Mitochondrial donation: the pioneering IVF treatment giving families hope

Mitochondria are tiny structures inside our cells that act like batteries, powering everything we do. Their work is defined by a small amount of special DNA that mitochondria carry. But when they don’t work properly, the results can be life-changing.

We inherit our mitochondria from our mothers. And if there are faults in the mitochondrial DNA, they can be passed on too.

Mitochondrial disease is the rare inherited condition caused by these faults. Around 1 in 5,000 babies are born each year with faulty mitochondrial DNA that can lead to severe disability and, in many cases, early death. There is no cure.

Families with a history of the disease are therefore left with tough choices if they want to try to have children.

Mitochondrial donation – also known as mitochondrial replacement therapy – is a cutting-edge IVF technique pioneered by researchers at Newcastle University and the Newcastle upon Tyne Hospitals NHS Foundation Trust. There are two approaches based on the principle of transferring the nucleus from the mother’s egg with faulty mitochondria into a donor egg with healthy mitochondria.

The latest research focuses on one approach called pronuclear transfer, where both the mother’s egg and donor egg are fertilised prior to the nuclear material being transferred from the mother’s egg to the donor.

The result is an embryo with egg and sperm DNA from the parents and a tiny amount of mitochondrial DNA from the donor – less than 1% of the total genome.

Research into the technique raised the possibility of affected families having genetically related children they knew were at low risk of mitochondrial disease. But it also came with complex ethical and legal questions. Could this be done safely? Should it be allowed? And how could public trust be earned?

Wellcome has supported work on mitochondrial donation from the very beginning. We’ve funded discovery research in Newcastle for over 30 years, with early grants to Professor Doug Turnbull – who led much of this work – dating back to the mid-1990s.

Along that journey, we’ve contributed to several major milestones, including:

• funding the Wellcome Centre for Mitochondrial Research at Newcastle University, where the technique was developed
• supporting public engagement and ethical discussions to ensure the science was grounded in people’s real concerns and values
• working with policy makers, regulators and researchers to help shape the UK’s legal framework – making the UK the first country in the world to approve mitochondrial donation in law in 2015
• co-funding the clinical trial to assess the safety and effectiveness of the treatment

We continue to fund a wide range of research into mitochondria and their connections to health, including mitochondrial disease. And we continue to push for policy to keep pace with scientific innovation across a range of emerging issues.

In 2023, the Human Fertilisation and Embryology Authority (HFEA) confirmed that between one and five babies had been born in the UK through mitochondrial donation.

And in July 2025, researchers published a paper in the New England Journal of Medicine showing for the first time that the treatment was effective. Eight children have now been born through mitochondrial donation. But most importantly, so far, all are healthy.

An accompanying paper in the New England Journal of Medicine shares definitive detail on the technique, realising decades of scientific discovery. It also shows how specialised genetic testing carried out during IVF can be used prior to mitochondrial donation as an integrated programme of care that overall reduces the risk of mitochondrial disease in families at high risk.

As with many breakthrough technologies, there are still questions to answer. There’s evidence that some mitochondria are carried over to the donor egg, resulting in very low levels of DNA faults being detected in some babies. Ongoing monitoring of the children born through mitochondrial donation will be necessary to understand their future health.

But right now, for the families involved, this is life changing.

“As parents, all we ever wanted was to give our child a healthy start in life,” says the mother of a baby girl born following mitochondrial donation.

“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.”

For the wider world, this is a glimpse of what’s possible when science, policy and lived experience come together.

“This is a remarkable scientific achievement, which has been years in the making and we are overjoyed for the families of the eight children born so far,” says Beth Thompson, Executive Director for Policy & Partnerships at Wellcome.

“The UK has led the way and has demonstrated the importance of science grounded in close and careful co-ordination between researchers, funders and regulators – and, very importantly, working closely with families affected.

“As the science progresses, we will continue championing brave investment in science and for policy and regulation to keep pace. The success of this research should inspire us to move forward on other updates, opening the way for further innovation."