Britain is planning to become the first country in the world to offer controversial "three-parent" fertility treatments to families who want to avoid passing on incurable diseases to their children.
The methods, currently only at the research stage in laboratories in Britain and the United States, would for the first time involve implanting genetically modified embryos into women, and raise serious ethical questions.
The techniques involve intervening in the fertilization process to remove faulty mitochondrial DNA, which can cause inherited conditions such as fatal heart problems, liver failure, brain disorders, blindness and muscular dystrophy.
They are designed to help families with mitochondrial diseases - incurable conditions passed down the maternal line that affect around one in 6,500 children worldwide. Mitochondria act as tiny energy-generating batteries inside cells,
The controversial potential treatment is known as three-parent in vitro fertilization (IVF) because the offspring would have genes from a mother, a father and from a female donor.
After a national public consultation showed Britons broadly favor the idea, the government's chief physician said on Friday it should be allowed to go ahead under strict regulation.
"Scientists have developed ground-breaking new procedures which could stop these diseases being passed on, bringing hope to many families seeking to prevent their children inheriting them," Sally Davies, chief medical officer, told reporters.
"It's only right that we look to introduce this life-saving treatment as soon as we can."
Davies said the government's health department is drafting regulations to cover the new treatments, and plans to publish them later this year. The move would make Britain the first country in the world to give patients to option of using so-called mitochondrial DNA transfer to avoid passing the diseases on to their children.
DNA SWAP
Scientists are researching several three-parent IVF techniques.
One being developed at Britain's Newcastle University, known as pronuclear transfer, swaps DNA between two fertilized human eggs. Another, called maternal spindle transfer, swaps material between the mother's egg and a donor egg before fertilization.
A British medical ethics panel which reviewed the potential treatments for mitochondrial diseases decided last year they were ethical and should go ahead as long as research shows they are likely to be safe and effective.
Because Britain is in the vanguard of this research, ethical concerns, political decisions and scientific advances here are closely watched around the world - particularly in the United States where scientists are also working on DNA swap techniques.
Some pro-life campaigners have criticized the scientific research, saying that creating embryonic children in a lab abuses them by subjecting them to unnatural processes.
Critics also worry that modifying embryos to avoid disease could be the first step towards the creation of "designer babies", whose genetic makeup could be modified as embryos to ensure certain traits such as height or hair color.
Asked whether she was "comfortable" with taking such a major step along the way to allowing human genetic modification, Davies said she had debated and considered the ethical implications with many experts over many years and had come to the conclusion the techniques should be allowed.
Any final decision on putting the regulations in place to allow the new treatments to be offered will be subject to a vote in parliament, but Davies said she hoped the first patients may be able to get the new treatments within the next two years.