British fertility regulator says handful of 'three-parent' babies born

May 10 (UPI) -- A handful of babies with the DNA of a man and two women have been born in Britain using a technique that aims to prevent parents from passing diseases on to their children.

The Mitochondrial Donation Treatment program at Newcastle University has resulted in the birth of "less than five" babies the Human Fertilization and Embryology Authority said Tuesday in response to a freedom of information request.

HFEA refused to provide the actual number of babies over fears it "could lead to the identification of a person to whom the HFEA owes a duty of confidentiality," while the university has a policy of not releasing any information regarding MDT births.

MDT is an in vitro fertilization technique that transfers the nuclear genetic material from the carrier female's egg into a donor woman's egg from which the nuclear material has been removed leaving only the mitochondrial genes. The eggs are then fertilized with sperm to create healthy embryos free from the mutations their mothers carry.

Mitochondria -- "batteries" inside every cell that convert food into energy -- are inherited solely from mothers and can result in abnormal mutations being passed onto all babies of a "carrier" woman. Mitochondrial disease affects about one in 6,000 children.

The resulting incurable diseases, causing brain damage, muscle wasting, heart failure and blindness, often kill newborns within days, and for families that have lost children to mitochondrial disease MDT may be their only hope.

Britain is the only country in the world to regulate the procedure, according HFEA, leaving only "limited evidence on risks and success rates" available.

"Only people who are at a very high risk of passing a serious mitochondrial disease onto their children are eligible for treatment," HFEA says on its website, cautioning that people with less serious forms of the disease may not be eligible.

All requests for MDT require approval from the regulator on an individual, case-by-case basis.

In 2017, researchers at Newcastle University were awarded the first license to perform the technique, which was legalized by parliament in 2015, although it has been carried out elsewhere in the world.

A team led by the New York New Hope Fertility Center's John Zhang created the first successful three-person embryo in 2016 leading to the birth of a healthy baby, although they had to relocate the medical team to Mexico to carry out the procedure because it is not authorized in the United States.

Research published in February in the journal Fertility and Sterility found that reversal was a risk in some instances -- where a very small number of abnormal mitochondria that are unavoidably transferred from the mother's egg to the donor egg begin to grow when once the embryo is in the womb -- but did not conclude why it occurred only in some cases.