Of course gene editing has the potential to go very wrong, and will almost certainly go very wrong. But trisomy 31 is a well defined genetic defect with heavy consequences on the person having it and his or her entourage and there is no ethics preventing to correct the issue even if the technology used can be also used for nefarious means. It would be like not using dynamite for freeing miners in a collapsing mine because in the future there will be bombs made from dynamite targeting children.