Biotechnology

Doctors will use a cutting-edge IVF technique to help two couples have healthy babies.

The news: British regulators have approved the first uses of a technique called mitochondrial replacement therapy in the UK. The approach will use DNA from three people—the parents and a female donor—to avoid passing on a devastating neurodegenerative disorder caused by faulty mitochondria.

How it works: Doctors fertilize a woman’s egg with sperm and remove its nucleus, leaving the defective mitochondrial DNA behind. They then inject the nucleus into a hollowed-out donor egg containing only healthy mitochondrial DNA.

US opposition: It’s unlikely the US will follow Britain’s lead anytime soon. Congress has effectively barred research that involves implanting modified embryos in a person. New York fertility doctor John Zhang had to go to Mexico to perform a similar procedure, which resulted in the birth of a seemingly healthy baby boy in 2016.