We design the next generation – Is it ok to create the perfect baby?
Genetically modified children are now a reality. Researchers have for the first time, exchanged diseased genes in fetuses and probably also created babies that are resistant to HIV. But this is not the first time we are experimenting with our children's genetics.
Chinese scientist He Jiankui (right) has probably created the first gene-edited child using the gene technology CRISPR.
What is CRISPR?
The gene technology CRISPR can erase a genetic disease from a fetus. But it can also be used to change properties such as hair color or the risk of becoming overweight.
CRISPR can potentially tailor the genes in an egg cell. And the technology is also considerably simpler and cheaper than other methods of altering genes. CRISPR consists of two basic parts. The first is an rna molecule, whose sequence of rna bases corresponds to the dna bases in the gene that scientists want to change. The other is a protein called Cas9, which is bound to the rna molecule and which can cut off a DNA strand.
The two tools are injected into the cells in which the gene is to be altered. The RNA molecule now acts as a guide to look for the gene, and Cas9 is like a scissor that cuts off the gene. The cell tries to put the gene back together,
but because it often gets wrong, the gene can be destroyed and put out of play. This trick can be used, for example, if researchers want to eliminate a gene that might otherwise cause disease.
CRISPR can be used to correct genes that are critical to the child's appearance or in genes that affect the risk of illness, including mental disorders and lifestyle disorders. The method has probably already been used to create children who are resistant to HIV, but most researchers do not believe CRISPR is ready for that purpose yet.
First, the technology can give rise to unwanted mutations that harm the child. Second, it can accidentally create children in which only some of the body's cells have been gene-edited.
Researcher He Jiankui announced in 2018 that with the help of the gene tool CRISPR he had created two girls with a mutated gene CCR5 - a gene that plays an important role when the body is infected with HIV.
Virus binds to receptor on cell
Over 99 percent of the earth's population has a receptor called CCR5 on the surface of its immune cells. If the body is affected by HIV, which can potentially cause AIDS, the virus particles will bind to CCR5 and thus to the immune cells.
Cell opens for viruses
When the HIV particle is bound to CCR5, the immune cell begins to eat up the particle, which thus enters the cell. There, HIV releases its genetic material and begins to produce itself. The virus is then spread in the body and destroys the immune system.
HIV cannot infect the cell
With the help of CRISPR, it is possible to destroy the gene encoding the CCR5 receptor. The result is an immune system that is resistant to HIV. However, the lack of CCR5 may make the body more vulnerable to other diseases.
With CRISPR, doctors do not discard fertilized eggs with unwanted properties, but instead correct the egg's genes and let it live.
The mutations behind hereditary diseases can be corrected in the fertilized egg, so that it develops into a person who neither has the disease nor risks passing it on to their children.
In theory, CRISPR can also be performed on adults and thus treat genetic diseases that are discovered or occur only later in life, such as cancer or muscle loss.
CRISPR can in principle be used to design children with all conceivable characteristics such as blue eyes, mathematical talents, great empathic ability or strong muscles.If CRISPR is used to change the genes in a fertilized egg, there is no way back. New features are inherited down to future generations.
One chromosome too much. In 1968, US doctors performed a chromosome test on a pregnant woman’s amniotic fluid and under the microscope, they found three copies of chromosome 21. It was more than usual and a sign that the unborn fetus was suffering from Down syndrome. Shortly for the first time ever, doctors performed an abortion based on a genetic test.
Since then, such chromosome tests, as well as several newer methods, have become so common that the number of children born with Down syndrome in several countries is 50 percent lower than it would have been without the tests.
Doctors can also intervene earlier in fetal development. Fetuses created through artificial insemination can be re-tested before inserting the mother’s stomach, and diseased fetuses can be sorted away. The method is also used for another purpose. Some parents opt out of fetuses that are not sick but have undesirable genetic makeup.
The ability to control the next generation of genes in this way has given rise to a fierce ethical discussion – a discussion that, in recent years, has become increasingly intense with pioneering new technologies. Now doctors can not just sort among the fetuses. They can actively exchange or change their genes.
One of the techniques was put into operation in 2015. Then some of the fertilized egg’s own genes were removed and replaced with genes from a donor. In 2016, this resulted in the birth of a boy who thus has three biological parents.
In 2018, the debate reached new heights, when a Chinese scientist likely used the gene technology CRISPR to give a twin pair a mutation that makes them resistant to HIV. Soon, this technology will allow parents to design their children down to the smallest detail.
The boy has three biological parents
A Jordanian married couple had for ten years tried in vain to have children. When the woman finally became pregnant, the joy of grief was released as the fetus died during pregnancy. The same process was repeated during the next three pregnancies. But in 2005, happiness seemed to turn, and the couple eventually became parents of a little girl. Unfortunately, it soon became apparent that something was wrong. The child suffered from a rare hereditary disease, Leigh syndrome, which slows the development of the fetal nervous system. The girl has died at the age of six. The couple had another child, but the tragedy repeated, and after only eight months, the child died of the same illness as his big sister.
The origin of the hereditary disease lay in a mutated gene in the mother’s so-called mitochondria – small structures in the cells that create the energy that drives the cell. The mitochondria have 13 genes that are independent of the 46 chromosomes in the nucleus of the cell. In the Jordanian woman, a quarter of the mitochondria had a disease-causing mutation – not enough to make her sick – but in her children, virtually all mitochondria had the mutation.
In 2011, American physician John Zhang offered the Jordanian couple a controversial intervention. The method, which had never been tested on humans, can create an egg cell that has all of the mother’s chromosomes but whose mitochondria come from a healthy donor. After that, the egg cell can be fertilized with the father’s sperm. The couple accepted the offer, and nine months later, on April 6, 2016, they received a boy who had inherited 13 healthy mitochondrial genes from an unknown donor and who is most likely to be spared from Leigh’s syndrome.
New technologies can become more common
Several countries lack legislation that prohibits the exchange of mitochondria in an egg cell. This included Mexico, where John Zhang performed the intervention for the Jordanian couple. The UK is the first country to allow treatment actively, and more countries are likely to follow soon. So far, only a handful of children have been created using the technology, and it is difficult to say how widespread it will be.
Researchers estimate that about one in 5,000 children is born with a disease-causing mutation in the mitochondria – which corresponds to more than 26,000 children a year worldwide – and soon, treatment may be an obvious alternative for parents, especially those with mitochondrial disease in the genus.
Replacement of mitochondria is not the first technology to go from controversial to standard treatment. It did many techniques that have reduced the incidence of Down syndrome – a syndrome that affects about one in 700 newborns – several years ago. The techniques are not intended to change the genes of the fetus, but only to determine whether the fetus carries the syndrome. Then the parents have to decide whether or not they want to have an abortion.
The techniques include measuring a fluid gap in the neck of the fetus, measuring some proteins in the pregnant woman’s blood, as well as genetic tests on amniotic fluid, placenta biopsies or the pregnant woman’s blood.
In several countries, the methods are offered to all pregnant women, and when the tests show that the fetus has Down syndrome, about 90 percent of pregnant women choose to have an abortion. Recently there has been a slight tendency for this figure to decline.
The tendency may be because new research in Down syndrome has made the ethical debate more nuanced. Down syndrome, to some extent, causes physical and mental distress. Still, researcher Nora Shields from La Trobe University in Australia believes that the problems do not necessarily reduce the quality of life.
Shields conducted a well-known well-being study among 75 children and young people with Down syndrome and found that they enjoyed school just as well as healthy children and that they had an almost as good relationship with their parents and were nearly as independent. Generally speaking, their mental well-being was slightly lower than that of other children, and when it came to physical well-being and social contact with friends, children and young people with Down syndrome performed significantly worse than healthy children.
But the problems were most evident in teenagers. Younger children had at least as good on most points as their healthy peers. The question of whether children with Down syndrome can have a good life is far more complicated than previously thought.
Parents choose their children
Another technique goes a step further than the well-known tests for Down syndrome. It can not only detect the extra chromosome that causes Down syndrome. It can find any mutation in the fetal DNA. And the parents get the chance to opt-out of the fetus before the mother has even become pregnant.
The method is called egg sorting or PGD – preimplantation genetic diagnosis – and it makes it possible to examine the DNA of a few days old fetus that has been created by artificial insemination and has grown in a laboratory. The doctors pick out a few cells from a fertilized egg that has been divided for about five days. Then they look for known mutations or chromosome errors using various genetic engineering methods. Parents can request that several fetuses be analyzed and then, based on results, select one or more fetuses to be inserted into the woman’s womb.
There are many countries, such as the Scandinavian countries, where egg sorting is only allowed in special cases. Treatment is, among other things, permitted if the fetus is at high risk of suffering from a genetic disease. It is relevant when parents carry disease-causing mutations and therefore risk passing on the same disease.
In these cases, doctors only search for known, probable mutations – it is illegal to search for other mutations or genetic traits. Thus, parents cannot choose a fetus based on characteristics unrelated to illness, such as appearance and gender.
Many other countries have a looser or no regulation in this area, and some travel agencies have focused on arranging trips, for example, Georgia, where fertility clinics are ready to perform egg sorting. There, parents have the opportunity to choose their wishing children.
The British newspaper Daily Mail conducted a survey of egg sorting in the United Kingdom in 2018, which revealed that several fertility clinics offered parents to choose the child’s sex despite being banned in British law. However, several hundred couples had paid over SEK 100,000 for the treatment, which was then performed abroad.
In the US, there have been examples of disabled parents who have wanted to have children with the same disability, so that children and parents reflect each other. In 2002, a lesbian couple, two deaf women, fertilized one’s eggs with sperm from a deaf donor and then asked doctors to select a fetus that would most likely be deaf.
The doctors did what they were paid for, and the couple got a deaf wishing child. In another case from 2006, a short-grown couple wanted to be sure of having a child who, like them, was also short-grown.
In many countries, this is not allowed, but women can, on the other hand, seek permission to use the method to have a child with a specific composition of proteins in the cells. With the right composition, for example, the child can donate stem cells to another child.
It may be desirable if the woman already has a child with a severe illness, such as leukemia, who can be cured by stem cell transplantation. Then the doctors select a fetus, which after birth can become a stem cell donor to a big brother or big sister.
Researchers are changing twins’ genes
So far, parents have only had the opportunity to select a fetus from among a few possible or exchange the genes found in the fetal’s mitochondria. But new technology makes it possible to take a fertilized egg and give it exactly the genetic traits that parents want. The technique is called CRISPR, and with it, doctors can, with high precision, destroy certain genes and correct any errors. For the past seven years, CRISPR has become an indispensable tool for researchers who are to investigate cells or animals with certain properties in the laboratory.
Since the technology invented, there has been a heated debate about the use of CRISPR on human fetuses. Therefore, it attracted considerable attention when biophysicist He Jiankui of the Southern University of Science and Technology in Shenzhen, China, announced in November 2018 that the world’s first CRISPR modified babies come to the world.
The two little girls, Lulu and Nana, are twins and well-formed – and they are most likely resistant to HIV thanks to a mutation that He Jiankui and his colleagues have introduced into their DNA.
Jiankui’s statements are not yet verified with certainty. Still, not many researchers doubt that he is telling the truth – and a provisional investigation by the Chinese government appears to confirm the truthfulness of the statement.
One concern among researchers is that CRISPR may inadvertently create DNA mutations other than those desired. He Jiankui admits that he found an unwanted mutation in one of the fetuses, but believes the mutation is harmless. Other researchers doubt that the claim is valid, as previous attempts indicate that unintended mutations are relatively common.
Even if the CRISPR technology were flawless, genetic modification of human fetuses would have raised a large number of issues. When is it ethically justifiable to change a child’s genes? For example, is it justifiable if the child would otherwise suffer from severe illness such as cystic fibrosis? Or if the child was at increased risk of developing depression later in life? He Jiankui performed his procedure because the twins’ father was HIV infected.
But it is highly unlikely that the girls would have been infected by the father, which is why many researchers believe that He Jiankui’s act cannot be defended ethically.
Even more alarming is that He Jiankui may have paved the way for an illegal market, where parents can have tailor-made children based on desires such as hair colour, eye colour and height. CRISPR is a surprisingly simple technology, and even today, it is quite possible for ordinary people to order the necessary equipment on the internet at a relatively low price.