The controversial three-parent technique, which allows parents with rare genetic mutations in mitochondrial genes to have healthy babies. The original method approved in the UK is called pronuclear transfer. It involves fertilizing both the mother’s egg and a donor egg with the father’s sperm. During early-stage embryos nucleus is removed from each fertilized eggs and nucleus from mother's fertilized egg is transplanted into donor cell. By doing this technique baby receives nuclear DNA from mother and father and mitochondrial DNA from donor. But the couple in above news had different approach called spindle nuclear transfer, where nucleus of fertilized egg was extracted and inserted to donor egg after removal of eggs nucleus. Procedure was perfomed by Dr John Zang.