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EXPERT REACTION and MEDIA BRIEFING: First babies born in the UK through mitochondrial donation

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Peer-reviewed: This work was reviewed and scrutinised by relevant independent experts.

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Eight children in the UK have been born following a pioneering licensed IVF technique to reduce the risk of mitochondrial diseases, known as mitochondrial donation, according to a world-first report by Australian and UK researchers. The technique is designed to reduce the risk of mitochondrial DNA disease in children born to women who carry high levels of disease-causing mitochondrial DNA mutations. The UK was the first country to approve laws to allow the use of this groundbreaking IVF-based mitochondrial donation technology in 2015, followed by Australia, which passed Maeve's Law in 2022.

Journal/conference: New England Journal of Medicine

Research: Link to Paper 1 | Paper 2

Organisation/s: Monash University, Newcastle Fertility Centre, UK, Newcastle University, UK

Funder: Funded by NHS England and others.

Media release

From: Monash University

The UK report of the first babies born after mitochondrial donation provides hope for Australian families with mitochondrial DNA disease

The landmark publication today (7 am 17 July, AEST) of reports detailing the successful birth of eight babies in the UK after mitochondrial donation treatment is both a major development in the prevention of mitochondrial disease (mito) – and welcome news for the 120,000 Australians carrying disease-causing DNA variants that put them at risk of passing on this debilitating disease to their offspring.

The two papers published in the prestigious New England Journal of Medicine describe the reproductive and clinical outcomes of the world’s first clinical program in the application of mitochondrial donation. The program was run at the University of Newcastle UK and the Newcastle NHS Trust, and was led by Professor Mary Herbert and Professor Sir Doug Turnbull.

In these papers, the research team report the outcomes of 25 women who were at high risk of passing on disease-causing mitochondrial DNA and underwent mitochondrial donation. At the time of reporting eight babies have been born and there is one ongoing pregnancy. The mitochondrial donation procedure led to all babies having either undetectable or low levels of disease-causing mitochondrial DNA.

Professor Herbert, from both Newcastle University (UK) and Monash University’s Biomedicine Discovery Institute moved to Monash University in 2023 to help establish mitochondrial donation in Australia. This became a possibility in March 2022 when the Australian Senate passed legislation, known as Maeve’s Law, to allow the introduction of mitochondrial donation in Australia.

In Australia, approximately 60 babies born annually will go on to develop disabling and potentially fatal mitochondrial disease. There is no cure for mitochondrial disease and the only treatments available aim to manage the symptoms.

In 2023, the Medical Research Future Fund provided $15 million in funding for the mitoHOPE Program, piloting the introduction of mitochondrial donation into Australian clinical practice. The mitoHOPE Program’s clinical trial will be the first of its kind in Australia to determine the safety and efficacy of mitochondrial donation. Since late 2023, the Monash University team and its partners have been working closely with the National Health and Medical Research Council to gain a licence to train embryologists in mitochondrial donation, as a first step towards a clinical trial and clinical application of mitochondrial donation.

According to Professor John Carroll, Director of Monash’s Biomedicine Discovery Institute and head of mitoHOPE, the studies should give Australia momentum to follow suit.

“We hope to soon obtain our first licence from the NHMRC’s Embryo Research Licensing Committee, so that we can begin training our IVF embryologists in the procedure using donated eggs,” Professor Carroll said.

“The birth of eight babies with a greatly reduced risk of developing mitochondrial DNA disease provides hope for those waiting to access mitochondrial donation and shines new light on the path toward introducing mitochondrial donation in Australia. The mitoHOPE team aims to start recruiting into the clinical trial in about a year, but this is dependent on us gaining the necessary licences.

“The mitoHOPE Program would not exist were it not for the advocacy of the mito community and the funding provided by the Australian Government. We thank them for their continued support of and contribution to the mitoHOPE Program.”

Professor Herbert said the UK results have been a long time in the making. “It was enormously satisfying seeing a procedure that has been developed over two decades result in the birth of babies with a greatly reduced risk of developing mitochondrial DNA disease,” she said.

“The findings published give grounds for optimism. I look forward to continuing this work at Monash University and I hope that the new treatment can soon become available to Australian families affected by these devastating diseases.”

Professor John Christodoulou of Murdoch Children’s Research Institute and co-lead of the mitoHOPE clinical research team said the program is eager to hear from women with mitochondrial DNA disease who may be interested in participating in the clinical trial.

“The results from Newcastle provide considerable impetus to the mitoHOPE Program,” he said. “The clinical research team is working hard with members of the mito community to create the smoothest possible path to the clinical trial.”

The mitoHOPE Program is a research program and clinical trial hosted by Monash University and supported by the Australian Government’s Medical Research Future Fund. The program will pilot the introduction of mitochondrial donation in Australian clinical settings, once approval has been granted by the NHMRC’s Embryo Research Licensing Committee.

“These results give fresh momentum to Australia’s own mitoHOPE research program, which will deliver the world’s second ever clinical trial of mitochondrial donation,” Federal Minister for Health, the Hon Mark Butler MP said.

“The Australian Government is proud to be supporting this research.

“The mitoHOPE Program’s clinical trial will be the first of its kind in Australia, and only the second in the world. Cutting edge research takes time, and all relevant approvals and licences will need to be in place as safeguards before the clinical trial can proceed.”

Professor David Mackey AO is a Professor of Ophthalmology at the Lions Eye Institute and a Chief Investigator on the mitoHOPE Program. He has been studying the mitochondrial eye disease Leber Hereditary Optic Neuropathy (LHON) for 35 years. LHON is a devastating condition in which otherwise healthy people, usually teenagers or young adults, lose their central vision in both eyes due to disease-causing mitochondrial DNA. “Some people with Leber Hereditary Optic Neuropathy describe their stories as being ‘born with a bomb’ and don’t know which children are at risk of losing vision or when this will happen,” he said. “The success of mitochondrial donation shows we can defuse the bomb and allow families to live a normal life. The worry that one of them may suddenly go blind is lifted.”

Sean Murray, CEO of the Mito Foundation and a member of the mitoHOPE Executive Committee, welcomed the publication of the research. “We are now closer to accessing mitochondrial donation for Australians. We are fortunate to have Professor Mary Herbert, who led the scientific program in the UK, now working at Monash University so that Australians will benefit directly from what has been learnt in the UK,” he said.

“Congratulations to the families who have used these innovative techniques to reduce the risk of their children being impacted by mito. From my mito family to yours, thank you for pioneering this important technology.”

WHAT IS MITOCHONDRIAL DONATION

Mitochondria are present in almost all of our cells, providing the energy needed for each organ and tissue to function. Harmful mutations in mitochondrial DNA can result in reduced availability of energy, particularly affecting tissues that have high energy demands – for example heart, muscle and brain, collectively known as mitochondrial DNA disease. Because mitochondrial DNA is maternally inherited, mitochondrial DNA disease is passed from mother to child.

In the absence of a cure, attention has focussed on IVF-based technologies to reduce the risk of disease by reducing transmission of disease-causing mutations from mother to child. The Newcastle University research team led by Professor Mary Herbert has spent almost two decades developing and optimising the technique of mitochondrial donation by pronuclear transfer using fertilised human eggs. Learn more about mitochondrial disease and mitochondrial donation.

WHAT IS PRONUCLEAR TRANSFER:

The technique known as pronuclear transfer (PNT) is performed at 8-13 hours after the egg is injected with sperm. At this time the nuclear DNA from the egg and sperm are each contained in a large nucleus known as the pronucleus. The male and female pronuclei contained in the egg carrying a mitochondrial DNA mutation are transplanted to an enucleated egg donated by a woman who is free of disease-causing mitochondrial DNA mutations.

The resulting embryo inherits its parents’ nuclear DNA, but the mitochondrial DNA is inherited predominantly from the egg donor. The Newcastle team have previously reported findings from laboratory studies to optimise and investigate the safety and efficacy of PNT in human eggs.

PNT is made available to women for whom preimplantation genetic testing (i.e. testing the fertilised embryos for mitochondrial DNA defects) is unlikely to be effective. Preimplantation genetic testing is best suited to women likely to have embryos with low levels of mutated mitochondrial DNA.

Read the research paper: doi.org/10.1056/NEJMoa2415539

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Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Professor Lisa Hui is a maternal fetal medicine specialist at the Mercy Hospital for Women, a Professor in the Dept of Obstetrics, Gynaecology and Newborn Health at the University of Melbourne, and Group leader of Reproductive Epidemiology at Murdoch Children’s Research Institute

As an obstetrician involved in the Australian mitoHOPE clinical trial, I am very encouraged by the careful implementation of this reproductive care pathway, with comprehensive counseling and oversight. The results offer important new choices for prospective mothers with mitochondrial disease. At the same time, ongoing monitoring and data collection will be essential as mitochondrial donation moves into wider clinical use, especially regarding impacts on maternal health during and after pregnancy.

I was impressed by the rigorous clinical oversight and the thoughtful pre-assessment process in this study. It is important to note that not all women proceeded to mitochondrial donation, some because of their own health or fertility factors. This reminds us that the physical and psychosocial impacts of ART and pregnancy are not to be underestimated, particularly for women with chronic medical conditions.

Comprehensive pre-conception counseling and specialised antenatal care are essential with transformative treatments like mitochondrial donation.

The maternal outcomes in this study remind us that mitochondrial donation – and pregnancy itself - carries risks, especially for those with underlying mitochondrial disease. Careful monitoring is critical. Some unpreventable obstetric complications, such as identical twinning and placenta praevia, can add further risks to pregnancy for women with underlying medical conditions. Careful preconception assessment and counseling is essential for the responsible implementation of these advances.

Last updated: 16 Jul 2025 4:48pm
Declared conflicts of interest:
Co-investigator on the mitoHOPE clinical trial, chaired the mitoHOPE “Informed decision-making for pregnancy and parenthood working group”, and lead author on the working group’s literature review on pregnancy in women with mitochondrial disease (cited in this study). Funding – MRFF clinical investigator grant. Membership of the International Society for Prenatal Diagnosis. Advisory roles – Chair of the National Congenital Anomaly Advisory group to the commonwealth government (AIHW), and member of the Victorian Consultative Council of Obstetric and Paediatric Mortality and Morbidity

Dr Julian Koplin is a lecturer in bioethics at Monash University 

It is exciting to see early evidence that mitochondrial donation may be an effective way of increasing the reproductive options of those who are at risk of passing on mitochondrial disorders. These early results are encouraging, though it is important to note that they do not show that mitochondrial donation is risk free.

Mitochondrial donation's ability to broaden some women's reproductive options should be celebrated. However, it is important that mitochondrial donation continues to be seen as just one option among many, including potentially safer pathways that eliminate maternal mitochondrial DNA risk altogether, like donor egg IVF.

Last updated: 16 Jul 2025 2:46pm
Declared conflicts of interest:
None declared.
Dr Christopher Rudge is a Lecturer in Health Law from the Sydney Law School and Deputy Director of the Sydney Health Law Centre at The University of Sydney

This landmark UK study represents hopeful news for Australian families affected by mitochondrial disease. It provides long-awaited clinical evidence that mitochondrial donation can successfully prevent the transmission of these devastating conditions. However, this study also confirms that mitochondrial donation is a powerful risk-reduction strategy and not necessarily a perfect cure, as it shows some higher-than-expected mtDNA carryover and other health events in the children, even though causality between the treatment and those events was not established.
 
The study emerges at a pivotal moment for Australia. In 2022, the Commonwealth Parliament passed the Mitochondrial Donation Law Reform (Maeve’s Law) Act. This legal change created a narrow exception to the broad prohibition on genome editing, specifically to allow mitochondrial donation to be researched and administered under strict licensing conditions.
 
As reports of the Embryo Research Licensing Committee (ERLC) since 2022 show, no licence for the first clinical trial for mitochondrial donation has been issued in Australia. That is because the regulator is first building the detailed safety and ethical framework required to oversee the technology.
 
This UK data is essential as both a proof-of-concept and direct evidence to inform the safety protocols and long-term monitoring for Australia’s eventual trial participants.

Last updated: 16 Jul 2025 11:17am
Declared conflicts of interest:
None

Professor Mary Herbert is a Professor of Reproductive Biology at Monash University.  She also holds an appointment at Newcastle University and Newcastle Fertility Centre, UK. She is an author on the research.

As a reproductive biologist, I find it enormously gratifying that a new assisted reproductive technology can be used successfully to enable women with very high levels of disease-causing mitochondrial DNA to have children with a greatly reduced of developing the disease.
 
The findings give grounds for optimism. However, research to better understand the limitations of mitochondrial donation technologies will be essential to further improve treatment outcomes.
 
In previous lab-based research, we found that carryover of even a small amount of maternal mitochondrial DNA during the pronuclear transfer procedure can increase to very high levels in embryonic cell lines. 
 
For this reason, mitochondrial donation technologies are regarded as risk reduction treatments. Our ongoing research seeks to bridge the gap between risk reduction and prevention of mitochondrial DNA disease.
 
In the UK, mitochondrial donation treatment is performed within a strict regulatory framework under a licence granted by the Human Fertilisation and Embryology Authority. I hope that the successful outcomes reported today will help in navigating the rather complex regulatory system here in Australia.

Last updated: 16 Jul 2025 10:17am
Declared conflicts of interest:
Mary is an author of the research.  Mary is an author of the research.  Mary is an author of the research. 

Dr Eric Rubin is the Editor-in-Chief of The New England Journal of Medicine

These studies unite scientific rigor, clinical innovation, and deep ethical reflection to illustrate the full research continuum from bench to bedside. At the New England Journal of Medicine, we chose to publish this work in its full context, not only to highlight the outcomes, but also to surface the critical questions it raises about translating breakthroughs into patient care.

Where allowed by government regulations, this research has the potential to prevent serious inherited disease and gives parents truly meaningful new options for their children. Its publication also reminds us that preserving the infrastructure and integrity of biomedical research in the US and around the world is essential if we are to continue delivering such transformative treatments to patients.

Last updated: 16 Jul 2025 10:14am
Declared conflicts of interest:
Eric is the editor of the journal that published this research
Professor David Thorburn is Co-Group Leader, Brain and Mitochondrial Research at Murdoch Children's Research Institute and Honorary Professorial Fellow, Department of Paediatrics at The University of Melbourne

Mitochondrial donation was legalised in the UK in 2015 and in Australia in 2022. It was clearly a complex process in the UK to develop the approvals processes, the clinical and lab pathways, cope with delays from COVID-19 and accumulate sufficient outcomes to publish them without impinging on the privacy of the families involved.
 
So it is very exciting to see the first publications describing results for the first eight babies born in the UK program. The initial results demonstrate that the approach is effective in reducing the risk of having a child with mitochondrial DNA disease for women who are at high risk. For about three quarters of couples participating in the pronuclear transfer method, at least one suitable embryo was generated. About 40% of these couples had a baby and all were healthy and had undetectable or low levels of the abnormal mitochondrial DNA. Three babies had short-term symptoms that resolved and did not appear to relate to mitochondrial disease. All babies are developing normally to date, with the oldest 5 years of age.
 
The studies emphasise that longer-term followup needs to be performed, and the efficiency of the method could be further improved to achieve higher pregnancy rates. They demonstrate the value of offering the program in conjunction with other reproductive options, such as pre-implantation genetic testing, which can be effective in women with lower risk. I regard these results as very encouraging and supporting the ongoing development and use of mitochondrial donation in the UK and Australia.

Last updated: 16 Jul 2025 10:12am
Declared conflicts of interest:
David has declared he has no financial conflicts of interest and has the following unpaid positions:  Board Member of the Mito Foundation (the major relevant mito advocacy group) and he played a prominent role in their advocacy for legalising mitochondrial donation in Australia. He is also a Member of the MitoHOPE Executive, funded by the Medical Research Future Fund to deliver an Australian clinical trial of mitochondrial donation.

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