Zhang worked with a way to avoid the disease by using "three-parents".
But babies with three parents have been born before, though the process was slightly different. The healthy five-month-old boy has DNA from three people.
A "revolutionary" new DNA splicing technique has resulted in the birth of the first child containing the DNA of three parents in a procedure to control the passing on of harmful genetic conditions. The parents' genetic information is inserted into the donor's embryo, which has had everything but the mitochondria cleared out. "They produce energy for the organism, possess their own genetic material - mitochondrial DNA (mtDNA) - and are transmitted exclusively by the mother. The translation of mitochondrial donation to a clinical procedure is not a race but a goal to be achieved with caution to ensure both safety and reproducibility", she said.
For now, there is no country where the method used to conceive the baby boy is explicitly legal. Some worry it could also lead to intelligent design of babies, meaning we could maybe in the future pick which traits we want in our children and dismiss others. Professor Doug Turnbull, from the University of Newcastle, said: "There have been extensive discussions in the United Kingdom to ensure that families with mitochondrial disease get the best possible advice about their reproductive options and that any new IVF-based technique is appropriately regulated and funded". However, rigorous checks are still needed.
"With radical new treatments like this there are always challenging ethical issues, however any concerns need to be balanced against the ramifications of not implementing such a technology when families are in need of it". The doctors chose to conduct it in Mexico.
Dr. John Zhang and his colleagues took all the vital DNA from the mother's egg.
In this case, the procedure was done because the eggs of the mother contained faulty mitochondria. The rest of his genetic code is from her parents.
There were five embryos created by the United States team in the similar way and only one of them developed properly. However, only one of them developed normally. Another professor said that it is regrettable that it is taking place in countries that are distant to serious ethical and technical aspects of scientific procedures which mean it is going to be hard to use the conclusions of this study in an organised data collection. What would the child feel of having DNA from three people? But the omnibus fiscal 2016 budget bill passed by Congress in 2015 prohibited the use of government funds for experiments that genetically alter human embryos.
Critics say the work is irresponsible. The doctors should not have ignored the cautious approach of USA regulators.
Some scientists said the move was irresponsible because not enough research had been done to know whether it was safe. "To save lives is the ethical thing to do", Zhang said in a statement. Others say the procedure has not been tested long enough and argue that changing an embryo in this way could pave the way for "designer babies".
It was not approved in the USA to try the three DNA technique.