Babies are born in the UK with the genetic heritage of three different people

Several babies with “three parents” were born in the United Kingdom following a technique of in vitro fertilization (IVF) still experimental but authorized across the Channel since 2015, according to an article by The Guardian. For reasons of anonymity, little information is available about these children and details of the medical procedures. I’Human Fertilization and Embryology Authority said he had given the green light to 32 parents to follow the same procedure, called donation of mitochondriamitochondria or three-parent IVF. The scientists of Newcastle Fertility Center are pioneers of this risky technique that is still banned in many countries. ” Less than five children would have been born from a donation of mitochondria, according to The Guardian.

The donation of mitochondria, a particular IVF

The donation of mitochondria is nicknamed three-parent IVF because the embryo doordoor genes from three different people: his biological father and mother, and an anonymous donor. Most of his heritage geneticgenetic comes from its biological parents, with the exception of the thirty genes carried by the mitochondria, which come from the anonymous donor. The procedure can be simplified as follows: a classic IVF is first performed with the egg and the spermsperm future parents. Once the embryo is fertilized, its nucleus is removed and injected into the enucleated egg of the donor. Finally, the embryo is implanted in the uterus of the future mother and if all goes well, the pregnancy begins.

This procedure was designed to limit the transmission of mitochondrial diseases from mother to child. During reproduction, it is the mother who transmits the mitochondria to the embryo, these organists present in all cells and which ensure the production ofenergyenergy. If she is a carrier of a mitochondrial disease, there is a good chance that she will pass it on to her children. According to the Institut Pasteur, 200 children are born with a mitochondrial disease each year. The latter are very varied and cause incurable and sometimes fatal heart, respiratory, muscular or cerebral problems.

Poorly controlled risks

The donation of mitochondria theoretically limits the risk of mitochondrial disease, but it does not completely eliminate it. Indeed, one of the risks of this technique is what doctors call a ” reversionreversion. » Abnormal mitochondria from the biological mother can be transferred when the nucleus of the embryo is injected into the donor egg (whose mitochondria are healthy). During development, abnormal mitochondria can multiply and ultimatelymake the child sick despite everything.

” The reasons for these reversions are not yet known, but developing methods to avoid them will be a scientifically important and reassuring step for parents, children and those performing these procedures, even though the risks of reversions occurring, while like other complications, are rather weak explains Robin Lovell-Badge, Professor at the Francis Crick Institute in London.

This is not the first time that a baby with “three parents” has been born. The first was born in 2016 in the United States in New Hope Fertility Center. The child’s mother carried the genes of Leigh syndromeLeigh syndromea disease for which thelife expectancylife expectancy does not exceed a few years. The disease was fatal for two of the patient’s children, who died at six years and eight months.

The donation of mitochondria could also be used in women who have no mitochondrial disease, but who have a series of IVF failures, or who are over 40 years old. A pilot study was launched in 2018 and a 28-year-old participant had six children following the procedure according to results published in February 2023.

To date, this applicationapplication is not permitted in the UK for women who do not have a disease. The donation of mitochondria raises important ethical questions and the risk-benefit balance of the procedure must be assessed on a case-by-case basis.