The first baby in the UK created with DNA from three people has been born, after doctors performed a groundbreaking IVF procedure that aims to prevent children from inheriting incurable diseases.
The Human Fertilisation and Embryology Authority (HFEA) said “less than five” babies have been born using the technique. No further have been released, to protect their identity.
Although it is early days, it is expected that there will be many more such births in the UK – and around the world – in the coming years, assuming the process is found to be safe and effective enough to continue.
Why would a couple use this technique?
The technique, known as mitochondrial donation treatment (MDT) is aimed at stopping a mother from passing on defective genes in mitochondria to her child.
Mitochondria act as the batteries of the cells, giving energy, and if they do not work properly it prevents normal development.
What does MDT involve?
MDT uses tissue from the eggs of healthy female donors to create IVF embryos that are free from harmful mutations that their mothers carry, and would be likely to pass on to their children.
First, sperm is taken from the father and used to fertilise eggs from the affected mother and from a healthy female donor.
Next, the “nuclear” genetic material from the donor’s egg is removed, and replaced with material from the couple’s fertilised egg.
The resulting egg has a full set of chromosomes from both parents – but also carries the donor’s healthy mitochondria, instead of the mother’s faulty ones.
So an embryo created using MDT combine sperm and egg from the biological parents with tiny battery-like structures (mitochondria) from the donor’s egg.
This is then implanted in the womb.
How much of the baby’s DNA comes from the third parent?
Almost all of the DNA the child will have comes from the mother and father, defining key characteristics such as personality and eye colour.
But they will also have a tiny amount of mitochondrial DNA provided by the “third parent”.
Mitochondria hold only about 0.1 per cent of a person’s DNA – representing 37 genes – which is always inherited from the mother. So although the child technically has three parents – and that 0.1 per cent of genetic material plays a vital role in the child’s health – it is essentially the offspring of two parents.
The DNA from the second woman only affects the mitochondria, and does not affect other key traits in the child.
How serious are mitochondrial diseases?
About one in 6,000 babies are born with mitochondrial diseases.
These cause long-term, genetic and often inherited disorders that occur when mitochondria fail to carry out their function of producing energy for cells in the body. These illnesses can be very serious and often fatal.
In children, symptoms can include poor growth, poor muscle tone, weakness, spasms and a slowdown in progress or a slow deterioration.
Some families have lost several children to inherited mitochondrial diseases and MDT is seen as their only chance of having a healthy child.
Who is eligible for MDT treatment?
Anyone at very high risk of passing serious mitochondrial disease onto their children could be eligible for treatment.
The HFEA says people can speak to their GP or contact Newcastle Fertility Centre at Life – the only national centre which has a licence to carry out research and treat patients using the technique.
All mitochondrial donation treatment needs to be approved by the HFEA to ensure it is done in a legal and ethical way.
Scientists believe the technique could offer hope to about 150 women a year, with dozens already expressing an interest.
Does the mitochondrial donor have any rights over the child?
No. A woman who donates their eggs and/or embryos for use in mitochondrial donation treatment will not be the genetic parent of the child that is then born. This is because the mitochondria provides less than 1 per cent of the child’s genetics.
The donor therefore does not have any legal rights or responsibilities over the child and the donor remains anonymous.
However, from the age of 16, the child can access some information about the mitochondrial donor, though this will not identify the donor.
This information can include something about their personal and family medical history, a personal description if provided by the donor, plus any additional information which they have agreed to share with the child.
Is the UK a leader in MDT?
The process was pioneered at the Newcastle Fertility Centre and Britain became the first country in the world to formally allow mitochondrial replacement therapy (MRT) when the HFEA gave a cautious green light to the procedure in 2017.
However, the first three-parent baby was born in 2016 in Mexico, where there is not a strong regulatory framework.
Approval in the UK is given on a case-by-case basis by HFEA, which is thought to have given the green light for at least 30 cases.
Doctors at the Newcastle clinic have not released details of births from its MDT programme, amid concerns that specific information could compromise patient confidentiality. However, in response to a freedom of information request by the Guardian, the HFEA confirmed that a small number of babies have now been born in the UK after MDT.
How effective is MDT and are there risks associated with it?
The procedure is not without risks and it is not known whether the babies born in the UK using it are healthy.
As such, scientists, regulators and doctors will be watching the outcomes of these births very closely as and when the data becomes available.
Previous research has found that in some cases, the tiny number of abnormal mitochondria that are inevitably carried over from the mother’s egg to the donor egg can multiply when the baby is in the womb. So-called reversion or reversal could lead to a disease in the child.
It is not clear why reversal is seen in the cells of some children born following MRT procedures, but not in others. Experiments on monkeys and mice have suggested that such babies would probably be healthy but that does not automatically mean it will be in humans.
What happens next?
Experts will proceed cautiously and scrutinise the evidence. “These are still early days for mitochondrial donation treatment and the HFEA continues to review clinical and scientific developments,” said Peter Thompson, chief executive of the HFEA.
Sarah Norcross, director of the Progress Education Trust, said UK laws relating to the treatment were “passed only after many years of careful research, assessment and deliberation”.
She added: “Even then, it was decided that use of this technology would be permitted by the regulator only on a case-by-case basis. This measured approach was and is appropriate, given the relative novelty of this technology.
“News that a small number of babies with donated mitochondria have now been born in the UK is the next step in what will probably remain a slow and cautious process of assessing and refining mitochondrial donation.”
Professor Robin Lovell-Badge, of the Francis Crick Institute, said: “While knowing that babies have been born in the UK following the use of mitochondrial replacement techniques is newsworthy, especially as this is being done in an appropriately regulated environment, scientists, clinicians and patients will want to see the details.
“I am sure that these will be made available, probably in a peer-reviewed scientific publication and hopefully in the near future. The Newcastle team involved in carrying out the procedures are cautious and will have wanted to include at least some follow-up data on the babies, while also protecting the privacy of the families. This is a challenge in itself.”
“It will be interesting to know how well the MRT technique worked at a practical level, whether the babies are free of mitochondrial disease, and whether there is any risk of them developing problems later in life or, if female, if their offspring are at risk of having the disease.
“Such problems might arise if there is ‘reversion’, where the initially small amounts of the mother’s mitochondrial DNA, with the disease-causing variant gene, that are carried over with her nuclear DNA, are amplified.”
