Researchers have reported a method to prevent the inheritance of diseases caused by DNA mutations in mitochondria — cellular machinery that is passed down from mother to child through the egg cell.
A possible approach to this problem is to transfer the nucleus of an egg from a woman with mitochondrial disease into a healthy donor egg, but diseased mitochondria can still carry over into the resulting embryos. Hongying Sha and Jianhong Zhu at Fudan University in Shanghai, China, and their colleagues have come up with an alternative method. They transferred the nuclei of polar bodies — small germ cells that are created during the maturation of the egg and that have the same genome — into recipient eggs. The technique resulted in mouse pups with undetectable levels of donor mitochondria.
Polar-body transfer could one day be used to prevent mitochondrial disease, the authors suggest.