FIVE THINGS ABOUT CHEMICAL SURGERY

1 BREAKTHROUGH

Scientists have coaxed the faulty DNA of human embryos back into healthy code in an experiment that could be used to cure inherited diseases. In a world first, researchers in China corrected a single error in three billion letters of genetic code to remove the disease beta thalassaemia, a potentially fatal blood disorder. British scientists hailed the research as a “highly significant” advance in genetic editing.

2 THE FUTURE IS HERE

Prof. Darren Griffin of the University of Kent said: “For many years, we have been saying that direct gene editing in embryos is some way into the future. Now the future is here and there is much to consider.” The Chinese team said the approach could be used to fix similar inherited mutations. Previously, scientists have replaced genetic code with donor DNA using a technique called Crispr. But the new experiment is the first to target a single letter in genetic code.

3 THE SCIENCE

DNA is made up of four bases: adenine, cytosine, guanine and thymine, commonly known by A,C, G and T. Different combinations of these bases are what provide the instructions for every function in the human body.

4 THE CHINESE TEAM’S ACCOMPLISHMENT

The team showed it was possible to find the point mutation and target it with an enzyme that triggers a reaction that changes a G to an A, fixing the problem, although only one in five attempts was successful. The technique known as base editing was pioneered by David Liu of Harvard University, who referred to it as “chemical surgery.”

5 THE CAVEAT

Prof. Robin LovellBadge, from the Francis Crick Institute in London, said: “There would need to be far more debate, covering the ethics, and how these approaches should be regulated. It is far too early to even consider applying the methods clinically.”