The method of mitochondrial replacement is a serious breakthrough in science

What prospects will the birth of a child from three parents open up

Alexander Emelianenkov, Rossiyskaya Gazeta

Test tube babies, surrogate mothers, and now a child constructed using the "lego" method? A sharp mind and a musical ear – from legitimate parents, and endurance, healthy kidneys, heart and omnivorous liver – from an unknown aunt from the donor mitochondria bank?

This is not a figment of an inflamed fantasy. This is our future, and it is already close, as indicated by the debates held in the UK Parliament and the decisions taken as a result of them. The House of Lords on Tuesday overwhelmingly (232 votes out of 280) blessed artificial insemination, which uses the genes of three people – one man and two women. Shortly before that, on February 3, the same issue was discussed in the lower house of the British Parliament and was also approved, and by a large margin: 382 votes in favor, 128 against. As a result, the UK became the first country in the world to legalize such a procedure for artificial conception of a person.

But – we will moderate emotions, we will hold labels and horror stories, we will try to calmly understand what is actually offered, to whom and for what it is necessary. Or – don't.

The stated purpose for which the new procedure was developed by scientists and proposed for practical use is extremely noble – to help produce healthy offspring (or at least one child) to those married couples where a woman suffers from a genetic disease.

The essence of the method, which was called mitochondrial substitution, is that during artificial insemination, along with the genes of the father and mother, the genes of a third-party woman are also used, which replace some maternal genes that have irreparable defects. Thus, scientists believe, it is possible to avoid many diseases transmitted from mother to child.

It is important to note here that the mitochondria that gave the name to the method contain only 37 genes. And all the main information that determines a person's appearance is embedded in the cell nucleus, where there are about 23 thousand genes. Do you feel the difference – 23 thousand and only 37? However, a serious mutation of mitochondrial genes transmitted through the maternal line can cause severe diseases that can cause disability and premature death. Among such threats are muscle atrophy (mitochondrial myopathy), liver, kidney, brain, heart damage, blindness.

To avoid this, scientists from the University of Newcastle, England, have just proposed the procedure of mitochondrial replacement. That is, the maternal mitochondrial DNA with an irreparable defect literally changes to the mitochondrial DNA of another woman, where there is no such defect. Back in 2010, a human embryo was created at the University of Newscala based on the genetic material of three parents.

In the description of specialists associated with IVF, it looked like this: "The researchers removed two nuclei from a fertilized egg, when they connect, an embryo is formed. Then both nuclei (pronuclei) were transferred to another egg cell, from which the nucleus was previously removed. At the same time, mitochondria and the genes contained in them were not transferred. Thus, only 0.1 percent of the donor woman's genes are transmitted to the child."

In other words, the nucleus is removed from the donor egg, and the nucleus from the already fertilized egg of the genetic mother is placed instead. As a result, the main nuclear DNA of the mother and father is preserved, due to which the child inherits their traits, and mitochondrial DNA is inherited from the donor.

"Another variant of this procedure is when the fertilization of an egg occurs after the manipulation described above has been performed with it," explains Sergey Lebedev, a member of the Ethics and Law Committee of the Russian Association of Human Reproduction. "Thus, the danger of inheritance of genetic diseases carried by the mitochondrial DNA of the genetic mother is cut off."

Proponents of such reproductive innovations believe that they will reduce the number of congenital genetic diseases. Opponents, on the contrary, talk about the inadmissibility of such interference in natural processes, since the very possibility of choosing DNA can lead to various abuses, including the conception of children with specified, at the whim of parents, qualities. The expression "designer kids" has already appeared in the British press.

Sergey Lebedev, already mentioned, states from the positions of his ethics and law committee: "Everything that has been used in reproductive medicine so far is the use of what mother nature gives us: a male sperm, a female egg, an embryo resulting from their fusion. No interference with genetics, as they say, what has grown has grown."

The proposed now is already so close to changing the genome that this line becomes very vague, and it is not difficult to cross it, the expert warns. Then, according to him, eugenics begins – ubermens, genetic castes, children with innate specialization, etc. This prospect is very frightening.

"And the most unpleasant thing is," Lebedev concludes, "that once you open this Pandora's box, it will be impossible to drive the genie back into the bottle."

How justified are such fears? How are they evaluated and what do Russian scientists and specialists practicing in this field think about the method itself?

BLITZ INTERVIEWLeyla Adamyan, Deputy Director of the Scientific Center of Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov, Chief Obstetrician-Gynecologist of Russia, Academician of the Russian Academy of Sciences.

– How do you like the latest news from London? Did they support the right thing there?

Leyla Adamyan: The method of mitochondrial substitution developed in England, I assess as a breakthrough in science, and a very serious one. Because there are rare hereditary diseases in which this is the only opportunity to produce healthy offspring. For example, muscular dystrophy, various neurodegenerative diseases – their frequency is approximately one per 5 thousand newborns. Such diseases are caused by a defect in mitochondrial DNA. It is transmitted exclusively through the maternal line. And the carrier of a defective gene, this mitochondrial problem can never give normal offspring.

– Is that why a woman is needed as a donor of healthy mitochondrial DNA?

Leyla Adamyan: Yes. It is necessary that the genetic material from a fertilized egg with damaged mitochondria be removed and transferred to a healthy donor egg with normal mitochondrial DNA. As a result of this procedure, a healthy child is born who has nuclear DNA from both parents and donor mitochondrial DNA.

– If legislators allowed such a thing in Russia, is our scientific base, practical healthcare ready to provide such services?

Leyla Adamyan: I have no doubt about the scientific base. But we have not yet reached the practical implementation of such developments in full. Therefore, it is quite natural that England, as the legislator of new reproductive technologies, became the first in this matter. Here we should be careful. This, I repeat, is a big breakthrough in science, but it still has the character of an experiment. And the experiment is justified when there is a rare hereditary disease. And it should be clearly understood that we are talking only about those patients in whose body there is an irreparable defect of mitochondrial DNA.

Sergey Kolesnikov, embryologist, Advisor to the Presidium of the Russian Academy of Sciences, Academician of the Russian Academy of Sciences.

– Did the British hurry up to transfer laboratory experiments to people?

Sergey Kolesnikov: This technology has been worked out on animals for a long time, and now, judging by the decision of the British Parliament, it can be used on humans. In a broad sense, it promotes in-vitro fertilization to a new level – to the stage of designing embryos without pathological and fatal diseases. Mitochondria, as already mentioned, carry a relatively small number of DNA genes. But at the same time they contain some special ones in which important hereditary information is encoded and transmitted through the female line.

– In what cases can a new method be in demand?

Sergey Kolesnikov: From a practical point of view, technology is needed to overcome rare, so-called orphan diseases. It can be only one person per 20 thousand patients. But potentially, if we talk about mitochondrial non-fatal diseases, there are a lot of them. Basically, such diseases are associated with hereditary disorders of metabolism and energy supply of the cell, since mitochondria are a kind of power plants of the cell. In these cases, the described manipulations with eggs can help.

– Are there any threats to ethics here? Or, for example, the danger of crossing the line beyond which experiments on "modeling" a person will begin?

Sergey Kolesnikov: As a kind of general, long-term risk, such a problem, of course, exists. But no more than that. After all, what we are talking about now is the replacement of one cytoplasm in which the embryo develops with another. There is no genetic engineering, no genetic engineering is not visible.

– Is it impossible to create an ideal soldier or, conversely, a refined personality, for example, a brilliant musician in this way, even in the long term?

Sergey Kolesnikov: This is a question, rather not to me, but to the fanstast writers. Eugenics has been and remains a popular topic, but there is little to do with it. Some part of the properties inherent in a particular person is formed in utero, and often even contrary to the genotype. But most of the human qualities are inherited socially, not genetically.

Then, don't forget: mitochondrial DNA is less than one percent of the human genome, and 99 percent is the cell nucleus. Although some kind of genome modernization with the replacement of mitochondria still happens, of course. This is mainly due to human energy, physiological and metabolic processes.

But this, I repeat, has nothing to do with genetic engineering. And in numerous IVF centers that work in Russia, embryos with defective chromosome sets are still "screened out", but it is forbidden to select embryos by gender (for example, boys) in some countries, for example, in China, during artificial insemination.

– It turns out that you do not see serious risks in the reproductive innovation of the British?

Sergey Kolesnikov: When the first test tube baby appeared in England in 1978, there was also a lot of speculation, and now millions of such children are walking around the planet. But there will be, I think, legal snags. If the child is from three parents, it is necessary to clearly prescribe the rights of each. Is the woman who gave her egg without defective mitochondria one of the parents or only a donor? And can a child born in this way be her heir? With the appropriate rights and – let's not forget! – duties to those to whom I owe the birth.

Portal "Eternal youth" http://vechnayamolodost.ru26.02.2015