WIKIMEDIA, EKEMTo prevent the passage of mitochondrial disorders from mother to child, researchers have devised a clever solution: take the nucleus of a woman carrying harmful mutations in her mitochondrial DNA and transfer it to an enucleated egg of another woman without such defects. The hybrid egg, which carries the nuclear DNA of the mother-to-be and healthy mitochondria from the egg donor, can then be fertilized in vitro with sperm from the would-be father, and the resulting embryos implanted into mom.

The technique has proven successful in human cells in the lab, and has even resulted in the generation of seemingly healthy rhesus monkeys. But such three-way parenthood in vitro fertilization (IVF) is not without controversy, with many concerned scientists and citizens raising legal, ethical, and logistical issues. Next week (October 22), the US Food and Drug Administration (FDA) will meet in Silver Spring, Maryland, to discuss these...