First baby born in UK with DNA from three people

The first baby fertilized with DNA from three different people has been born in the United Kingdom, after doctors used an innovative In Vitro Fertilization procedure with the aim of preventing children from inheriting incurable diseases, the British newspaper The Guardian published on Wednesday. .

The technique, known as mitochondrial donation treatment (MDT), uses tissue from the eggs of healthy donor women to create embryos through In Vitro Fertilization (IVF) free of harmful mutations carried by their mothers and that they are likely to be passed on to their offspring.

Embryos combine sperm and eggs from the biological parents with tiny structures similar in shape to batteries or batteries, called mitochondria, which are those that come from the donor egg. Thus, the resulting baby has DNA from the mother and father as usual, plus a small amount of genetic material (about 37 genes) from the donor.

The process has given rise to the expression “three-parent babies”. However, more than 99.8% of the newborn's DNA comes from the mother and father, according to published information.

Research into MDT, also known as mitochondrial replacement therapy (MRT), was pioneered in the UK and started by doctors at the Newcastle Fertility Center. The goal was to help women with mutated mitochondria to have children without the risk of passing on genetic disorders.. Without this process, people inherit all their mitochondria from the mother, so deleterious mutations in the “batteries” can affect all the children a woman has.

The Newcastle process consists of several steps. First, the father's sperm is used to fertilize the eggs of the affected mother and a healthy donor.. The nuclear genetic material is then extracted from the donor egg and replaced with that of the couple's fertilized egg. The resulting egg has a full set of chromosomes from both parents, but carries the donor's healthy mitochondria instead of the mother's defective ones.. It is then implanted in the uterus.

For women affected with harmful mutations in mitochondria, natural conception “is often a gamble,” defines The Guardian. Some babies can be born healthy because they only inherit a small proportion of the mutated mitochondria.. But others can inherit many more and thus develop serious, progressive, and often fatal diseases.

One affected baby in 6,000

Approximately one in 6,000 babies is affected by mitochondrial disorders. The Guardian notes that the UK Human Fertilization and Embryology Authority, the industry regulator, facilitates approval of the procedure on a case-by-case basis and has already given at least 30 cases the green light.

Developments with the MDT led Parliament to change the law in 2015 to allow the procedure. Two years later, the Newcastle clinic became the first and only national center licensed to perform it.. The first cases were approved in 2018.

According to the English media, doctors at the Newcastle clinic have not made public the details of the births of their MDT program for fear that specific information could compromise the confidentiality of patients.. However, in response to a freedom of information request made by the newspaper, the HFEA confirmed that a small number of babies have already been born in the UK following MDT.

The regulator said the number of births was “less than five” rather than giving the exact number, because doing so “could lead to the identification of a person to whom the HFEA owes a duty of confidentiality.”. No further details about the births were provided.

A procedure not without risk

UK is not the first country to create babies from MDT. In 2016, an American doctor announced the world's first MDT birth after treating a Jordanian woman who carried mitochondrial mutations that cause a fatal disease called Leigh syndrome.. Before the treatment, carried out in Mexico, the woman had four spontaneous abortions and two children.. One died at the age of six and the other lived only eight months.

Of course, “the United Kingdom was the first country in the world to allow mitochondrial donation treatment in a regulated environment,” says Peter Thompson, Executive Director of the HFEA, in a statement. “Mitochondrial donation treatment offers families with severe inherited mitochondrial diseases the possibility of having a healthy child. The HFEA oversees a robust framework that ensures that mitochondrial donation is done safely and ethically.”. Although he points out that “It is still early for the MDT and the HFEA continues to review clinical and scientific advances.”

The procedure is not without risk.. The Guardian reports that recent research has found that, in some cases, the small number of abnormal mitochondria that are inevitably transferred from the mother's egg to the donor's egg can multiply when the baby is in the womb.. This so-called “reversal” could cause a disease in the child. “It is not fully understood why reversion is observed in the cells of some children born after MDT procedures, but not in others,” says Dagan Wells, a professor of reproductive genetics at the University of Oxford who participated in the research. .

“So far, the clinical experience with MDT has been encouraging, but the number of reported cases is too small to draw any definitive conclusions about its safety or efficacy,” Wells says.. “Long-term follow-up of children born is essential. The stage of development at which the reversal occurs is unclear, but it probably occurs at a very early stage.. This means that prenatal testing, done around 12 weeks into the pregnancy, might be able to identify if reversal has occurred.”