There are still many technical issues – while the intended mutation occurred in one copy of the embryo, unexpected mutations occurred in others. By international agreement, the embryos are not viable and will not be used to create “super babies” (at least not yet). There are still ethical concerns regarding gene editing, and this is the perfect time for us writers to explore the implications, because like it or not it’s becoming our reality.
In your story gene editing could have cured most diseases, but at a price. Gene editing could create an opposition movement and international sanctions, or run away before anyone could stop it.