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HKONG NGO – Chinese scientist claims to have used CRISPR-Cas9 genome modification technology to modify DNA in human embryos, resulting in the birth of twin girls a few weeks ago, knocked out by the organizers of the International Summit on the Modification of the Human Genome. scramble to evaluate the application two days before the scheduled date for the scientist's conference.
"I do not know the details" of He Jiankui's claim, said David Baltimore of the California Institute of Technology, chair of the summit's organizing committee, which begins Tuesday in Hong Kong. "We do not know what will be said" when he speaks during a session on the editing of human embryos.
Dr. George Daley, dean of Harvard Medical School, a member of the organizing committee, said that he had been invited to speak at the summit following a conference that he had given in 2017 at the Cold Spring Harbor laboratory for genome modification in human, monkey and mouse embryos. In this session, he described the modification of target DNA in human embryos created by in vitro fertilization, resulting in few unintended changes ("non-targeted effects"). The most serious problem was that only a part of the embryo's cells had been successfully modified, giving rise to so-called mosaicism.
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But he then explained that he was able to increase the proportion of edited cells by injecting CRISPR-Cas9 to very early embryos twice: once when they consisted only in one cell and once again when they consisted of two cells.
In his 2017 speech, he had not said that he was considering using modified IVF embryos to initiate a pregnancy. He concluded his presentation by citing the case of Jesse Gelsinger, whose death in 1999 in a gene therapy trial, a much less accurate precursor to genome editing, had delayed this field for more than a decade. He urged scientists considering embryo editing to proceed slowly and "cautiously" because "a single case of failure will kill the whole field".
His claim, first reported by the Associated Press, was not supported by a scientific paper, leaving scientists unaware of the success of genome editing. He used CRISPR-Cas9 to disable a gene called CCR5, which produces a receptor that allows HIV, which causes AIDS, to enter the cells. People lacking functional CCR5 genes are therefore immune to HIV infection.
A 2017 report from National Academies on Genome Publishing has identified CCR5 as a potential target for embryo editing by CRISPR-Cas9. "We discussed it, but it was not the focus of the report," said bioethicist R. Alta Charo of the University of Wisconsin, who co-chaired the committee of academies that produced the report. Since the modification of an embryo alters its sperm or egg producing cells, or its germline, these changes will be passed on to any future offspring.
Germ line modification is considered more ethically challenging than genome modification for treating a child or an adult, which would only alter, for example, blood-producing cells in a person with sickle cell disease and not of hereditary DNA. On the eve of the Genomic Modification Summit, Charo said: "The germline edition must therefore break a higher ethical bar.The potential risks and benefits for the child that would develop from the beginning to the next. an edited embryo must be carefully evaluated, "she said.
In the case of binoculars, the benefits are unclear. Their father is HIV positive and the sperm can carry HIV, said Daley. But there are other ways to prevent a father from transmitting HIV to his children, for example by washing sperm.
And HIV is both preventable and treatable, said MIT biologist Richard Hynes, who attends the Hong Kong meeting and co-chaired the panel of national academies: "We have set rigorous criteria that must be met" I said. "This should only concern serious unmet medical needs and informed consent needs to be in place. All these things must be examined "to see if the experience he fulfilled fulfilled the criteria. For example, on the consent forms, parents were asked to sign. He called his work "development of an AIDS vaccine," reported the AP. It is therefore difficult to know if the parents of the girls understood what he was going to do.
The risks of genome modification in general include DNA modification other than the targeted genes, which could have unintended consequences on health. Without a detailed scientific article, no one knows if CRISPR has modified girls' DNA elsewhere than in the CCR5 gene. The specific risks of having a deactivated CCR5 gene include a higher risk of infection with West Nile virus and death from influenza. He did not specify when he had clearly communicated these risks to parents.
His work would be illegal in the United States, which prohibits the editing of embryos, and in many other countries.
Surveillance groups quickly denounced his work. "If true, it amounts to an irresponsible and unethical experimentation on human beings and a serious violation of human rights," said Marcy Darnovsky, executive director of the Center for Genetics and Society, in a statement. "We wish the best for the health of these babies, but strongly condemn any waterfall that threatens their safety and endangers the rest of us. Opening the door to a society that owns and possesses genetic resources undermines our chances for a fair and equitable future. "
The concern aroused by "the rich and the haves" refers to the fear that an embryo publisher for desirable traits will one day be available to parents who can afford it, thus exacerbating Social inequalities.
"It is possible that under the circumstances [the experiment] Robin Lovell-Insigne of the Francis Crick Institute, based in London, told reporters Monday before the summit on genome editing. "But we just do not know it. We must wait to hear it, "he said, referring to the presentation of the upcoming summit.
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