Gymnastics for the neck of Dr. Shishonin, the video of which we propose to watch, ...
- The technology, tested overseas, allows parents with genetic abnormalities to edit the mother's egg and, as a result, have a healthy child.
- Specialists from New York conducted a successful experiment in Mexican territory, because there are no laws prohibiting this. The technique is officially legalized only in the UK.
In fact, the miraculous birth took place five months ago, but only now experts have found it possible to declare the event a success. Like all people on planet Earth, a little boy has DNA with genes from both parents. However, in his hereditary code there is also a small fragment of donor DNA - that is, the genes of a third person. Therefore, with a certain stretch, we can say that the parents of the little Arab are not two, but three.
This genetic trick means that the child did not inherit from the mother a mutation that could have killed him at an early age. The boy's father and mother are citizens of Jordan. Well, the technology itself, which can cause an avalanche of disputes, is legally approved only in the UK.
However, the procedure was carried out by specialists from the United States in a territory where there are no laws at all according to which this experiment could be banned. American embryologists from medical center New Hope (New York) hope their success will green light an unusual technique in various countries world, which will give hope to millions of genetically imperfect men and women to acquire normal, healthy offspring, that is, not to give birth to children who are obviously doomed to an early death.
For the first time in history, hereditary information from three people allowed a newly born little man to avoid terrible disease. And now doctors know for sure that by reconstructing the mother's egg (and only in this way, and not otherwise), it is possible to ensure that the child is born healthy.
The boy's parents, whose names were not released, have already lost two children due to a hereditary disease called Leigh's syndrome (subacute necrotizing encephalomyopathy). This is a very rare mutation leading to severe brain damage at a very early age. The first child of the tragic couple died at the age of six months after severe torment, the second - at the age of 8 months. Usually such children do not live up to 4 years, dying from pulmonary insufficiency.
The genes that cause Leigh's syndrome were found in the mother's mitochondrial DNA, which was determined by genetic analysis. It is worth noting that mitochondrial genes (and there are only 37 of them) are never inherited through the father.
Dejected by the loss of two offspring, the couple went to America in order to ask for help from the staff of the New Hope Center, which is engaged in innovations of this kind. Since American laws do not allow genetic manipulation of human mitochondrial DNA, parents and doctors went to Mexico. Doctors removed the nucleus from the cell and transplanted it into a nucleus-deprived donor egg, the mitochondria of which did not contain the genes that cause Leigh's syndrome. This egg was then fertilized in vitro with sperm from the child's father.
This procedure was repeated five times, and as a result, one of the eggs survived and began to divide. Thus a new life was born.
Doctors write that the possibilities of the tested technique are endless - in the matter of ridding human fetuses of hereditary defects. How far specialists will go in its use is still difficult to say. Still, there are risks and quite a lot of them. But the first step, as they say, is taken on quite solid ground.
About the birth of the world's first child "from three parents", who was born after a pronuclear transfer. This term means that the baby is a carrier of the DNA of three parents - the main one from the father and mother and the mitochondrial DNA from the female donor.
Previously, we recall that this kind of technique was used only to save children from hereditary diseases.
The baby, conceived in an unusual way, was born on January 5, 2017. His mother was a 34-year-old woman who suffered from infertility for 15 years and eventually, together with her husband, decided to take an important step. The director of the clinic and geneticist Valery Zukin announced this at a recent press conference.
Prior to this, a woman in many local and foreign clinics tried to get pregnant with IVF, but each time the procedure ended in failure. The reason for this, doctors called in this particular case the impossibility of developing embryos to the blastocyst stage (this is one of the early stages of embryo development).
That is why the use of donor eggs was the only way for this couple to have a baby. Let us explain that after fertilization, two cell nuclei (pronucleuses) are formed in the egg - from the mother and from the father. Reproductologists remove both of these nuclei from the mother's egg and transfer them to a donor egg, from which two nuclei are also removed before this (it is called enucleated).
In this way, scientists get a "reconstructed" zygote (that is, a fertilized egg), which in this case had a genetic set of about 25,000 genes from mom and dad, and another 37 genes from a donor. Therefore, this method is called the birth of "three parents." It avoids the development of genetic diseases in the newborn: "unnecessary" genes remain in the original egg, and the genetic material in the nuclei is transferred to the donor cell and remains intact.
When the baby was born, the researchers conducted many tests and confirmed the presence of genes from three people. This case was the first of its kind, but most likely will not be the only one: already in March 2017, another baby is expected to be born, conceived in the same way.
Irina Sudoma, scientific director of the Nadezhda clinic, also noted that the new reproductive method is indicated to prevent mitochondrial diseases in a baby during normal conception, and also if, for some reason, the mother's eggs cannot develop normally into embryos in the early stages. “There are couples whose embryos have significant chromosomal damage, which are also caused by mitochondria. This method is also indicated for such patients,” she added.
Note that mitochondrial diseases are diagnosed in a child only after his birth. They can manifest themselves in severe mental disorders, neuropsychiatric disorders, some forms of cardiomyopathy, visual impairment. Often they lead to early death of a person.
The legislation of Ukraine does not yet regulate the norms for the use of such reproductive technologies, but the experiment was approved by the relevant ethical committees.
Recall that in September 2016 in Mexico, the first child was born who can be considered parents. True, for his conception, a technique was used that was somewhat different from the Ukrainian one.
In the meantime, the British authorities have a procedure for the birth of children with genetic material from three parents. In the United States, it was also allowed to create children from three parents, but.
In Ukraine, the second in history "child from three parents" ("three-parent baby") was born. The first such baby was born in September last year in Mexico. What kind of medical experiments and which of the mothers will the child look like?
Ethics or medicine?
Why did the first such children appear not in New York, for example, but in Mexico City and Kiev - in countries that are not at all leaders in the medical world? The answer is simple: because in Mexico and Ukraine it is not prohibited, as, for example, in the USA. That is why a team of American doctors went to Mexico to perform an operation there. In Kiev, they did it themselves in the clinic of reproductive medicine.
So far, where the "production" of such children is officially allowed - the United Kingdom of Great Britain and Northern Ireland. But they do not rush things and work according to plan. Back in 2015, they announced that they would have their first child from three parents towards the end of 2017. So it's possible that his in vitro conception (IVF) process is taking place in London right now.
normal development
To understand what a child receives from each of the parents, you need to look at how it happens in the usual, natural way. When a sperm fertilizes an egg, the nuclei of both sex cells, which contain DNA, merge. As a result future child inherits 50% of the genes (it is essentially DNA) from the father and the same amount from the mother.
But besides this hereditary information contained in the nucleus of cells, there is still some DNA in the mitochondria. These are such power stations of the cell that produce energy and freely float outside the nucleus - in the cytoplasm of the cell. This DNA encodes information that is important for mitochondria - it determines how and how much they will produce energy and how it will be used.
This is important for athletes: there are mitochondria ideal for sprinters and long distance athletes. There are mitochondria with which people are better off not exercising at all. There are mitochondrial diseases in which the child develops poorly. First of all, his brain and muscles suffer. With severe changes, such as with Leigh's syndrome, children usually do not live up to 1-2 years. So it was with the woman who was the first to bear and give birth to a child from three parents - several of her children died.
But it is important that mitochondrial DNA does not affect our appearance, character, behavior. And it is also extremely important that this DNA is transmitted to the child only from the mother - 100 percent. Why? He receives one nucleus from his father, and all other parts of the spermatozoon, including mitochondria with DNA, go to waste. And the basis for the development of the unborn child is always the egg, it is she who, after fertilization, begins to divide, forming an embryo. And on the basis of its mitochondria, the mitochondria of the unborn child are formed.
A combination of three elements
In order to rid him of defective mitochondrial DNA, a second mother is needed - a donor with normal healthy mitochondria. How it works? Imagine a combination of three elements.
1. Mother's egg
2. Egg from a female donor with healthy mitochondria
3. Father's sperm
And then you need to make sure that the egg cell of a donor woman, but devoid of a nucleus, becomes the basis for the development of the unborn child. Instead, you need to put the nuclear DNA of the mother and father. As a result, the child will receive almost all heredity from his parents, and only mitochondrial DNA from the donor.
How they did it in Mexico, explains Peter Chumakov, professor, doctor of biological sciences, acting. Head of the Cell Proliferation Laboratory of the Institute molecular biology them. V.A. Engelhardt: “So that mitochondria with DNA from the mother's egg do not get to the child, they did this. The nucleus was taken out of her, and the nucleus of the donor egg was replaced with it, after which she was fertilized with her father's sperm. That is, genetically the child inherits all the traits of his parents, which are encoded in the nucleus. Except for mitochondria, which reproduce autonomously in the cytoplasm and originate from a donor. It is important that, in principle, the technique is simple and well-established in laboratory conditions. It is still not completely clear how the small number of maternally diseased mitochondria, which are inevitably introduced during nuclear transplantation, will continue to behave. Will they crush healthy donor ones? But as long as the baby is healthy. And, of course, this is not cloning, and no fertilized eggs and embryos died during the procedure. So it's ethically acceptable."
What did they do in Ukraine
The father's spermatozoa fertilized both eggs - the mother's and the donor's. Then the nucleus was removed from the donor cell, replacing it with an already fertilized nucleus from the mother cell. And it was already introduced into the mother's uterus, as is usually the case with IVF. In this case, only one of the two fertilized eggs developed further, becoming a hybrid. In principle, this can cause criticism and prevent such manipulations in many countries.
According to Ukrainian doctors, in March in Kiev they are expecting the birth of a second child from three parents. The pregnancy is said to be going well. Another feature of the Kiev cases is that they are associated not with the early death of children born with mitochondrial defects, but with infertility and the inability of women to bear a child. They had multiple miscarriages after IVF - the embryo did not develop and died. This may also be due to damage to mitochondria, because their energy is also needed for intrauterine development.
Cutaway model of mitochondria
Gregory Han/Flickr
Ukrainian reproductive specialists told about the birth of the first child in the country with the DNA of three parents - the main one from the father and mother and the mitochondrial DNA from a donor woman, UNIAN reports.
The procedure of mitochondrial replacement therapy (MRT), which was carried out by the staff of the Nadiya clinic, is aimed at giving birth to healthy children in women who suffer from mitochondrial defects. There are two methods of MRT. One of them is that the nucleus of the mother's egg, which contains the main genetic material, is transplanted into a donor egg with a previously removed nucleus, after which it is fertilized with the father's sperm. As a result of such a procedure, carried out by employees of the New Hope clinic in New York in Guadalajara, Mexico, in the summer of 2016, the first ever child from three parents.
The second method, which was used for the first time in the world by Ukrainian doctors, is that a mother's egg with defective mitochondria is first fertilized and then transferred to a donor egg without a nucleus, the nucleus already containing the DNA of both parents (this technique is called pronuclear transfer). In both cases, the resulting embryo is placed in the mother's uterus for gestation, as in a conventional in vitro fertilization (IVF) procedure.
“With the help of pronuclear nuclear transfer, a 34-year-old woman with infertility for 15 years was able to give birth to a genetically healthy “her own” child. For many years she tried to get pregnant using the IVF method in Ukrainian and Israeli clinics. At the beginning of January, "our" child was born. For the first time in Ukraine, the reproductive specialists of the Nadezhda clinic managed to achieve pregnancy due to the pronuclear transfer of the parents’ nuclei into an enucleated (devoid of their own nucleus) donor egg,” said Valeriy Zukin, director of the Nadiya clinic, at a press conference. According to him, the presence of DNA from three people in the child was confirmed by tests carried out in laboratories in Ukraine and Germany.
Previously at the World Congress on Reproductive Technology Art 2016 in New York, Zukin reported that two of his patients underwent pronuclear transfer MRT, who do not have hereditary mitochondrial diseases, but due to mitochondrial deficiency, they had miscarriages in the early stages.
Currently, the MRT procedure is officially allowed only in the UK, although such experiments have not yet been carried out there. In most countries, this issue is currently not regulated by law. Experiments in Mexico and Ukraine were approved by the respective ethical committees.
However, MRT is systematically criticized by experts. They are concerned about the lack of data on the effectiveness and safety of this procedure for the child and his future offspring. There have also been repeated calls for MRT to be performed only on male embryos, since males do not pass on their mitochondria to their offspring. At the same time, one of Zukin's patients was reported to be pregnant with a girl (the sex of the child born was not indicated in the UNIAN note).
The baby boy, born by New Hope staff, is healthy and doing well. Also, according to information Nature e, a child of three parents was born in China, and a publication dedicated to this is now under peer review in one of the scientific journals.
The news is all about the birth of the first child through a highly controversial genetic technique, with which it may be possible to avoid the transmission of a potentially fatal hereditary disease. In addition to directly pushing the limits of in vitro fertilization, this technique has become famous because it allows a child to have three genetic parents at once. It is reported that a small boy conceived in this way was born 5 months ago, the conception itself was carried out in Mexico by a specialist from New York due to less stringent rules regarding the manipulation of human embryos in this country than in the United States, where permission was refused to conduct the experiment.
Until now, we do not know all the details. The New Scientist featured Dr. John Zhang, of the New Hope Fertility Center in New York, holding a newborn in his arms and telling the story of the child's family. The couple lost their two oldest children to mitochondrial disease, a very rare condition caused by a defect in the DNA of mitochondria, the organelles that provide energy to the body's cells. Babies inherit mitochondrial DNA from their mother, and if the mother carries a mutation in that DNA, a wide variety of life-threatening conditions can simply kill newborns.
Zhang was reported to have used a technique called targeted nuclear transfer that could create five human embryos at once. The method involves removing the nucleus - and, accordingly, most of the DNA from one mother's egg, and introducing this nucleus into the donor's egg, devoid of its own nucleus. The result is an egg with mitochondrial DNA from a healthy donor and nuclear DNA from the mother. Five donor eggs prepared in this way were fertilized with the husband's sperm, but only one of the embryos had a normal number of chromosomes. This embryo was implanted into the mother's body.
Zhang agreed to give an additional interview (“The desire of the patient is important to us,” explains a member of the marketing department of the Science Clinic)& But many scientists were concerned about the way Zhang’s team communicated the development, as well as the fact that the experiment took place in an environment of negligible supervision.
In addition to what was published in the New Scientist, another source of information is devoted to the details of the negotiations that are planned for the October meeting. American Society reproductive medicine. According to the annotation, at 3 months the child's health did not cause any concern, but nevertheless, the affected mitochondrial DNA of the mother still remains in approximately 1% -2% of the cells of the newborn's body examined for pathology. However, this child does not have any clinical manifestations of Leigh's syndrome, a disease that has already killed his brother and sister.
The limited information in the article left a large number of questions. “Right now it’s just ‘we did it, exactly what was expected of us,’” says Dieter Egli, a stem cell biologist at Columbia University. Unanswered questions remain about the presence and reaction of the ethics committee to the in vitro fertilization procedure. (The article mentions that the Council, after reviewing the problem, approved the experiment, it does not specify exactly where this happened - in Mexico, or somewhere else), what further medical supervision the child will receive, whether the research team used this technology for the first time and whether there will be more such attempts. "These and others important questions remain unanswered because this work has not been published, hence the rest of the scientific community has not been able to review it in detail,” writes Dusko Ilic, a science journalist specializing in stem cells at King’s College London. “It is imperative that this happens in the near time".
Norbert Gleicher, a fertility specialist at the Center for Human Reproduction in New York, says the New York team's decision to work in Mexico is entirely expected, given all the obstacles to trying such an experiment or even applying for approval in the United States. Gleicher says that he once sought a meeting with the Association medicines United States to discuss a mitochondrial DNA replacement technique for the country's patients, including as a treatment for infertility. “We couldn’t even get an appointment,” he admits.
The United Kingdom, as well as the American National Academy of Sciences, has given its support for the possibility of the theory of mitochondrial transmission in order to prevent disease. However, in the United States, Congress banned the Drug Association from any experimental treatments. "The regulation situation in the United States is something that doesn't make any sense," says Gleicher.
Egli agrees. "It's important to me that regulators like the Drug Association move forward, too," he said. "After all, then it could be done by the scientific groups of the United States, who have many years and even decades of research experience behind them."
Clinical embryologist Jacques Cohen of the Institute of Reproductive Genetics in Livingston, New Jersey, who advised Zhang's team on how best to resolve regulatory issues, defends his decision to perform the procedure in Mexico due to US restrictions. "Just because it was done in Mexico doesn't mean it wasn't done ethically," says Cohen, who himself ran controversial fertility experiments in the 1990s involving cytoplasmic translocation that resulted in babies also had three genetic parents.
Zhang is no stranger to embryo modification techniques. In 2003, he did something similar in China, moving the nucleus from one egg to another, although in this case the egg was also fertilized. The news was published, including in The New York Times, but the research paper describing the experiment only appeared last month in inReproductive BioMedicine online. As a result of the experiment, a 30-year-old woman became pregnant, but both of her twins died before birth.
In 2009, a group led by Shukrat Mitalipov of the University of Oregon Health and Science in Portland revived the debate about mitochondrial replacement therapy with successful results in macaques. Like others, Mitalipov expressed dismay in his statement to Science that desperate parents were simply forced to leave for countries with less control. He attributed control to Congress, which is preventing the Drug Association from authorizing the mitochondrial replacement procedure.
