New Delhi, July 17 -- Eight healthy babies were born in Britain with the help of an experimental technique that uses DNA from three people to help mothers avoid passing devastating rare diseases to their children, researchers reported Wednesday.

Most DNA is found in the nucleus of our cells, and it's that genetic material - some inherited from mom, some from dad - that makes us who we are. But there's also some DNA outside of the cell's nucleus, in structures called mitochondria. Dangerous mutations there can cause a range of diseases in children that can lead to muscle weakness, seizures, developmental delays, major organ failure and death.

Testing during the in vitro fertilization process can usually identify whether these mutations a...