A controversial IVF procedure that uses the DNA of two women and one man has been approved in the United Kingdom after much consideration. The proposed mitochondrial transfer procedure, which has been opposed for years by critics who believe it could lead to the creation of designer babies, was granted approval on Thursday by Britain’s Human Fertilisation and Embryology Authority in the hopes that such a method will help prevent inherited and incurable mitochondrial diseases. Mitochondrial diseases are associated with symptoms including poor vision, diabetes, muscular dystrophy, and heart problems. Since women are responsible for contributing mitochondria to a baby, a woman with a mitochondrial disease or who is a carrier of faulty mitochondria could pass down the same or similar condition. The new procedure would involve adding healthy mitochondria from another female donor to the “nuclear DNA” from the mother and father. Although the review panel recommended the procedure’s use in very specific cases “where inheritance of the disease is likely to cause death or serious disease and where there are no acceptable alternatives,” critics of the procedure argue that its approval marks the beginning of genetically modified babies. The proposed method has already had its first success, albeit in another country where there aren’t rules on mitochondrial donation: a baby conceived in Mexico using the procedure was born earlier this year.