The world’s first baby born using a new technique that incorporates DNA from three people is happy, healthy and making history.
The child, now a five-month-old boy, has the typical packages of DNA from his mom and dad, but he also has a tiny bit — 0.001 percent — of additional donor DNA acquired through a new in-vitro fertilization technique, called three-person IVF. He was born to Jordanian parents and treated by a US-based team in Mexico, New Scientist revealed in an exclusive report Tuesday.
Three-person IVF allows parents with rare genetic mutations to prevent passing them onto their offspring. In this case, the mother carries genes for Leigh syndrome, a fatal mitochondrial disease that affects the developing nervous system. The mutation claimed the lives of the couple’s first two children, so the they sought help from John Zhang and his team at the New Hope Fertility Center in New York City, New Scientist reports.
— New Scientist (@newscientist) September 27, 2016
Mitochondrial diseases are passed down the maternal line in families, and they are caused by mutations in a small number of genes in the mitochondria — the source of chemical energy needed for cells to sustain life. Roughly one in 6,500 children worldwide are born with mitochondrial disease, and it causes their organs to slowly fail. Currently, there are two primary methods to prevent this from happening.
One technique, called pronuclear transfer, involves fertilizing a maternal egg and a donor egg with the father’s sperm in a dish, and then removing the nuclei of both embryos after one day of development (when the embryo is still a single cell). The donor embryo then contains just a cell membrane and mitochondria. The parental nucleus is implanted into this new shell and goes on developing.
The second approach, called maternal spindle transfer, occurs before fertilization. This technique removes the nucleus and other innards of the maternal egg (leaving behind the diseased mitochondria) and implants them into a donor egg, which is then fertilized with the father’s sperm. The couple chose this method, because they are opposed to destroying embryos on religious grounds.
In 2015, the U.K. became the first country in the world to approve the pronuclear transfer technique, and it remains the only country to have legalized three-person IVF. The technique was deemed safe in a review published in the journal Nature, but there’s still a chance — a vastly reduced one — that disease-causing mitochondrial mutations can still be passed down.
Doctors will continue to monitor the child’s health, but his success story could make it easier for other legislative bodies to follow the U.K.’s lead.