Five years ago, researchers proved that they could perform microsurgery on genes, using a protein called Cas9 as a “scalpel”. This gene editing technique, known as CRISPR, set off an explosion of research, with scientists using it to manipulate specific genes in mice, rats, bacteria, yeast, zebra fish, fruit flies and plants. Now, the first trials of gene editing in human embryos are underway in China. Scientists there have reported manipulating the genes of embryos to make them resistant to the HIV virus and also have edited genes linked to the sickle cell blood disorder. Other trials have been approved in the US, and the Garvan Institute in Australia expects that these trials will really take off this year. This means that, in the future, we could be deleting – rather than treating – diseases.