Multiple babies were born in the U.K. using a "groundbreaking IVF procedure" that combined the DNA of three people, The Guardian reports.
The procedure, called mitochondrial donation treatment (MDT), can be used to prevent a number of diseases. In MDT, scientists use "tissue from the eggs of healthy female donors to create IVF embryos that are free from harmful mutations their mothers carry and are likely to pass on to their children." The new embryos contain less than one percent of the donor's DNA, per The Associated Press. The first successful birth using the treatment occurred back in 2016.
"Mitochondrial donation treatment offers families with severe inherited mitochondrial illness the possibility of a healthy child," The Human Fertilization and Embryology Authority, the U.K.'s fertility regulator, said in a statement. Mitochondrial disorders can impact the brain, muscles, liver, and heart because the body isn't being properly fueled, and can lead to death just a few hours after birth. Even with the treatment, however, there is a risk of "reversion," BBC notes, which is when "any defective mitochondria that are carried over could gain in number and still result in disease."
"It will be interesting to know how well the (mitochondrial donation) technique worked at a practical level, whether the babies are free of mitochondrial disease and whether there is any risk of them developing problems later in life," commented Robin Lovell-Badge, a stem cell expert at the Francis Crick Institute.
Despite its success, some are concerned about the technique because of the potential for reversion. "These mitochondrial diseases have devastating consequences," said Björn Heindryckx at Ghent University in Belgium. "We should not continue with this." Others fear the procedure starts down a "slippery slope" whereby parents could use it "to have taller, stronger, smarter, or better-looking children," per AP.
"So far, the clinical experience with [MDT] has been encouraging, but the number of reported cases is far too small to draw any definitive conclusions about the safety or efficacy," Dagan Wells, a professor of reproductive genetics at the University of Oxford, told The Guardian.