![\"mGluR5](\"\/\/media.nature.com\/w700\/magazine-assets\/d41586-018-05545-8\/d41586-018-05545-8_15876804.jpg\")
<\/div>\n<\/div>Expression of a protein (blue-green, left) associated with fragile X syndrome is suppressed (right) in the brains of mice treated with CRISPR gene-editing molecules. Credit: B. Lee\u00a0et al.<\/i>\/Nat<\/i>ure<\/i>\u00a0Biomed. Eng.<\/i><\/p>\n<\/figcaption><\/figure>\n \n<\/header>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/article>\n<\/div>\n <\/p>\n <\/p>\n Scientists are mining gold for new ways to treat diseases in the brain.<\/p>\n The gene-editing system CRISPR\u2013Cas9 holds promise as a tool to counteract mutations associated with disease. But the system\u2019s key molecules are usually delivered by viruses, which can trigger side effects.<\/p>\n As a non-viral alternative, Hye Young Lee at the University of Texas Health Science Center at San Antonio, Niren Murthy at the University of California, Berkeley, and their colleagues tested a new version of CRISPR\u2013Cas9. Called CRISPR\u2013gold, it uses gold nanoparticles rather than viruses to deliver gene-editing molecules. The researchers injected CRISPR\u2013gold into two brain areas in mice and found that the system edited genes in several major cell types.<\/p>\n The researchers tried the technique on genetically engineered mice that are a model for fragile X syndrome, a genetic condition associated with autism-spectrum disorders. CRISPR\u2013gold quieted the overactive gene linked to the syndrome and suppressed the animals\u2019 abnormally repetitive behaviours.<\/p>\n <\/p>\n<\/div>\n