CRISPR has been completely revolutionised this whole field and widened up the range of applications that you could use gene editing for. The big one is if you change genes in an embryo at a very early stage, then that will make those changes in every cell in the body. You're making a potentially permanent change to the human gene pool. And another thing that gets brought up sometimes is the idea that you could introduce changes aimed at enhancing a baby. Then you get into this whole design of baby territory and whether that's an appropriate thing to do or not. Although Christmas is very precise, it's not perfect, there's a risk that you could introducing unwanted changes as well as the ones