Such controversial procedures should only be allowed if they are proven safe, the Nuffield Council on Bioethics said Tuesday, but its advice seems likely to reignite debate. Currently, such treatments are only allowed for research in the U.K., and British law forbids altering a human egg or embryo before transferring it into a woman.
In 2008, when British scientists first announced they had created embryos using the method, news headlines trumpeted the idea of a child having three parents — two biological mothers and a father.
But scientists say that only trace bits of genetic material would come from one of the women.
The procedure involves using an egg from one woman with mitochondrial defects and the sperm of her partner. Scientists then put that embryo into an emptied egg from a second woman with healthy mitochondria. Only trace amounts of a person's genes come from the mitochondria, and experts said it would be wrong to say the embryos have three parents.
"If these novel techniques are adequately proven to be acceptably safe and effective as treatments, it would be ethical for families to use them," the report said. The authors couldn't say when the techniques might be ready, but thought it would take several years.
The mitochondria are a cell's energy source and are contained outside the nucleus in a normal female egg. Mistakes in the mitochondria's genetic code can result in serious diseases such as muscular dystrophy, epilepsy, heart problems and mental retardation. About one in 6,500 children in Britain is born with a serious mitochondrial disorder.
Some activists warned that allowing the new methods would be one step away from allowing genetically modified babies.
"The techniques are unnecessary, and research on them is a waste of taxpayers' money because safe and effective techniques already exist," David King, director of Human Genetics Alert, said in a statement. The group is a secular organization that opposes many genetics and fertilization experiments. King compared the technique to Frankenstein's creation.
Other experts said the research was intended only to help parents have healthy children.
"We have an opportunity to allow women with mitochondrial (problems) to become mothers without facing the agonizing possibility of passing their condition onto their child," Marita Pohlschmidt, director of research at the Muscular Dystrophy Campaign, said in a statement. She urged the government to move quickly to develop the treatment so that it could be used as soon as possible.