A startup company called Homology Medicines says it can edit genes without using CRISPR, and has even raised $127 million to develop treatments based on this idea, Technology Review says. The company says it uses viruses that are capable of repairing human genes on their own. If this is true, Tech Review says, Homology will have found the safest and simplest way yet to change genes in the human body, and without having to cut DNA.
But scientists are skeptical, and many tell Technology Review that they believe Homology's claims are probably wrong.
"What's surprising is this company raised so much money on something thought to be untrue in the scientific community," David Russell, a researcher at the University of Washington in Seattle tells the magazine. "I think there is just a gene-editing frenzy."
Homology's claim is that it can edit genes without adding a nuclease, and therefore without breaking the DNA strand. Russell himself was first to demonstrate the phenomenon in 1998, Tech Review says. If a DNA strand delivered by a virus closely matches a given gene it can sometimes swap in for it when a cell divides, and therefore a mutation can be replaced with a correct sequence.
The problem is that such virus-driven repairs happen very rarely and by chance, and the process isn't well understood. In some cell types only one in 1,000 cells are ever edited, Tech Review adds.
Homology says it has found a way to improve the pricess and has presented data at recent meetings, but Russell and other scientists tell Tech Review that the result is too good to be true. "Many of us in the audience were not convinced that what they were claiming were supported by the data they presented," Matthew Porteus, a gene-editing specialist at Stanford University who attended the talk and who works on CRISPR, tells the magazine.