A new twist on a fertility procedure allowed three people to contribute DNA to a healthy boy born to a Jordanian couple on April 6.
While the child is actually not the world’s “first three-person baby,” as many news outlets have reported, he is the first healthy baby born using a new technique that doesn’t require the destruction of an embryo, according to New Scientist.
As Buzzfeed reported, dozens of so-called three-person babies have been born since the 1990s. The three-parent method is tried when a parent does not want to pass down a genetic mutation; in this case, the boy’s mother carries the genetic mutation for Leigh syndrome, a rare neurological disorder that affects the central nervous syndrome.
How it worked
The genes for Leigh syndrome live in the cell’s mitochondria, which surround the cell nucleus. Dr. John Zhang and his team from the New Hope Fertility Center in New York City took only the mother’s nucleus -– the part that carries her normal DNA -– and implanted it into a donor egg that had already had its nucleus removed. Thus, the new egg carried only the healthy DNA from both women. All the destructive genetic materials in the mother’s mitochondria were left behind, replaced by the donor’s normal mitochondria.
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Zhang’s team then fertilized the new egg with the father’s sperm. Et voila, three parents! This new technique in mitochondrial replacement therapy is called spindle nuclear transfer.
Embryologist Jacques Cohen pioneered the three-person fertility procedure in the 1980s through an original technique that used cytoplasm, but the U.S. Food and Drug Administration never gave it the green light in the United States. When Zhang was contacted by the Jordanian couple, who had experienced four miscarriages and the deaths of two children over the course of 20 years, he decided to perform the procedure for them in Mexico.
A third method of performing the three-parent fertility procedure is called pronuclear transfer. In this method of mitochondrial replacement therapy, eggs from the mother and donor are fertilized before the mother’s nucleus replaces the donor’s and the donor’s nucleus is discarded. But since the donor’s egg is fertilized first, this method requires the destruction of an embryo. The Jordanian couple, who are devout Muslims and not comfortable with the destruction of an embryo, decided to try mitochondrial spindle transfer instead, according to New Science.
Some critics are calling out the decision to perform the procedure in Mexico, where there is less regulation. Others raise ethical questions about using three parents to birth a child, though the genetic material from the donor is incredibly small.
Last year, the United Kingdom became the first country to pass laws approving pronuclear transfer. In February 2016, the FDA asked the National Academies of Sciences, Engineering and Medicine to review the ethical, social and policy issues surrounding three-parent procedures as a first step toward possible approval in the U.S. The group concluded “it is ethically permissible to conduct clinical investigations of mitochondrial replacement techniques,” but a path forward isn’t so clear: A federal regulation passed in 2016 prohibits the FDA from permitting any procedure in which a modified embryo is implanted in a woman.
The research for these fertility treatments is still developing, and Zhang’s team, who published some information online, plan to present their full findings at the American Society for Reproductive Medicine’s Scientific Congress in Salt Lake City in October. They waited to announce the child’s birth in order to confirm he is in good health, as some children previously born through the three-person method still acquired harmful genetic material.