Last updated July 17, 2018 at 10:14 am
Gene editing technique may be less accurate than hoped
The gene editing technique CRISPR-Cas9 has been widely hailed as a promising therapeutic strategy for diseases such as cancer, HIV, haemophilia and sickle cell disease.
However, questions are now being raised after a UK study found that it appears to edit DNA near the genes being targeted as well as the genes themselves.
Researchers from the Wellcome Sanger Institute looked at mouse and human cells and found that sections of DNA, some several thousand DNA letters long, had been deleted, while others had been rearranged.
The experiments were not designed to detect deleterious effects of the chromosomal changes beyond knockout of the target gene, so the relevance of the findings to clinical applications of Cas9 is unknown. However, the researchers say they highlight a potential safety concern that warrants further study.
Cas9 works by cutting the two strands of cellular DNA at a target site within the genome. Cells repair these breaks through pathways that often introduce small DNA insertions or deletions. This process can be harnessed to inactivate disease-causing genes, or correct genetic mutations.
Previously, safety concerns have mainly arisen from the low likelihood that Cas9 will cut the genome at sites other than the intended target.
The paper published in Nature Biotechnology.