Peter Attia· MD
but the challenge is that they weren't very efficient and it was also difficult to apply them uh to be able to treat the disease uh with sufficient amount of efficacy when chrisper came along um especially with cast 9 um it was much easier uh to be able to uh design strategies to to edit DNA and uh and and and that made it much more um feasible for many many groups to to really start to work on this idea