The world’s first baby has been born using a controversial new “three-parent” fertility technique emplyed by scientists to include DNA from three people in an embryo, said a report in New Scientist magazine on Tuesday.
The baby boy, Abrahim Hassan, was born five months ago in Mexico to Jordanian parents, and is healthy and doing well. He has the usual DNA from his mother and father, in addition to a tiny bit of genetic code from a healthy female donor.
The boy's mother carries genes for a disorder known as Leigh syndrome, a fatal neurological disorder that causes the progressive loss of movement and deterioration of mental functions. It affects the DNA in mitochondria and passes down from mother to child.
Children with the condition usually die within two or three years due to respiratory failure.
Hassan’s parents had already experienced four miscarriages. The mother had passed on the genes for the disorder to her two previous children who both died of the disease.
— New Scientist (@newscientist) 27 September 2016
The couple approached John Zhang, a doctor from the New Hope Fertility Center in New York City, to have a baby that would be genetically related to them but would not carry the inherited disease.
The United States has not approved any three-parent method for fertility purposes, so Zhang went to Mexico where he was quoted by New Scientist as saying “there are no rules.”
Another method that has been approved in the United Kingdom, called pronuclear transfer, was deemed unacceptable to the couple because it would involve the destruction of two embryos, said the report.
Since the mother carried the genes for the disease in her mitochondria, or DNA that is passed down from the maternal side, Zhang used her nuclear DNA and combined it with mitochondria from an egg donor, in a technique known as spindle nuclear transfer.
“He removed the nucleus from one of the mother's eggs and inserted it into a donor egg that had had its own nucleus removed,” said the report.
“The resulting egg — with nuclear DNA from the mother and mitochondrial DNA from a donor — was then fertilised with the father's sperm.”
One of the created embryos was implanted into the mother and the baby was born nine months later.
Experts say the development opens a new era in medicine and many couple with rare genetic conditions may approach the technique to have a baby.
However, some warn that the new technique is controversial as it requires mitochondrial donation which has only been legally approved in the United Kingdom.
Presentation next month
Zhang and his team are expected to describe their method at the American Society for Reproductive Medicine meeting in Salt Lake City, Utah, next month.
Attempts began in the 1990s to create a baby by injecting mitochondrial DNA from a donor into the mother's egg, and adding sperm from her partner.
“Some of the babies went on to develop genetic disorders, and the technique was banned,” said the New Scientist report.
“The problem may have arisen from the babies having mitochondria from two sources.”
An outside expert, David Clancy, a lecturer at Lancaster University, recalled that experiments in monkeys have shown that maternal mitochondrial DNA can expand from low levels to significantly higher levels, “which would allow disease to again be transmitted, so we must expect the possibility in humans.”
For now, Zhang and his team said the boy's mitochondria has been tested and “they found that less than 1 percent carry the mutation,” said the report.
“Hopefully, this is too low to cause any problems; generally it is thought to take around 18 percent of mitochondria to be affected before problems start.”
In addition, his being a boy ensures that he could not pass down any inherited mitochondrial DNA.
“While we should remain vigilant about this technique as new information and research accumulates, let us hope this child grows up and has a long healthy life,” said Clancy.