Revised Method Could Treat Various Diseases.

• Position: GENOME TECHNOLOGY - CRISPR/Cas9

A new version of the CRISPR/Cas9 genome editing technology that allows scientists to activate genes without creating breaks in the DNA--potentially circumventing a major hurdle to using gene editing technologies to treat human diseases--has been created by researchers at the Salk Institute for Biological Studies, La Jolla, Calif.

Most CRISPR/Cas9 systems work by creating double-strand breaks (DSBs) in regions of the genome targeted for editing or for deletion, but many researchers are opposed to creating such breaks in the DNA of living humans. As a proof of concept, the Salk group used its new approach to treat several diseases--including diabetes, acute kidney disease, and muscular dystrophy--in models.

"Although many studies have demonstrated that CRISPR/Cas9 can be applied as a powerful tool for gene therapy, there are growing concerns regarding unwanted mutations generated by the double-strand breaks through this technology' says Juan Belmonte, professor in the Gene Expression Laboratory.

In the original CRISPR/Cas9 system, the enzyme Cas9 is coupled with guide RNAs that target it to the right spot in the genome to create DSBs. Recently, some researchers have started using a "dead" form of Cas9 (dCas9), which still can target specific places in the genome, but no longer cuts DNA.

Instead, dCas9 has been coupled with transcriptional activation domains molecular...