A new approach to gene editing using the CRISPR/Cas9 system bypasses disease-causing mutations in a gene, enabling treatment of genetic diseases linked to a single gene, such as cystic fibrosis, certain types of sickle cell anemia, and other rare diseases. The method, developed and tested in mice and human tissue cultures by researchers at Penn State, involves inserting a new, fully functional copy of the gene that displaces the mutated gene.