Using in-vitro fertilization techniques, scientists have successfully created an embryo with DNA material from three donor parents: nuclear DNA material from the mother and father, and mitochondrial DNA from a third party. The scientists hope that this approach will help eradicate genetic diseases of mitochondrial DNA in origin.

The Newcastle team have effectively given the embryos a mitochondria transplant. They experimented on 10 severely abnormal embryos left over from traditional fertility treatment.

Within hours of their creation, the nucleus, containing DNA from the mother and father, was removed from the embryo, and implanted into a donor egg whose DNA had been largely removed.

The only genetic information remaining from the donor egg was the tiny bit that controls production of mitochondria - around 16,000 of the 3billion component parts that make up the human genome.

The embryos then began to develop normally, but were destroyed within six days.

Full story from BBC News. See also an interview with University of Pennsylvania bioethicist Jonathan Moreno on the bioethics of this three-parent embryo.