Yale University Mar 20 2025 Advances in the gene-editing technology known as CRISPR-Cas9 over the past 15 years have yielded important new insights into the roles that specific genes play in many diseases. But to date this technology - which allows scientists to use a "guide" RNA to modify DNA sequences and evaluate the effects - is able to target, delete, replace, or modify only single gene sequences with a single guide RNA and has limited ability to assess multiple genetic changes