In 2018, He Jiankui shocked the world by announcing that he had created babies with altered genomes, implanting embryos in which he had used CRISPR-Cas9 to edit a gene known as CCR5, which encodes a co-receptor for the HIV virus, in order to make them resistant to infection.

The implantation resulted in the birth of twins in 2018, and a third child was later born to separated parents. The fathers had accessed treatment because they were HIV-positive and the mothers HIV-negative, and the couples did not have access to alternative assisted reproductive technologies in China.

In December 2019, He Jiankui, who was responsible for the experiment, was sentenced to three years in prison. Faced with his likely release, some bioethicists are calling on the Chinese government to establish a research center dedicated to ensuring the well-being of these first genome-edited children born. On the other hand, others worry that close monitoring will lead to unnecessary surveillance of children that could backfire on them.

He Jiankui’s experiment was widely condemned by scientists around the world, who called for a global moratorium on the editing of embryos intended for implantation. Since then, various ethics committees have come to the conclusion that the technology should not be used to carry out genetic modifications in human embryos, which are likely to be transmitted to heredity, given the lack of safety of these tests and their unpredictable future consequences.

As stated in an article signed by Zaria Gorvett, the most serious of all were the mistakes he made, since the babies involved, Lulu and Nana, are not necessarily immune to HIV, but have been accidentally provided with versions of the CCR5 gene, which is the result of a new genetic design and completely different from the normal gene. Nana carries two altered genes, while Lulu, her twin, has one altered and one normal.

Errors in gene editing

In experiments with genetically modified animals, this field has been found to be riddled with errors and unwanted effects, such as rabbits altered to be slimmer that inexplicably ended up with much longer tongues, or cattle modified to lack horns that was given bacterial DNA, including some genes that confer resistance to antibiotics.

Researchers at the Francis Crick Institute in London recently found, by analyzing data from earlier experiments, that approximately 16% had accidental mutations that would not have been detected by standard tests.

While it is believed that Nana’s two CCR5 genes could protect her from HIV, one of Lulu’s two genes remained its natural version, meaning she could be susceptible to the virus.

The experiment ended up inventing new mutations and did not alter all the cells. This “mosaic” effect arises from the fact that it is easier to edit embryos than it is to alter a newly fertilized egg, which consists of a single cell.

But when editing an embryo, not everything is necessarily uniformly affected by the edits: some cells will keep their original genetic makeup, while others will be altered.

As different organs and tissues develop, this variation remains, so if you had four starting cells, one of which was given a mutated CCR5 gene, you could end up in 25% of the cells in the body.

In addition, it is now known that the CCR5 gene has, in addition to the function already described, others that include brain development, recovery from strokes, Alzheimer’s disease, the spread of certain cancers, and the result of infection with other pathogens.

Indeed, typical CCR5 proteins are thought to protect against a variety of pathogens, including malaria, West Nile virus, tick-borne encephalitis virus, yellow fever, and respiratory viruses such as influenza, suggesting that editing may have robbed his subjects of a useful genetic adaptation against infectious agents and other pathologies.

Opinion of expert researchers

Qiu Renzong, of the Chinese Academy of Social Sciences in Beijing, and Lei Ruipeng, of the Huazhong University of Science and Technology in Wuhan, have published a document stating that children need special protection because they constitute a “vulnerable group”. Gene editing could have created errors in children’s genomes, which could be passed on to their children.

They recommend the periodic sequencing of children’s genomes to detect anomalies, including genetic testing of their future offspring, as well as passing on the medical expenses generated by this follow-up to the principal investigator, He Jiankui, at the University of Science and Technology of the South in Shenzhen, with which he was affiliated, and the Chinese government.

Other scientists, such as Kirksey, a medical anthropologist at the Alfred Deakin Institute in Melbourne, Australia, agree that he should take some responsibility for children. He promised that they would receive health insurance for the first 18 years of their lives, but because the twins were born prematurely, they were initially denied coverage.

Other researchers, in this case Russians such as Denis Rebrikov, a molecular biologist and geneticist at the Kulakov National Medical Research Center for Obstetrics, Gynecology and Perinatology in Moscow, have expressed their willingness to repeat the gene editing experiment on human embryos, developing a technique to use CRISPR to edit mutations in a gene related to deafness, called GJB2.

When the opportunity to do so arises, Rebrikov plans to edit the embryos and store them before seeking permission from Russian regulators to implant them.

Kirksey mentions the case of Louise Brown, who in 1978 became the first person to be born through in vitro fertilization, a procedure that was very controversial at the time, stating that “she was subjected to all kinds of medical tests through the course of her life” who says Brown has described her struggles with leading a normal life.


Julio Tudela

Bioethics Observatory- Institute of Life Sciences

Catholic University of Valencia


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