Scientists and security agencies are thinking hard about the safety of this sort of gene editingby Philip Ball / December 9, 2015 / Leave a comment
When engineer Theodore Maiman announced the first laser in 1960, reporters were quick to disclose the perils. “LA man discovers science fiction death ray”, announced the Los Angeles Herald. Four years later, Arno Goldfinger was threatening to emasculate James Bond with the new “weapon”.
Don’t be surprised if some Bond villain is soon holding the world to ransom with a “gene drive” that will spread a lethal poison across the globe in the bite of a mosquito. This is the latest nightmare invoked by biotechnology, thanks to the new ability to edit DNA with pinpoint precision. Of course, just because a danger features in a Bond movie doesn’t make it fantasy— plenty of movie villains have threatened nuclear apocalypse. Both scientists and security agencies are thinking hard about the safety of this sort of gene editing, and it’s right that they should. But right now, the perils of gene drives come more from inadvertent than malicious release into the wild.
Gene drives are one of the possibilities raised by the technique known as CRISPR-Cas9, a method for highly selective and efficient gene editing devised in 2012. This exploits a natural DNA-snipping enzyme called Cas9 to target and edit particular genes. The target sequence of the DNA is recognised by a matching sequence on an RNA molecule carried with Cas9. This enables a modified form of the gene to be pasted into a genome in place of the existing gene. In principle, CRISPR-Cas9 offers a very powerful way to cure diseases caused by mutations of one or a few specific genes, such as cystic fibrosis. Clinical trials of genetic therapeutics are not far off.
Proposals to use CRISPR-Cas9 to address human disease at the embryonic stage—to “correct” mutations in embryos—are controversial, however, because they would for the first time entail making inheritable changes to the genome, with consequences for future generations that are not yet known. Preliminary experiments on human embryos (not destined for development into fetuses) show that there may be complications (see my Prospect blog on this subject), for example owing to the tendency of the editing machinery to introduce changes elsewhere in the genome.