What about the children to whom Chinese scientists have “enhanced” hereditary information? Experts cannot agree – VTM.cz

It was a shock. In November 2018, a carefully secret report leaked to global media that twins had been born in China, to which biophysicist Jiankui He and his team had deliberately adjusted the hereditary information. He used a technology called CRISPR-Cas9, which allows targeted intervention on hereditary information.

For this experiment, he obtained couples where the partner was HIV positive and the partner was not infected with HIV. These people can produce a child without risk of infection by fertilizing in a test tube, where the HIV virus is removed from their father’s semen.

But in China, this procedure is prohibited. He promised his parents that he would arrange for them to give birth in a test tube, and that he would also experiment with an “HIV vaccine”. In fact, when it was fertilized in a test tube, it manipulated the hereditary information of the resulting embryos.

He and his colleagues have used the technique known as intracytoplasmic sperm injection to conceive children, in which the father’s sperm is injected directly into the egg under a microscope using special tools and devices. Along with sperm, He et al. CRISPR-Cas9 molecules targeting the CCR5 gene in the egg. The goal was to damage this gene.

He was inspired by the well-known fact that some people in northern Europe have the CCR5 gene damaged by a mutation in which thirty-two letters of the genetic code fell out of the gene at a very specific location. The HIV1 virus binds to the protein encoded by the CCR5 gene on the surface of white blood cells, and if a person has inherited a CCR5 gene mutation called “delta 32” from both parents, they are resistant to the HIV1 virus. The virus does not attach to his blood cells.

However, in the Chinese team’s experiment, CRISPR-Cas9 was not designed to induce a “delta 32” mutation in the embryo’s hereditary information. CRISPR-Cas9 only made “holes” of different sizes in the gene, and in the case of an embryo, it didn’t even damage the gene in all the cells of the developing embryo.

The girls born from these embryos, referred to in the media by the fictitious names Nana and Lulu, therefore do not have a total guarantee of resistance to HIV1, and Lulu even has the certainty that cells with a functional CCR5 gene continue to be present in it. body. It is therefore susceptible to HIV1 infection. A little later, a second experience was to give birth to a boy. We don’t know anything more about him.

The world has condemned Jiankui He’s actions as totally irresponsible. In similar experiments, CRISPR-Cas9 can damage other DNA sites, causing unwanted side effects. Although Jiankui He claimed that testing the children’s hereditary information did not confirm such an error, experts agree that the analyzes performed were not sufficient to rule out DNA damage.

Jiankui He was guilty under Chinese law and given a three-year suspended prison sentence. Two out of ten of his colleagues were also sanctioned.

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