Inserting a new gene precisely into a desired genome location is challenging, with current technologies achieving very low efficiency.

“the Holy Grail would be to be able to insert the gene into anywhere you want uh precisely and also very efficiently and and today that ability is still not quite there yet uh we're still working on and many other groups are working on developing Technologies to make that happen uh with high enough efficiency uh we can do it now with very low level maybe less than a percent or maybe just single digit percent uh but for a big Gene that we're trying to put in uh we we don't have a good way to do that yet”