Eight babies have been born via a new IVF technique called mitochondrial donation. What is it?

Researchers in the United Kingdom have announced the successful birth of eight babies after a clinical trial of an IVF technique known as mitochondrial donation.

The pioneering technique — which some in the media have dubbed "three-person IVF" — has been developed to prevent the sometimes fatal and incurable mitochondrial (mito) disease.

Researchers hope clinical trials using this technique could be held in Australia within years.

Here's how it works.

What is mitochondrial disease?

Mitochondria are parts of a cell that break down food and turn it into energy.

They're found in almost every cell of the human body.

When they don't work properly, they can drain the body of energy, which can result in a rare condition called mitochondrial disease.

It can cause problems like weak muscles, diabetes, deafness, vision loss, and heart disease, but at its worst, children can die before birth or soon after from widespread organ failure.

In Australia, about 60 babies born each year will develop a serious or fatal case of mitochondrial disease, and only mothers can pass it on to their children.

As there is no cure, scientists have focused on IVF technologies to reduce the likelihood of mothers passing this genome onto their children.

This is where "pronuclear transfer", or mitochondrial donation, comes in.

How does it work?

It involves a technique where a woman's disease-causing mitochondria are replaced with those from another woman's egg.

An egg with disease-causing mitochondrial DNA is fertilised with sperm via IVF.

The resulting "pronucleus" — which contains the couple's genetic material — is removed from the egg and then transferred to the donor egg.

This donor egg has healthy mitochondria and has already had its genetic material removed.

The resulting embryo inherits the parent's DNA, but the mitochondrial DNA comes from the donor egg.

This process greatly reduces the baby's chance of developing mitochondrial disease.

What does the study show?

A research team at Newcastle University in the UK tested this method with 25 women who were at a high risk of passing on disease-causing mitochondrial DNA.

It found undetectable or low levels of the DNA in eight babies, while another pregnancy is ongoing.

Professor John Carroll, director of Monash's Biomedicine Discovery Institute and head of mitoHOPE — which aims to pilot this technology in Australia — said he was excited about the outcome, which had been decades in the making.

"For families that would have very likely had children with high levels of mitochondrial genetic disease, they've been able to prevent that," he said.

Are there safety or ethical concerns?

Professor Carroll said it was the first scientific study of this technique and therefore was "early days".

"We have to proceed with care, with caution, step by step to make sure it's as safe as it possibly can be," he said.

"We really have to monitor those babies and children as they grow up and make sure that none of the disease-causing mitochondria come back.

"That's a really important part of this whole process."

But he said the research was "remarkable" so far.

"[We have] eight babies born to families who would've normally had very ill children," Professor Carroll said.

Swinburne University bioethicist Evie Kendal also said this technology was different to the process which could lead to gene-edited or "designer babies".

"Mitochondrial donation is only really targeting those specific mitochondrial diseases that are impacted by mutations in that mitochondrial DNA," she said.

"So it's not something that we could manipulate to change the traits of offspring, and most genetic conditions are of course related to mutations in the nuclear DNA."

Is it 'three-person IVF'?

Some have dubbed the technique "three-person" or "three-parent" IVF, because it uses two eggs and sperm to make a baby.

But Professor Carroll said this wasn't technically correct. Instead, he said it should be thought about as a couple and an egg donor.

This is because the genome — which determines the physical attributes of a person — comes from the parents, while the donor egg carries the mitochondrial DNA.

“All of the genes that make us who we are … they are all from the parents,” he said.

When will it happen in Australia?

In March 2022, the federal government passed legislation, known as Maeve's Law, to allow the use of mitochondrial donation to prevent the transmission of severe disease under strict regulatory conditions.

While a clinical trial using this technology hasn't been approved yet in Australia, it's not far off.

A program called mitoHOPE has been set up to pilot mitochondrial donation in Australia. It's a collaboration between Monash IVF, Monash University and the Murdoch Children's Research Institute, which received $15 million in funding from the federal government in 2023.

Professor Carroll, who is the president of the program, said they were in the process of applying for the licence required to start a clinical trial.

He also said one of the lead researchers involved in the UK research, Professor Mary Herbert, was now working at Monash University with mitoHOPE.

"For the first time, we have now an evidence base and experience of mitochondrial donation in a clinical setting," he said.

"That really gives the ethics committees who are looking at the work, the regulators who are looking at the work, some real reassurance that this technique works."

Professor Carroll said he hoped a clinical trial would be underway in the second half of next year, and encouraged willing participants to get in contact. 

Monash IVF, which has had two high-profile incidents of incorrect embryo transfers in recent months, said the mitoHOPE Program was subject to "strict regulatory oversight".

"[It] is being conducted in full compliance with Australian legislation and the required licensing framework," a spokesperson said.