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Mad Scientist
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Chinese researcher claims to have created gene-edited twins
Old news from November 2018, but...
CRISPR bombshell: Chinese researcher claims to have created gene-edited twins
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HONG KONG, CHINA—On the eve of an international summit here on genome editing, a Chinese researcher has shocked many by claiming to have altered the genomes of twin baby girls born this month in a way that will pass the modification on to future generations. The alteration is intended to make the children’s cells resistant to infection by HIV, says the scientist, He Jiankui of the Southern University of Science and Technology in Shenzhen, China.
The claim—yet to be reported in a scientific paper—initiated a firestorm of criticism today, with some scientists and bioethicists calling the work “premature,” “ethically problematic,” and even “monstrous.” The Chinese Society for Cell Biology issued a statement calling the research “a serious violation of the Chinese government’s laws and regulations and the consensus of the Chinese scientific community.” And He’s university issued a statement saying it has launched an investigation into the research, which it says may “seriously violate academic ethics and academic norms.”
Other scientists, meanwhile, asked to see details of the experiment and its justification before passing judgment.
He told The Associated Press (AP) that he altered embryos for seven couples during fertility treatments, with one pregnancy resulting thus far. In each case, the father was infected with HIV; the mothers were HIV-negative. He’s goal was to introduce a rare, natural genetic variation that makes it more difficult for HIV to infect its favorite target, white blood cells. Specifically, He deleted a region of a receptor on the surface of white blood cells known as CCR5 using the revolutionary genome-editing technique called CRISPR-Cas9.
According to the AP report, He was not trying to prevent transmission of HIV from the father’s sperm to the embryo, a highly unlikely event. The risk of transmission drops even lower when the sperm is washed before insemination through in vitro fertilization, as occurred here. Rather, He said he wanted to protect the babies from infection later in life.
The International Summit on Human Genome Editing begins here on Tuesday and many researchers, ethicists, and policymakers attending the meeting first learned of He’s claim through media reports. Organizers of the conference told reporters at a pre-event briefing they were awaiting further details.
Scientists are investigating the use of CRISPR-Cas9 as a treatment for many genetic diseases, such as muscular dystrophy and sickle cell anemia. One long-running study in HIV-infected adults has crippled CCR5 with another genome-editing technology, and a similar study is underway in China with CRISPR. But these cases involved gene editing of so-called somatic cells that are not passed on to the patient’s children. He reportedly went a step further, altering the genome in early stage embryos, which would affect sperm and eggs—the germ line—and make the change heritable. Such work is effectively barred in the United States and many other countries. Whether it fits within China’s regulatory environment is not clear.
He is scheduled to speak at the summit on gene editing on Wednesday, but organizers were unsure whether he planned to discuss his experiment. He put a series of videos on YouTube to justify the experiment and explain how it was done. He also invited viewers to send comments to his lab and to the two babies, named Lula and Nana.
Yet many scientists say the experiment was premature and the potential benefits not worth the risk. “The underlying purpose of doing the experiment was obviously to show that they could do gene editing on an embryo, but the purpose for the party involved does not make any sense,” says Anthony Fauci, an HIV/AIDS researcher who heads the U.S. National Institute of Allergy and Infectious Diseases in Bethesda, Maryland. “There are so many ways to adequately, efficiently, and definitively protect yourself against HIV that the thought of editing the genes of an embryo to get to an effect that you could easily do in so many other ways in my mind is unethical.”
Pablo Tebas, a clinical researcher at the University of Pennsylvania who led a small study that crippled CCR5 in HIV-infected adults using what’s known as zinc finger technology, similarly denounced the embryo alteration. “The experiment is not medically justified,” said Tebas, who noted that CCR5 mutants are not benign as people are more susceptible to serious consequences from West Nile infections. “Hopefully these kids will not have any health problems," he says.
“Gene editing itself is experimental and is still associated with off-target mutations, capable of causing genetic problems early and later in life, including the development of cancer,” Julian Savulescu, an ethicist at the University of Oxford in the United Kingdom, said in a statement released today by the U.K. Science Media Centre. “This experiment exposes healthy normal children to risks of gene editing for no real necessary benefit,” he says. Sarah Chan, a bioethicist at the University of Edinburgh, worries that the premature use of gene editing prior to consideration of social aspects of the work “threatens to jeopardize the relationship between science and society … and might potentially set the global development of valuable therapies back by years.”
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https://www.sciencemag.org/news/2018...e-edited-twins
...But having this CCR5-gene altered may lead to other health problems:
World's first gene-edited babies may be at early death risk: Study
Quote:
Los Angeles: The world's first babies whose genes were reportedly altered to help them fend off HIV infection are more likely to die younger, a study claims.
According to an analysis by scientists from University of California (UC)Berkeley in the US, the controversial genetic mutation that a Chinese scientist attempted to create in twin babies born last year is associated with a 21 per cent increase in mortality in later life.
The researchers scanned more than 400,000 genomes and associated health records contained in a British database, UK Biobank, and found that people who had two mutated copies of the gene had a significantly higher death rate between ages 41 and 78 than those with one or no copies. Previous studies have associated two mutated copies of the gene, CCR5, with a fourfold increase in the death rate after influenza infection, and the higher overall mortality rate may reflect this greater susceptibility to death from the flu. However, the researchers said there could be any number of explanations, since the protein that CCR5 codes for, and which no longer works in those having the mutation in both copies of the gene, is involved in many body functions.
"Beyond the many ethical issues involved with the CRISPR babies, the fact is that, right now, with current knowledge, it is still very dangerous to try to introduce mutations without knowing the full effect of what those mutations do," said Rasmus Nielsen, a professor at UC Berkeley.
"In this case, it is probably not a mutation that most people would want to have. You are actually, on average, worse off having it," said Nielsen. "Because one gene could affect multiple traits, and because, depending on the environment, the effects of a mutation could be quite different, I think there can be many uncertainties and unknown effects in any germline editing," said postdoctoral fellow Xinzhu Wei, first author of the research published in the journal Nature Medicine.
The gene CCR5 codes for a protein that, among other things, sits on the surface of immune cells and helps some strains of HIV, including the most common ones, to enter and infect them.
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https://health.economictimes.indiati...study/69719274
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07-05-2019, 06:01 PM
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