The procedure, pioneered by a team of researchers at the U.K.’s Newcastle University, can be done a couple different ways. In the first, maternal spindle transfer, the nucleus is taken from a mother’s egg and inserted into the donor egg, which has been cleared of everything but its mitochondria. The resulting egg—which contains nuclear DNA from one woman, mitochondrial DNA from another—is then fertilized with the father’s sperm. In the second method, called pro-nuclear transfer, both the mother’s egg and the donor’s egg are fertilized; the mother’s nuclear DNA is then taken out of her egg and inserted into the donor’s, which has had its own nucleus removed.
Last week, a group of 40 researchers, bioethicists, and government advisors from around the world penned an open letter to Parliament in support of the procedure, calling it “an international demonstration of how good regulation helps medical science to advance in step with wider society.”
And on Sunday, an international collection of advocacy groups—including the U.S.-based United Mitochondrial Disease Foundation—co-authored a similar letter to British lawmakers, describing mitochondrial disease as “unimaginably cruel.” Three-person IVF, they said, “offers families the first glimmer of hope that they might be able to have a baby that will live without pain and suffering.”
On the other side of the issue are those who view three-person IVF as the first step in a slippery slope of genetic engineering. As Olga Khazan pointed out in July,
Many find the mitochondrial procedure morally questionable because of how close it seems to playing God, or Nature, or Whoever you think is in charge of making kids. Penetrating the inside of a cell and tampering with its contents is, at best, controversial, and at worst, "walking in Hitler’s footsteps," as one angry letter to the FDA put it. Some worry it's in the same sci-fi realm as "designer babies."
“There is a very clear boundary that babies cannot be genetically altered, and that once you’ve decided that you can, even for a small number of genes, you have done something very profound and then it's merely a matter of degree as to what you do next,” conservative lawmaker Jacob Rees-Mogg, who opposed the bill, told the BBC after today’s vote.
But scientists argue that the “designer baby” worries are unfounded, as mitochondrial DNA can’t really design much of anything. “It is not part of what makes us genetically who we are,” reproductive ethicist Gillian Lockwood told the BBC. “It doesn’t affect height, eye color, intelligence, musicality.”
Lockwood added that the term “three-parent baby” is a misnomer; around one-tenth of one percent of a child’s DNA would come from the donor, with the mother and father supplying the rest. "The biggest problem is that this has been described as three-parent IVF. In fact, it is 2.001-parent IVF,” she said.