The United Kingdom has become the first country in the world to legalize three-person in-vitro fertilization (IVF), a method of conception that combines genes from three parents.
On Tuesday, the UK’s House of Commons voted 382 to 128 in favor of the controversial technique, called mitochondrial donation, and the first “three-person baby” could be conceived later this year. Doctors say mitochondrial donation will prevent mothers from transferring incurable genetic diseases to their children. Opponents have raised ethical concerns, saying it sets humanity on the slippery slope toward “designer babies.”
Mitochondrial diseases are passed down the maternal line in families, and they are caused by mutations in a small number of genes in the mitochondria — the source of chemical energy needed for our cells to sustain life. Roughly one in 6,500 children worldwide are born with mitochondrial disease, and it causes their organs to slowly fail.
The UK’s Sharon Bernardi, who has become a high-profile proponent of the method, lost seven of her children to mitochondrial disease. Roughly 150 babies born every year in the UK with this disease could be helped with the procedure. The UK’s Public Health Minister Jane Ellison said the move was the “light at the end of a very dark tunnel” for these families.
How Mitochondrial Replacement Works
In 2013, Discover published a report on the then-pending vote, and broke down the two approaches to three-person IVF:
The first, called pronuclear transfer, is a more established procedure. It involves fertilizing a maternal egg and a donor egg with the father’s sperm in a dish, and then removing the nuclei of both embryos after one day of development (when the embryo is still a single cell). The donor embryo then contains just a cell membrane and mitochondria. The parental nucleus is implanted into this new shell and goes on developing.
The second approach, called maternal spindle transfer, occurs before fertilization… This technique removes the nucleus and other innards of the maternal egg (leaving behind the diseased mitochondria) and implants them into a donor egg, which is then fertilized with the father’s sperm.
Opponents of mitochondrial donation prefer the latter technique, since it doesn’t result in the destruction of an embryo in the process. However, religious groups and other critics still fiercely dispute the ethics behind the therapy.
A Divisive Issue
In the closing hours before Tuesday’s vote, church groups in the UK lobbied for parliament to oppose the new law. They oppose the destruction of human embryos, and worry that the law opens a Pandora’s box of genetic tinkering. Jacob Rees-Mogg, a Conservative member of parliament, expressed those concerns. According to a Guardian report, Rees-Mogg told BBC 4’s Today program:
“At the moment there is a very clear boundary that babies cannot be genetically altered and once you’ve decided that they 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.”
However, the amount of DNA coming from the third parent would represent a very small percentage of the child’s ultimate genome, others pointed out. Dr. Samuel Pang, the medical director of the Reproductive Science Center of New England, explained to the Daily Beast that “99.99 percent of genetic material comes from nuclear DNA” with only “maybe a tiny fraction of one percent” from the mitochondrial DNA.
The British government, bioethicists and research institutions all stand behind the technique. Scientific reviews from the Human Fertilisation and Embryology Authority (HFEA) determined the technique is “not unsafe,” and the Nuffield Council on Bioethics found that it was ethical, the BBC reports.
The law isn’t written in stone yet, as it still needs to gain approval from the UK House of Lords. It would likely go into effect in October. At that point, NHS doctors will work with families on a case-by-case basis to determine if they are eligible for the treatment.
Now that the UK has taken a bold step in favor of science, more countries around the world could grow amenable to the procedure. Currently, the US Food and Drug Administration bans mitochondrial donation in the US.
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