A world where DNA can be rewritten to fix deadly diseases has moved a step closer after scientists announced they had genetically edited the cells of a human for the first time.
A man in China was injected with immune cells which had been modified to fight his lung cancer. Larger trials due to take place next year in the US and Beijing could open up a new era of genetic medicine, scientists say.
The technique used, called Crispr, snips away genetic code and replaces it with instructions to build better cells.
Professor Andrew Sharrocks, of the faculty of biology, medicine and health at the University of Manchester, said the technique could help in treating cancer "but also potentially combating auto-immune type diseases including arthritis".
He added: "The potential for using this technology in the medical sphere is high and potentially transformative."
In the case of the Chinese man, scientists led by Dr Lu You at Sichuan University in Chengdu focused on a gene which holds the instructions to build a protein called PD-1. The protein works like an antenna, looking out for healthy cells, so that the immune system knows not to attack them. However, cancer masquerades as a healthy cell, which is why it is often so deadly.
The scientists took immune cells from the man's blood and altered their DNA to remove the antennae, before increasing them in a lab and injecting them back into the man's bloodstream. Experts say it is effectively like cutting the brakes on the immune system.
Doctors will monitor the man's progress over the next six months.
Dr Carl June, of the University of Pennsylvania in Philadelphia, is planning a cancer trial in the US next year, while Peking University is planning more Crispr trials in March next year.
Dr June told the journal Nature the race between the US and China to get gene-edited cells would be like "Sputnik 2.0".
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