First ‘three-parent' babies found healthy in scientific breakthrough

Telegraph

16-07-2025

Eight healthy babies with the DNA of three people have been born in Britain in a groundbreaking first hailed as a 'scientific tour-de-force.'
Dubbed 'three parent babies', the infants carry the genetic material of a 'second mother' to repair damage in their mitochondrial DNA, which powers the cells.
British scientists have spent decades perfecting the technique, which involves transplanting nuclear DNA – containing all the characteristics of a person – into a donor egg with healthy mitochondria.
Scientists hope the breakthrough can help women whose children would be at risk of mitochondrial disease.
Every year around one in 5,000 children are born with mitochondrial mutations in Britain, while 12,000 are living with a mitochondrial disorder.
These can lead to serious problems such as heart and liver failure, blindness, deafness, diabetes, respiratory problems and even death.
After following the infants for up to two years, scientists announced on Wednesday that the technique works and all the babies are healthy.
Professor Sir Doug Turnbull, Emeritus Professor of Neurology, at Newcastle University, who led the team said: 'I think everybody knows I'm a natural pessimist, so it's a relief.
'Mitochondrial disease can have a devastating impact on families. Today's news offers fresh hope to many more women at risk of passing on this condition who now have the chance to have children growing up without this terrible disease.'
The disease is passed down solely from the mother, and there is no cure, but in the late 1990s, scientists began to question whether the defective mitochondria could be replaced with healthy donor DNA.
While nuclear DNA is the blueprint for the entire cell, comprising around 3.3 billion base pairs, mitochondrial DNA only codes for energy production and is built from around 16,000 base pairs.
Nevertheless, the idea proved controversial, with both the Church of England and the Catholic Church in England and Wales questioning whether the technique was safe or ethical.
Experts from the Zoological Society of London warned that in 50 per cent of animal studies, faulty mitochondrial DNA had been transferred over during the procedure, while the US Food and Drug Administration deemed the process unsafe.
In spite of the objections, Parliament approved new legislation to allow the procedure in 2015, and the first licence was granted in 2017 to Newcastle Fertility Centre, which pioneered the technique.
The procedure involves transplanting the nuclear DNA - which contains all the genes that make up individual characteristics –from a fertilised egg to an egg donated by an unaffected woman which has had its nuclear DNA removed.
The resulting embryo inherits its parents' nuclear DNA, but the mitochondrial DNA is inherited predominantly from the donated egg.
Early attempts failed and it was not until 2023 that Freedom of Information requests showed the first baby had been born in Newcastle by these methods.
At the time, researchers were reluctant to discuss the case, leading to fears the child had not survived.
Now, two years on, scientists say the infant is growing well and has passed all developmental milestones. Seven other children have also been born through the process without any major complications, and all eight babies show no signs of having mitochondrial DNA disease.
Prof Bobby McFarlane, Professor of Paediatric Mitochondrial Medicine at Newcastle University said: 'All the children are well and they are continuing to meet their developmental milestones.
'While longer term follow-up of children born following mitochondrial donation is of paramount importance, these early results are very encouraging.
'Seeing the joy and relief these children have brought to their parents is such a privilege.'
Life and possibility
The parents did not want to be named but said they were 'overwhelmed with gratitude', and thankful to the scientists who allowed them to conceive healthy children.
One mother of a baby girl born following mitochondrial donation said: ' After years of uncertainty this treatment gave us hope –and then it gave us our baby.
'We look at them now, full of life and possibility, and we're overwhelmed with gratitude. Science gave us a chance.'
The mother of a baby boy added: 'This breakthrough has lifted the heavy cloud of fear that once loomed over us. Our little family is complete.'
Scientists hope the breakthrough can help around 150 women a year.
Unlike with egg or sperm donors, children are not entitled to know the details of their mitochondrial donor unless they have agreed to share the information. However in some cases friends or family members have donated their DNA.
Commenting on the research Dusko Ilic, Professor of Stem Cell Science, King's College London, said the healthy births were 'a remarkable accomplishment'.
Dr Andy Greenfield, Honorary Fellow at the Nuffield Department of Women's & Reproductive Health at the University of Oxford, added: 'It is a triumph of scientific innovation in the IVF clinic – a world-first that shows that the UK is an excellent environment in which to push boundaries in IVF.
A baby was born in 2016 in Mexico using a similar technique developed by British researchers, but it is not known if the child survived.