Can gene editing kill deadly diseases?

Two clinics sit adjacent to one another in a new hospital in a medium-sized city in the developed world.

In one, a family waits for a long-scheduled appointment. Their daughter suffers from a rare inherited disease. One of her genes encodes for a protein that doesn’t perform its functions normally, and her degenerative ailment is most likely fatal. Their doctor is about to discuss a procedure that will remove cells from the affected organ, correct the inherited faults and reinfuse her cells, allowing her organ to perform its functions without the inborn errors that she and her family have been managing since her birth.

The procedure is expensive, requiring a payment plan over a decade financed by a start-up, and it will need chemotherapy and a hospital stay. But it’s a one-time fix, and if side-effects appear down the line, doctors will study them.

In another waiting room, a soon-to-be-expectant couple waits to meet a geneticist. The doctor will present a plan for their unborn baby: to alter a few lines of its DNA to reverse a rare disorder before...