8 healthy babies born in UK with DNA of 3 parents in IVF births

What Are Mitochondrial Diseases?

Mitochondria, often described as the “powerhouses” of cells, convert oxygen into energy that the body uses as fuel. When these structures are defective, they can cause severe conditions such as brain damage, seizures, muscle weakness, organ failure, and even death in infants. These diseases are passed down exclusively from mother to child, making maternal transmission particularly devastating—some parents have endured the loss of multiple children due to these disorders.

How the Technique Works

In the three-person IVF process, eggs from both the mother and a donor are fertilised in the lab with the father’s sperm. As the embryos develop, the nuclear DNA containing traits like eye colour and height is extracted from both. The DNA from the parents is then inserted into the donor embryo, which contains healthy mitochondria. The result is a baby who is genetically related to the parents but protected from mitochondrial disease.

Although over 99.9 per cent of the child’s DNA comes from the parents, a small portion about 0.1 per cent comes from the donor. This minor genetic change can be passed down through future generations if the child is female, raising complex ethical and scientific questions about genetic inheritance.

According to findings published in the New England Journal of Medicine, 22 families underwent the procedure, resulting in eight births – four boys, four girls (including a set of twins) and one ongoing pregnancy. All children were born free of mitochondrial disease. However, there were minor health concerns related to one child who experienced epilepsy that resolved without treatment, and another has an abnormal heart rhythm currently being managed.

A key concern was whether any diseased mitochondria might carry over during the transfer. In five cases, none were detected; in the remaining three, between 5 per cent and 20 per cent of faulty mitochondria were present in blood and urine samples which is still below the 80 per cent threshold typically associated with disease.

The UK not only discovered this science but also became the first country to legalise it, following a historic vote in Parliament in 2015. While the technique sparked ethical debate, particularly because mitochondria contain their own DNA, scientists and lawmakers agreed that its potential to prevent suffering outweighed concerns about “designer babies.”

Each year, around 20 to 30 families in the UK are expected to opt for this technique. With continued research and careful regulation, three-person IVF could offer a lifeline to families at risk of passing on devastating genetic diseases.