Controversial 'CRISPR babies' have genetic mutation linked to risk of early death

Modesto Morganelli
Giugno 7, 2019

Last November, Chinese researcher He Jiankui stunned the world when he announced the birth of twin girls whose genomes were altered before birth using CRISPR gene-editing techniques. He took the extraordinary step of performing genetic modification on human embryos with the intention of having them carried to term. He glossed over these concerns, making his experiment the subject of worldwide outcry. One of the twin babies was reported to have one copy of CCR5 modified by CRISPR-Cas9 gene editing, while the other baby had both copies edited.

What he tried was target a gene called CCR5. In other words, he had created edits with no known precedent.

Once edited, the embryos were implanted into the mother's uterus.

The resulting girls - known as Lulu and Nana - were born a year ago. Their analysis indicated a higher mortality rate for those with two mutated CCR5 genes.

Scientists from UC Berkeley searched a repository of human subjects' DNA to look for the same variants of the CCR5 that He Jiankui gave the kids, NPR reports. The researchers compared death records and genomic profiles in the UK Biobank database. Now, a study conducted in University of California, Berkeley says that the gene mutation that was done in the genomes of the twin babies is associated with 21% increase in mortality in later life. The study's authors suggest this could be because CCR5 modifications are also linked to higher susceptibility to viruses such as West Nile and influenza.

Even if a mutation might not be beneficial for people who are healthy, in people who are infected with HIV, "there's clearly a positive effect" when a mutation is introduced, said Nielsen.

The new study "doesn't show anything about the effects of the mutation per se, but what it does show is an overall effect on mortality", said Nielsen.

Experts said, Prof He's actions were "very dangerous" and "foolish". He was sacked from his job at the Southern University of Science and Technology in January, and publicly, the Chinese government condemned his research.

He was subsequently suspended from any scientific activities amid mounting criticism at home overseas about the experiment.

The Nature Medicine study highlights another of the many reasons why He's use of CRISPR on viable human embryos was so ill-advised.

"Ramsus Nielsen, the co-author of the study said -" Beyond the many ethical issues involved with the CRISPR babies, the fact is that, right now, with current knowledge, it is still very unsafe to try to introduce mutations without knowing the full effect of what those mutations do", said Rasmus Nielsen, a UC Berkeley professor of integrative biology.

"The fact is that right now, with current knowledge, is still very risky to try to introduce a mutation without knowing the full effects of these mutations on the organism", said Professor Rasmus Nielsen.

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