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

Doing CRISPR gene editing while fetuses are in the womb could make it easier to treat inherited conditions, especially those affecting tissues such as the heart or muscles.

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