Eight babies born in UK with DNA of three to prevent genetic disease

Eight healthy babies were born in the UK using an experimental technique that combines the DNA from three people to prevent passing on devastating rare diseases from mothers to children, researchers said on Wednesday (Jul 16). The milestone method combines the egg and sperm from parents with a second egg from a donor woman. While the technique has been legal in the country for over a decade, its first proof has now surfaced, showing children born free of incurable mitochondrial disease, which is usually passed on from mothers.

The mitochondrial disease can result in severe disabilities and can also lead to death in some babies within days of being born. Couples who have a family history of such cases are at risk of the disease.

Children born through the new technique inherit most of their DNA, the genetic blueprint, from their parents, but also get about 0.1 per cent of it from the second woman. This brings a difference in what is passed down. This method is also allowed in Australia but not in many other nations like the US.

The latest research “marks an important milestone,” said Dr. Zev Williams, the director of the Columbia University Fertility Centre, who was not involved in the work. “Expanding the range of reproductive options... will empower more couples to pursue safe and healthy pregnancies.”

Scientists at Britain’s Newcastle University and Monash University in Australia reported in the New England Journal of Medicine on Wednesday that they performed the new technique in fertilised embryos from 22 patients. Following this, eight babies were born free of mitochondrial diseases. One woman is still pregnant.

While one of the right babies had slightly higher levels of abnormal mitochondria, it was not considered high enough to result in disease, said Robin Lovell-Badge, a stem cell and developmental genetics scientist at the Francis Crick Institute, who was not involved in the research. However, the baby should be monitored.

Lovell-Badge said the resulting baby would have no traits from the woman who donated the mitochondria as it makes up less than one per cent of the DNA of the baby. “If you had a bone marrow transplant from a donor... you will have much more DNA from another person,” he said.

Critics have earlier raised concerns that we can’t know the possible impacts of these techniques on future generations. However, advocates believe it could provide a promising alternative for some families.

In the UK, couples who seek babies born through the donated mitochondria technique need to get approval from the country’s fertility regulator. As of now, 35 patients have been authorised to undergo the new method.