Researchers Discover Hundreds of Unexpected Mutations from New Gene Editing Technology

For the past few years, a new scientific tool known as CRISPR-Cas9 has been hailed as the future of medicine. The technology, which has been the center of both extreme fascination and a bitter patent disputebetween two research groups, enables scientists to edit genomes. That is, they can remove harmful genes that cause diseases and replace them with normal genes that don’t—at least in theory. While exciting to many, the idea has also elicited fears that the technology could create dangerous mutations and be used in unbridled ways, for example in attempts to create superhumans and designer babies.

According to a new report, such fears may be well founded. The study, published in Nature Methods , found that using CRISPR-Cas9 to edit a genome can result in hundreds of unintended mutations being introduced. For the report, researchers sequenced the genomes of mice that had already undergone CRISPR-Cas9 procedures. They then scrutinized the edited genomes for any changes in the mouse genes—and they found plenty. The technology had accomplished the original intended task of correcting a gene that causes...