cleverest redefinitions, Stephen Wilkinson, a bioethicist at Lancaster University, “mitochondrial replacement isn’t genetic modification as such, but rather donation … nothing really new is being added to the human gene pool.” In other words, genetic engineering only happens if an artificial or non-human gene is added to the embryo.
Not all scientists welcomed the decision. Paul Knoepfler, of UC Davis School of Medicine, and a leading American stem cell researcher, thought that legalisation was premature:
“There is no doubt that mitochondrial diseases are truly terrible and need to be addressed, but if the potential outcomes from the technology are still vague, there are safety concerns, and it raises profound ethical issues such as changing the human genome heritably as is the case here, then my view is that a careful approach is both practical and logical. We cannot at this time have a reasonable expectation that this technology would be safe and effective. That may change in coming years with new knowledge. I hope so.
“As strange as it may sound, although mitochondria have been studied for around 150 years, they remain in many ways still a new frontier for science with many mysteries. We are only now, for example, starting to understand how the mitochondrial genome works. There was just recently a very unexpected discovery that the mitochondrial genome produces thousands of potentially powerful non-coding RNAs with largely unknown functions. Nobody has any clue how these RNAs might behave in the context of mitochondrial transfer.”