Why gene editors want to treat fetuses when they are still in the womb

Editing CRISPR genes while fetuses are in the womb could make it easier to treat inherited conditions, especially those that affect tissues like the heart or muscles.

Kiran Musunuru of the University of Pennsylvania and his colleagues tested gene editing in monkeys and found that it was much more effective when given before birth. “What we found was surprising,” he says. “It opens up the possibility of treating diseases that have been very difficult to treat after birth.”