The first British baby made with the DNA of three people could be born next year after the UK’s fertility regulator gave the green light for clinics to seek licences for the procedure.

The Human Fertilisation and Embryology Authority (HFEA) announced on Thursday that it would accept applications from clinics wanting to offer the controversial therapy after it met to consider the latest scientific evidence for the safety of the procedure.



What is mitochondrial replacement therapy (MRT)? MRT is an experimental treatment that was made legal in Britain in 2015. It aims to prevent serious disorders from being passed to children, caused by mutations in mitochondria, tiny structures that provide energy inside cells. Children inherit all their mitochondria from their mothers. MRT uses healthy donor mitochondria to replace the faulty ones. The child therefore has the usual 46 chromosomes from its parents, plus additional DNA from the donor's mitochondria. To perform MRT doctors pluck the nucleus from the mother’s egg, place it in a healthy donor egg, then fertilise it. Another similar approach uses fertilised eggs.

The regulator’s decision was described as “a momentous and historic step” by Adam Balen, chairman of the British Fertility Society, and comes nearly two years after parliament voted to legalise the procedure.

Doctors in Newcastle are ready to offer the experimental treatment, called mitochondrial replacement therapy (MRT), to women whose faulty DNA puts them at risk of passing on devastating genetic diseases to their children. They intend to apply for a licence immediately and could begin treating patients as early as spring 2017.

Mary Herbert, professor of reproductive biology at the Newcastle Fertility Centre, said specialists at the clinic would apply for a licence to offer the treatment as soon as the HFEA made it possible for applications to be uploaded. “We’re delighted. This is a huge triumph for the research, for the regulatory process in the UK, and most importantly for all the families who are affected. We have everything ready to go,” she told the Guardian.

MRT was developed to help women with mutations in the DNA of their mitochondria to have healthy babies. Mitochondria are tiny battery-like structures that sit inside cells and provide energy for the tissues. Cells can have hundreds of mitochondria which are passed on solely from mother to child.



About one in 10,000 newborns are affected by mitochondrial disease. Many of these children die young, as the mutations cause the brain, heart, muscles and other energy-demanding tissues to fail.

“Today’s historic decision means that parents at very high risk of having a child with a life-threatening mitochondrial disease may soon have the chance of a healthy, genetically-related child. This is life-changing for those families,” said Sally Cheshire, chair of the HFEA. “We feel now is the right time to carefully introduce this new treatment in the limited circumstances recommended by the panel.”

MRT aims to prevent mitochondrial diseases from being passed on by replacing the defective mitochondria in a mother’s egg with healthy mitochondria from a donor. The resulting baby would inherit the full set of 46 chromosomes from its mother and father – it is this DNA that defines their appearance and other characteristics – but have the healthy donor’s mitochondria. The donor has no legal rights over the child.

The Newcastle team aims to apply for a licence in the next 24 hours that, if approved, would allow the clinic to offer the procedure. They must then submit a second licence application to perform the procedure on a particular patient who has decided to go ahead with the treatment. For each patient the doctors want to treat, a fresh licence is needed.

Women with faulty mitochondria already have a number of options if they want to have children. They can adopt, or have IVF with healthy donor eggs. If they wish to have genetically-related children, they can either take the risk of natural birth, or have IVF with a screening procedure called pre-implantation genetic diagnosis (PGD). This can help doctors to select embryos with the fewest mutations, but it cannot help when all of a woman’s embryos are affected.

While MRT could be a good alternative for some women, the treatment is not without its own risks. Studies suggest that small amounts of mutated DNA which remain in the treated embryo can sometimes bounce back and potentially scupper the therapy.

The procedure also raises ethical concerns. Because the genetic manipulation affects all of the cells in the embryo, it will affect the eggs or sperm the child. This means that any harmful side-effects of the treatment could not only appear in the treated child, but in their children too.

Doug Turnbull, director of the Wellcome Centre for Mitochondrial Research at Newcastle University, said his team aimed to treat 25 carefully-selected women a year to reduce their risk of passing on genetic diseases. The patients will all receive counselling and have other family planning options explained to them. Any children born from MRT will have full medical follow-up.

“We are delighted by today’s decision as it paves the way to offering mitochondrial donation as part of an NHS-funded package of care for families affected by mitochondrial DNA disease,” Turnbull said.

Frances Flinter, professor in clinical genetics at Guy’s and St Thomas’ NHS Foundation Trust, said: “This is wonderful news for families who have, in some cases, waited years or even generations for the chance of having a healthy baby. Mitochondrial disorders can be very serious, progressive conditions and some couples know that they will never be able to have a healthy child of their own without trying this new therapeutic approach.”

The first patients to have MRT in Britain could have babies before the end of 2017. They will not be the first three-person babies in the world. Earlier this year, a US team announced the birth of a baby boy after doctors performed the treatment at a clinic in Mexico. Tests on the child suggest that the treatment reduced the amount of mutated DNA he inherited to a level that should not cause disease. But doctors will not know for certain until he is much older. The same clinic is now planning to treat 20 more women in the first half of next year.

While the HFEA opted for a “cautious go-ahead”, some felt the regulator was not being cautious enough. Trevor Stammers, a bioethicist at the Catholic St Mary’s University in London, said a truly cautious approach would wait to see if the child born in Mexico developed normally. “Caution would surely warrant waiting to see if the boy stays free of disease,” he said.

But Robert Meadowcroft, CEO of Muscular Dystrophy UK, added: “Families have, understandably, had to wait through years of thorough ethical, safety and public reviews. We know of many women who have faced heartache and tragedy, and the sorrow of stillbirths, while trying to start their own family, and this decision gives them new hope and choice for the first time. We recognise this approach is not without some uncertainty, and, in any trial, success cannot be guaranteed. However, it is important that women are able to make informed choices by understanding the risks and the potential benefits.”

