The world's first child created using a controversial 'three-parent' baby technique has been born in Mexico, it has been announced.
Limited details about the birth were revealed ahead of the American Society of Reproductive Medicine's scientific congress in Salt Lake City next month, where it will be discussed more fully.
According to critics, the procedure is tantamount to genetic modification of humans or even "playing God". But supporters say it allows women with a particular type of genetic disease to have healthy children who are related to them.
A report in the New Scientist magazine said the baby was now five months told. His parents are Jordanians and the work was carried out by a team of experts from the US.
The child's mother has Leigh syndrome, a fatal disorder that affects the developing nervous system and would have been passed on in her mitochondrial DNA.
Although she is healthy, two of her children have died as a result of inheriting the disease, a girl who lived until she was six, and an eight-month-old baby.
There are different ways of creating a so-called three-parent baby.
The technique used by Dr John Zhang, of the New Hope Fertility Clinic in New York, and his team involving taking the nucleus from one of the mother's eggs – containing her DNA – and implanting it into a donor egg that had its nucleus removed but retained the donor's healthy mitochondrial DNA.
Unlike ordinary DNA, which has the genetic information that helps make us who we are, mitochondrial DNA provides power for the cell and has been compared to a battery. Many scientists in the field insist the term ‘three-parent baby’ is inaccurate for this reason as the significant DNA is still from two people.
Dr Zhang told the New Scientist that, as the technique has not been approved in the US, the team went to Mexico where "there are no rules".
“To save lives is the ethical thing to do,” he added.
In 2003, Dr Zhang and his team revealed they had used a different technique to create three-parent babies, sparking international outrage.
The UK parliament voted to allow the creation of 'three-parent babies' in principle but regulators must still decide whether the specific technique is safe before such a birth could happen in Britain.
Other scientists working in the field welcomed the news.
Professor Bert Smeets, director of the Genome Centre at Maastricht University, said: “At last, the first child of a mother with a mtDNA mutation is born after mitochondrial donation.
"The safety of the method had already been quite convincingly demonstrated by the Newcastle group in the UK and introduction into the clinic would only be a matter of time – obviously, dependent on national regulation or the absence of it.
“A US-based research group apparently escaped the more rigid regulatory framework in the US to perform this treatment in Mexico. That is a concern, especially as the framework not only safeguards the introduction into the clinic, but also the follow-up of the children borne after this treatment.
"Hopefully, now the first child is born and the heat is off, it takes away the pressure to involve patients in unsecured treatments, when good alternatives are available."