Why do gene editors want to treat fetuses while they are still in the womb?

Performing CRISPR gene editing while the embryos are still in the womb may make it easier to treat inherited conditions, especially those affecting tissues such as 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 amazing,” he says. “It opens up the opportunity to treat diseases that used to be very difficult to treat after birth.”