There are at least two other proteins that work similar to CRISPR as a homing system to find particular DNA sequences in the body (Talens & Zinc Fingers). The

There are at least two other proteins that work similar to CRISPR as a homing system to find particular DNA sequences in the body (Talens & Zinc Fingers). The big difference is that they're much slower and trickier on the R&D side - with CRISPR being slightly more complicated, but much faster to apply to your System of Interest. This is precisely why there is such a land-rush with CRISPR right now - it's easy to port to whatever system you're already working with. In fact, I'd likely predict that at the end of the day the CRISPR system is used to find the interesting therapies, but it will likely need to be 'hardened' into one of the above, older technologies to actually become a good deliverable therapeutic. CRISPR is inherently a 2-part system, where one of those parts would be really tricky to get the body to use reliably without error or screwing things up, whereas the older techs could effectively be delivered as a single genetic insert. It's just much harder to scan the search space with those older techs.