Genome editing is a rapidly developing practice through which an organism’s genetic code is deliberately changed. Many of the genome-editing approaches in development today involve a mechanism called CRISPR/Cas9, which is adapted from a genome-editing system that appears in bacteria (as a defense against viruses). CRISPR enables the relatively quick and efficient targeting of specific genes in a cell. Scientists are pursuing CRISPR-based therapies for potential use in humans, with aims such as removing disease-causing genetic mutations. Genome editing technology could ultimately play a role in the treatment of mental illness.