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Bioethics board backs embryo alteration for mitochondrial disease

Reproductive procedures that would save children from inheriting mitochondrial diseases received a provisional thumbs up from an influential UK bioethics body on 12 June.

The London-based Nuffield Council on Bioethics found few ethics qualms with two procedures that involve transferring DNA from an egg cell with defunct mitochondria to another woman’s egg that has been stripped of its nucleus (see UK sets sights on gene therapy in eggs).

The procedures haven’t been tried out in humans, but basic research is under way to determine whether they are safe and effective for clinical trials to begin. Meanwhile, movement is afoot to make the procedures legal in the UK (see our recent Editorial on the process, ‘Fertile union‘).

Although independent, the Nuffield council has a history of influencing biomedical policy in the United Kingdom, and the authors of the new report hope that its input will factor into any decision to legalize the procedures.

The 100-page Nuffield report considered a number of potential ethical pitfalls of the mitochondria-swapping procedures, such as the concept of having three biological parents (two nuclear parents and the mitochondrial donor) and the possibility that endorsing mitochondrial transfers could open the floodgate for other genetic manipulations of embryos.

None of these potential objections were strong enough not to attempt mitochondrial transfers, should they prove safe and effective and if conducted as carefully monitored clinical trials, the working group that put together the report concluded. The report emphasized the importance of following the health of the children born through such procedures, and even the health of their children.

However, Geoff Watts, a science journalist and chairman of the working group, says that the report draws a fine line between mitochondrial transfers and procedures that would manipulate the nuclear genomes of embryos. Severe inherited diseases such as cystic fibrosis and Duchenne muscular dystrophy could theoretically be treated by correcting disease-causing mutations. “Such techniques would raise completely different ethical issues,” Watts said at a press briefing on 12 June.

Rather, Watts sees the debate over the ethics of mitochondrial transfers as a “dry run” for the debate that will eventually occur when gene-editing technologies mature. “It’s obvious that sooner or later someone is going to want to do this in nuclear genes,” he said at the briefing.

The report also opted not to decide how the mitochondria-swapping procedures stack up to one another, from an ethics perspective. One procedure, pro-nuclear transfer, involves the destruction of a fertilized egg, and the other, maternal spindle transfer, begins with unfertilized eggs. Shoukhrat Mitalipov, a reproductive biologist at the Oregon Health and Science University near Portland, told Nature in January that the spindle-transfer technique might be more palatable for some people.

However, Peter Braude, a reproductive biologist at King’s College London who sat on the Nuffield working group, says that safety should trump such concerns. Scientists have yet to determine whether one procedure is safer or more effective than the other. But it would be unethical, Braud says, to offer a woman a less-safe procedure in favour of assuaging qualms about embryo destruction.

Britain’s Human Fertilisation and Embryology Authority, the government body that regulates reproductive procedures and research, announced today that it will launch a public consultation on the procedures in September.

Image via Wikimedia Commons.

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    Michael Chisnall said:

    The concept of having three biological parents isn’t as novel as some people think. There are a large number of societies in South America that believe in partible paternity where more than one man is regarded as having contributed to the biological essence of the child. As far as I can see this may in fact be possible biologically. Heteropaternal twins, where the twins have different fathers despite sharing a womb, have been known about since roman times and aren’t rare. Chimerism, where two embryos fuse, also happens. Heteropaternal twinning followed by chimerism would produce an individual with two biological fathers. If chimerism is as common in humans as it is in marmosets then bipaternal individuals could be common.

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