Eight Babies Born Free of Mitochondrial Disease Thanks to Pioneering Three-Person IVF

Developed to prevent the transmission of devastating mitochondrial diseases, this method offers a lifeline to families affected by these inherited conditions.

Mitochondrial disease, passed down exclusively from mothers, can severely impair the body’s ability to produce energy. This can lead to serious symptoms, including muscle weakness, brain damage, organ failure, and in some cases, early infant death. Around one in every 5,000 babies in the UK is born with a mitochondrial disorder, and for affected families, the emotional toll is profound.

The technique involves using genetic material from three people, both parents and a female donor. Scientists combine the nuclear DNA of the intended mother and father with healthy mitochondrial DNA from a donor egg. The result is a child who carries 99.9% of their DNA from their parents, with a small fraction, approximately 0.1%, coming from the donor. This tiny addition can be the difference between life and death for children at risk of mitochondrial disease.

The procedure has been legal in the UK for nearly a decade, but these eight births, four boys and four girls, including a set of twins, represent the first successful outcomes of the approach. One further pregnancy is currently ongoing. All the babies born so far are free of mitochondrial disease and are developing as expected.

The technique was pioneered at Newcastle University and implemented at the Newcastle Fertility Centre. Fertilisation is performed in a laboratory where eggs from both the mother and donor are fertilised with the father’s sperm. Scientists then transfer the parents’ DNA into an embryo that contains the donor’s healthy mitochondria, effectively preventing the inheritance of the defective genetic material.

Twenty-two families have now undergone the procedure through the NHS Highly Specialised Service for Rare Mitochondrial Disorders. Though still closely monitored, the outcomes so far are encouraging. One child developed epilepsy, which resolved on its own, and another was treated for an irregular heartbeat, neither of which are believed to be linked to mitochondrial issues.

In five of the eight births, no faulty mitochondria were detected at all. In the remaining three cases, a small proportion, between 5% and 20%, of defective mitochondria were found in biological samples. However, these levels are well below the threshold typically associated with disease. Researchers continue to study why any carryover occurred and how to eliminate it entirely in future treatments.

While mitochondrial replacement therapy represents a dramatic leap forward in preventing inherited disease, it also raises ethical and scientific questions. Because mitochondria contain their own DNA, this technique results in children carrying genetic material from three people, a contentious issue. Critics warned of a slippery slope toward genetically modified “designer babies.” However, proponents may argue the benefits in preventing suffering outweigh the theoretical concerns.

The UK was the first country to approve the legal use of this procedure, following a vote in Parliament in 2015. It remains the only nation where the technique has been translated into clinical practice with this level of oversight and success.

For families affected by mitochondrial disorders, the news brings hope. Many have faced repeated loss, uncertainty, and fear. The successful births mark not just a scientific triumph, but an emotional one, giving families the chance to raise healthy children and break the cycle of inherited disease.