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This groundbreaking ‘surgery’ on human embryos successfully cured a genetic disease

For the first time, scientists have shown they can cure genetic diseases with targeted ‘chemical surgery’ — by carefully editing out one error among the three billion components that make up the genetic code.
For the first time, scientists have shown they can cure genetic diseases with targeted ‘chemical surgery’ — by carefully editing out one error among the three billion components that make up the genetic code. Creative Commons

Scientists in China have successfully used “chemical surgery” on human embryos to remove disease for the first time — a breakthrough that could one day help treat or even prevent a host of inherited diseases.

“For many years, we have been saying that direct gene editing in embryos is some way in to the future,” Darren Griffin, a geneticist at the University of Kent, told The Guardian. “Now the future is here and there is much to consider.”

Specifically, Griffin suggested that the breakthrough opens a Pandora’s box of ethical questions and safety concerns over manipulating genes in embryos.

But regardless, the “chemical surgery” is an extremely important advancement, Griffin said. That’s because the Chinese researches used precise and targeted “base editor” techniques to zero in on one mutant gene among billions of genetic components, and then selectively fix that gene.

“We are the first to demonstrate the feasibility of curing genetic disease in human embryos by base editor system,” Junjiu Huang, one of the Sun Yat-sen University researchers, told the BBC.

The scientists performed the “chemical surgery” on lab-made embryos, BBC reports, removing a blood disorder called beta-thalassemia.

By using a “base editing” technique, they could change the fundamental blocks that create the genome: adenine, cytosine, guanine and thymine — often known by the letters they begin with, A, C, G and T.

In the case of beta-thalassemia, the disease is caused by an error in which an A is instead a G. To fix the error, the Chinese scientists flipped the G back to an A — curing the disease.

And scientists say that could help come up with ways to treat patients with that disease — “and even other inherited diseases,” Huang said.

The embryos were not used to produce babies, The Guardian reports.

Base editing has real potential, particularly given how few mutations it usually takes to cure a disease, according to Harvard University Professor David Liu.

“About two-thirds of known human genetic variants associated with disease are point mutations,” Liu told the BBC. “So base editing has the potential to directly correct, or reproduce for research purposes, many pathogenic [mutations].”

Base editing is an improvement on an earlier form of gene editing called Crispr. A drawback of Crispr was that it cut through the entire double strand of a DNA helix — whereas base editing can simply alter individual letters in the code.

Liu told the BBC that base editing, or “chemical surgery,” has fewer negative side effects than Crispr.

But don’t get too excited: It could be a while before base editing comes to a hospital near you.

“While this is undoubtedly a highly significant advance, it is important not to get carried away about its widespread utility if put into clinical practice,” Griffin, the geneticist, told The Guardian. “An embryo would still need to be diagnosed as abnormal, then the base editor applied, then re-diagnosed to make sure that it had worked. This would be an involved procedure that would be very expensive.”

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