CRISPR/Cas faces the bioethics spotlight.

Three years ago, Jennifer Doudna and Emmanuelle Charpentier launched a molecular biology revolution by unraveling the CRISPR/Cas system. Their seminal paper, published in June 2012 and cited over 900 times according to Google Scholar, describes a mechanism by which the Cas9 enzyme can cleave any segment of DNA, guided by a short RNA molecule complementary to the sequence of interest. Scientists quickly took note and have since exploited the finding to rewrite the genomes of cultured cells and model organisms, tweak gene expression programs, and drive drug development and disease etiology research.