Multiple sgRNAs with overlapping sequences enhance CRISPR/Cas9-mediated knock-in efficiency

Genome editing: Improving efficiency by improving DNA repair A method to improve the efficiency of repairing double-stranded DNA breaks facilitates the production of animals with edited genomes. The CRISPR/Cas9 system has been revolutionising biomedical research as it allows the insertion or deletion of any DNA sequence at specific sites by making double-strand DNA breaks. However, the insertion of precise genetic changes is limited by the relatively low efficiency of the repair mechanism, which requires a template DNA molecule to promote error-free repair of the DNA strands. A team of South Korean scientists led by Su Cheong Yeom at Seoul National University and Han Woong Lee at Yonsei University show that delivering multiple overlapping single-guide RNAs (that share at least five base pairs of the target sequence) as a DNA template significantly improves the repair and thus the production of mice with a targeted gene insertion.