In a major breakthrough, scientists in Britain have successfully used a technique known as mitochondrial donation to prevent mothers from passing on rare mitochondrial diseases. The result? Eight healthy babies—four boys and four girls, including a set of identical twins—have been born completely free of these inherited conditions. The procedure, sometimes called “three‑person IVF,” combines nuclear DNA from the parents with mitochondria from a healthy donor to create embryos without the faulty mitochondrial genes.
Until recently, mitochondrial diseases, caused by mutations in the little energy‑powerhouses outside our cell nuclei, had no cure. In the UK, about one in 5,000 babies are born with such conditions, which can lead to muscle weakness, organ failure or neurological issues. Now, reports from The Associated Press confirm this is the first time healthy births have been achieved in a full-scale clinical setting after the UK legalised mitochondrial donation in 2016.
A scientific first, a lifeline for families
At Newcastle Fertility Centre, currently the only UK clinic licensed to perform the procedure, researchers treated 22 couples whose eggs carried high levels of mitochondrial mutations. After fertilising those eggs with the fathers’ sperm, they then transferred the nuclear DNA into donor eggs that had healthy mitochondria and had had their own nuclei removed. Out of those treatments, seven women went on to have eight healthy babies; one more is currently pregnant, according to the Financial Times.
Dr Sir Doug Turnbull, a lead researcher from Newcastle, called the development “a landmark in genetic medicine,” noting that although mitochondrial DNA makes up less than 1% of a child’s total DNA, the impact is enormous. The children inherit their personality, appearance, and core traits from their parents; what they receive from the donor is just mitochondrial function: enough to power their cells, not their identity.
The NHS-supported trial reported a 36% success rate, comparable with standard IVF using genetic screening. All eight infants are developing normally, according to a Guardian report, showing no signs of mitochondrial disease. A few showed traces of mutated mitochondria, but at levels low enough not to cause health issues. Mary Herbert, one of the lead fertility experts, described the results as “way, way below the threshold” for concern.
What it means for the UK, and beyond
The UK has been at the forefront of this technology since changing its laws in 2015, allowing the Human Fertilisation and Embryology Authority to issue licences. Newcastle’s centre received its first licence in 2017, and it’s now running the world’s most advanced trial of this technique. Australia has also adopted the method and is expected to begin clinical trials next year, according to the Financial Times.
Families who lost children to mitochondrial disease are already calling this a game-changer. Liz Curtis, whose daughter Lily died from such a condition in 2006 and who now runs the Lily Foundation, called the news “super exciting.” The foundation, heavily involved in designing the study, sees mitochondrial donation as a long-sought hope for families who previously had no way to break the cycle of disease.
Experts stress this isn’t a mainstream fertility tool; it’s reserved for women where standard IVF plus embryo screening hasn’t been enough. As Dr Andy Greenfield from Oxford University explains, mitochondrial donation offers an option when all others have been exhausted. But for those families, it offers complete relief: this child will not suffer the disease that claimed their sibling or cousin.
Ethical questions and cautious optimism
The procedure does lead to germline modification, meaning any baby born via the technique will pass those donated mitochondria to their own children if they are female. That’s why in countries like the US, it remains banned, mainly out of concerns over heritable genetic changes. But in the UK, the process remains tightly regulated, with case-by-case approvals from HFEA and long-term follow-ups planned.
Leading voices stress that although mitochondrial DNA is a tiny fraction of our genome, it’s essential for cell energy. And while the term “three‑parent baby” makes headlines, experts say it’s misleading. As Robin Lovell-Badge from The Francis Crick Institute explains, the donor contributes no visible traits, only healthy cellular function.
Still, caution remains. Techniques like this are new, and the long-term health of these children must be monitored throughout their lives. For instance, the three babies who had low-level mitochondrial mutations will need regular checks to ensure those traces don’t grow. Newcastle researchers have designed protocols specifically for this purpose.