A healthy, five-month-old baby has been revealed to be the first to be born of a new procedure that uses DNA from three individuals. The technique was used so as to remove a mitochondrial genetic disorder, which is carried by the boy’s mother and had claimed the lives of her first two children. Scientists hope that with the apparent success of their technique, the method will be more speedily approved around the world to allow parents with rare genetic mutations to have healthy children.
The procedure was conducted by a team of doctors led by Dr. John Zhang, from the New Hope Fertility Center in New York, in Mexico, where there are no current legal restrictions (the process is outlawed in the U.S.).
As New Scientist reports, the mother, who is from Jordan, carries genes for Leigh Syndrome, a rare disorder that attacks the developing nervous system. The genes that carry Leigh syndrome reside in DNA in the mitochondria, which is passed down from our mothers and provides just 37 genes to a developing embryo. The rest of our DNA comes from the nucleus.
Zhang’s technique–which has been deemed “revolutionary”–saw the nucleus taken from one of the mother’s eggs and implanted into a donor egg from which the nucleus had been removed, that egg was then fertilized with the father’s sperm.
The result is an egg that features nuclear DNA from the mother, and mitochondrial DNA from a healthy female donor. Of the five embryos that Zhang created with this method, one developed normally and was implanted into the mother, who gave birth to a baby boy on April 6 of this year.
Tests of the boy’s mitochondria show that less than one percent carry the mutation for Leigh Syndrome, which Zhang believes means the child will be completely healthy–it is only when 18 percent or more of the genes carry the mutation that health problems begin.
While there is significant excitement among experts at the apparent success of the technique, there will be a close eye kept on the development of the child. As Bert Smeets at Maastricht University in the Netherlands explained to New Scientist, there is a concern that the faulty mitochondria could be better at replicating, and that the levels of the mutated gene might increase over time:
We need to wait for more births, and to carefully judge them.