Precise "chemical surgery" has been performed on human embryos to remove disease in a world first, Chinese researchers have told the BBC.
Base editing alters the fundamental building blocks of DNA: the four bases adenine, cytosine, guanine and thymine.
Junjiu Huang, one of the researchers, told the BBC News website: "We are the first to demonstrate the feasibility of curing genetic disease in human embryos by base editor system.".
The experiments were performed in tissues taken from a patient with the blood disorder and in human embryos made through cloning.
He told the BBC: "About two-thirds of known human genetic variants associated with disease are point mutations.
The research group at Sun Yat-sen University in Guangzhou hit the headlines before when they were the first to use Crispr on human embryos.
The study, published in Protein and Cell, is the latest example of the rapidly growing ability of scientists to manipulate human DNA. »