"Unanticipated?" CRISPR is believed to be, at its core a bacterial immune system designed to 'knock out' problem viral genes by chopping them up at specific 'r

"Unanticipated?" CRISPR is believed to be, at its core a bacterial immune system designed to 'knock out' problem viral genes by chopping them up at specific 'remembered' loci and hoping that the lossy repair mechanisms cause mutations that prevent the gene from functioning. It also evolved to work on the fairly small genomes of single-celled organisms. So we've known for awhile that it's going to be quite tricky to get only the exact mutations that we want, at only the exact point that we want them. It's not magic.