We know of one case where it didn’t seem to work. The baby was born from an embryo in which PGT detected about 12% of the mother’s “bad” mtDNA. But by the time the baby was born, the proportion had soared to about 50%. This child had a variety of symptoms, including abnormal brain development, behavioral problems, and signs that he had suffered a brain hemorrhage.
Only a small number of children have been born after using PGT to screen for mitochondrial disease, so again, it is difficult to draw conclusions. A French center that pioneered the treatment and has been offering it since 2006 recently reported that it had only 29 babies born this way, Heindrick says. His own center has only used it to deliver four or five babies in the past 10 years. And, as with MRI reversal, there’s a chance that babies who don’t have the disease at birth can develop the disease as they grow older.
“It’s alarming,” Heindrick says. “We also need to monitor babies born after PGT, because it could be that this reversion is happening there as well.”
A dangerous option?
What does this mean for the MRT in the meantime? While the Newcastle team plans to continue the trial, others warn that, at least for now, we should hold off on using MRI to treat mitochondrial disease and instead study it in people who don’t have the disease, such as infertility.
Mazur himself refuses MRI for mitochondrial disease. And Heindrik says the risk is too high for him — with a 20% risk of reversion, he says the ethics committee at his institution won’t allow him to use MRI to treat mitochondrial disease.
Mertes says she’s never been a fan of MRI tests. Scientists knew in advance that the tests would never be without risk and that they involved the potential waste of perfectly good donor eggs and embryos. “At the end of the day, you’re offering patients an option that’s more dangerous than their alternative,” she says.
Experimental treatments like MRIs also help reinforce the idea that it’s important for parents to have a genetic connection to their children, Mertes says. “Wouldn’t it be wiser to ask whether that genetic connection is so important if the price you have to pay is risking your child’s health?” – she asks. Parents can avoid all the risks associated with MRI if, for example, they use a donor egg instead of their own egg or adopt a child.
In the meantime, clinics that offer MRIs should update the information they provide “so people know this is a very real risk they’re taking,” Mertes says. Both she and Prior believe the treatment should be limited to those who “need it” or at least strongly believe they want a genetic link with their children.
Mitalipov is confident that scientists like him will eventually come up with a solution to mitochondrial reversion. “We just need to figure out why it’s happening,” he says. “No clue yet… but give us time.”