DNA ‘chemical surgery’ could cure genetic diseases

SCIENTISTS have coaxed the faulty DNA of human embryos back into healthy code in an experiment that could one day be used to cure a range of inherited diseases.

Researchers in China have corrected a single error in three billion letters of genetic code to remove the disease beta thalassaemia, a blood disorder that can be fatal.

British scientists yesterday hailed the research as a “highly significant” advance in genetic editing, which could not only prevent diseases but also cure people living with inherited conditions.

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.”

Although the embryos were not implanted, 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, which acts like genetic scissors. But the new experiment is the first to target a single letter in the genetic code, known as a base.

DNA is made up of four bases: adenine, cytosine, guanine and thymine, known by the letters, A,C, G and T.

In beta thalassaemia, the disease is caused by a mistake in a single base – known as a point mutation.

The Chinese 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.

Prof David Liu, of Harvard University, who pioneered the technique, described it as “chemical surgery”.

The study, published in the journal Protein and Cell, was described as “ingenious” but scientists said it was still a long way off being used clinically.

Prof Robin Lovell-badge, from the Francis Crick Institute in London, said: “It is far too early to even consider applying the methods clinically.”