- Broadly speaking, CRISPR-Cas9 technology functions by cutting out select sections of a genome and replacing it with new DNA sequences. However, while this type of technology can delete a faulty gene's function, it can be an imprecise and messy process. Editing a single letter in a genome has proved particularly challenging for researchers.
- Biochemist David Liu and post-doc fellow Alexis Komer, based at Harvard, have filed for a patent on their new invention, which allows the CRISPR-Cas9 editing tool to fix a point mutation without overreaching. A description of their efforts is published in the latest issue of Nature.
- As the majority of disease-associated gene variants are point mutations, the latest upgrade—a breakthrough that was two years in the making—has tremendous implications for treatments of many different diseases, including Tay Sach's, sickle cell anemia, cystic fibrosis and others.
Descriptions of gene editing using CRISPR-Cas9 can make the process seem straightforward. Take out the old, diseased gene and put the new healthy gene in. However, the process is not as clean as many people think. For one thing, cells respond to the gene-editing, and try to restore the integrity of the double-helix structure of the dismantled genes.
Liu and his team aimed to tame the process so the four components of DNA—A,T,C and G—could be individually deleted and replaced. By using an inactive version of Cas9, which would only latch onto DNA, but not cut it, the team was able to develop a system that can change C to T, and change G to A, but not any of the other 10 types of possible point mutations. This is a huge step forward, and Liu hopes to perfect this new system of editing with CRISP-Cas9.
Liu told Stat, "At least 3,000 inherited diseases are the result of a C that should be a T or a G that should be an A, including Franconi anemia and some cancers. And we’re in the middle of an all-out effort to do the other 10."
New innovations like this finding should help further the clinical applicability of CRISPR-Cas9 and make it a more targeted tool.