In a breakthrough, scientists have for the first time created embryos using human eggs that contain DNA from three parents, paving way to prevent 'designer' babies from inheriting rare genetic diseases.
Researchers from the Oregon Health and Science University in the US fertilised eggs containing DNA from two women to grow them into healthy embryos in a lab experiment.
The technique, designed for women with mutations in tiny structures known as mitochondria, can result in a range of devastating conditions including muscular dystrophy, 'The Telegraph' reported.
It involves taking chromosomes from the mother's egg, which carry 99.8 per cent of her DNA, and placing them in a donor egg which has healthy mitochondria but has had its own chromosomes removed.
The eggs were fertilised by sperm and almost half developed into healthy embryos.
The resulting children inherited 99.8 per cent of their DNA from their parents and a tiny fraction from the donor.
Researchers claimed that half of the embryos developed abnormally, but identified improvements in their technique which could improve its success rate.
The technique has already stirred a debate over its risks and ethics in the UK, where scientists did similar work a few years ago.
A team from Newcastle University successfully demonstrated a technique where the mother's DNA is transferred after the egg is fertilised and not before.
The Human Fertilisation and Embryology Authority is currently consulting on a change in the law which would allow the creation of IVF babies using either technique.
The Oregon researchers reported that tests of their technique on rhesus monkeys had shown it could create healthy offspring, but added that there were fewer issues with the quality of embryos in humans.