New children from three parents

Dad, Mom and Mom

Oleg Lischuk, N+1

Employees of the New Hope clinic in New York, thanks to whom the first child from three parents was recently born, said that the boy, who is now three months old, is healthy and developing normally.

Their report was presented at the annual meeting of the American Society of Reproductive Medicine in Salt Lake City ASRM 2016 and published in the collection of abstracts of the event (pdf, p. 375). Experts in reproduction and bioethics were not slow to criticize their work, and in the meantime, several more reports of similar experiments appeared, writes Nature (Reports of ‘three-parent babies' multiply).

The so-called children from three parents appear as a result of the mitochondrial replacement therapy (MTT) procedure. It is designed to give birth to healthy children in mothers suffering from hereditary mitochondrial defects. During such therapy, the nucleus is extracted from a donor egg with healthy mitochondria, after which the nucleus of the egg of the expectant mother is placed in it and fertilized with paternal sperm. Another option is to transplant an already fertilized nucleus (pronucleus) into a donor egg. The resulting embryo is transferred to the mother's uterus for gestation. A child born in this way receives the main genome from official parents and mitochondrial DNA from a female donor, who becomes the "third parent".

The first such procedure in a person was carried out by New Hope employees in Guadalajara, Mexico – such interventions are prohibited in the United States. As John Zhang, who led the work, told at the meeting, 24.5 percent of the mother's mitochondrial DNA contained a mutation that causes Ley syndrome – a severe lesion of the central nervous system. Before applying to New Hope, she had four miscarriages; two of her children died at the age of eight months and six years – their share of mutant DNA exceeded 95 percent. In a boy born with the use of MHT, this figure was only 1.6 percent. 

John Zhang with his first child from three parents

For the first time, the work of Zhang's team was reported by New Scientist at the end of September 2016. Two weeks after that, at the World Congress on Reproductive Technologies ART 2016 in New York, the director of the Ukrainian clinic of Reproductology "Nadiya" Valery Zukin said that two of his patients had undergone the MST procedure and were in the late stages of pregnancy. They did not suffer from hereditary mitochondrial diseases, however, due to mitochondrial insufficiency, their previous pregnancies were interrupted early. Current pregnancies, according to Zukin, proceed without complications.

In addition, according to Nature, there is currently an article on the review in one of the scientific journals, the name of which is not given, reporting the birth of a child from three parents in China.

The MHT procedures carried out caused a flood of criticism from the medical community. The reason for it was the lack of data on the effectiveness and safety of this procedure for the child and his future offspring. Because of this, debates around the ethics of such an intervention are conducted in most developed countries, most often the opinion is that it can only be carried out within the framework of clinical trials under independent supervision. With great restrictions, the United Kingdom allowed the conduct of the MST, but no practical experiments have been conducted in the country yet.

Also, many specialized expert councils suggest limiting the MST to male embryos only, since fathers cannot transfer donor mitochondria to offspring, and the procedure will be limited to one generation. New Hope transferred a male embryo for gestation, since he alone had a normal set of chromosomes out of all those obtained during the MST procedure. One of Zukin's patients is pregnant with a girl, the sex of the Chinese child is unknown.

George Daley, a researcher at Boston Children's Hospital who studies the scientific and ethical aspects of MST, called the New Hope experiment in Mexico an escape from tough American laws and expressed fears that such "non-standard" tests could prevent law-abiding teams from obtaining permission to conduct MST.

New Hope Clinical Director Alejandro Chavez-Badiola called these statements "scientific chauvinism." "Why is this normal in the UK, but in Mexico it raises moral questions? We have the necessary technologies and training," he said. According to Chavez-Badiola, there are no laws in Mexico prohibiting MHT, and the experiment of his clinic was approved by the ethics committee. Zukin also said that his work was approved by the Ethical Council of the Ukrainian Association of Reproductive Medicine.

Given the length of the ethical debate and the inability to assess the consequences of MHT in humans in advance (it did not cause significant complications in animal experiments), the approach of New Hope and their colleagues may be the only one capable of forcing experts and legislators to stop the discussion and develop regulations for the procedure. Thus, Dietrich Egli, an employee of the New York Stem Cell Foundation, recognizing the lack of data on the effectiveness and safety of MZT, approved the actions of the experimenters. "They showed great courage, deliberately exposing themselves to harsh criticism. I think there is a certain bias in supervision and control, because of which new types of treatment are postponed, so we need to do exactly that," he said.

Portal "Eternal youth" http://vechnayamolodost.ru  24.10.2016