Moms Can Pass On Genetic Diseases, Even After Her Egg Is Paired With A Donor Egg

Back in April, a seemingly healthy baby boy born in Mexico dominated international headlines as he was conceived through a controversial method, which uses a handful of selected genes from three parents. The technique is a preventative measure to eliminate the risk of passing devastating mitochondrial diseases on to fetuses — disorders that can make it impossible for the cells responsible for producing energy to function properly. Now, new research suggests that the reproductive technology may have some kinks to work out after all. A new study has found that moms can still pass on genetic diseases, even after her egg has been paired with a donor egg and her mitochondria has been wiped.

The findings, discovered by a group of scientists from Oregon Health & Science University in Portland, were published on Wednesday in Nature — an international weekly science journal. The researchers found concerning evidence that shows that the promising "three-parent baby" technique is not always effective and, as previously mentioned, can still pass on defective mitochondria to a child, which can lead to serious illnesses caused by the genetic malfunction.

Faulty mitochondria can have a devastating impact on someone’s life because those cells are responsible for generating "90 percent of the energy needed to sustain life and support organ function," according to the United Mitochondrial Disease Foundation. So when these cells don’t do their jobs, severe weakness can occur as organs start to fail. These disorders can sometimes even lead to death.

The group of genetic scientists came to the conclusion after they performed the procedure by combining the eggs of four women who carried mitochondrial mutations that had caused diseases in their families along with eggs donated by healthy women. As one doctor described the process to Scientific American, it's like "taking the 'yellow part' of a mother’s egg and inserting it into the 'white' of a donor’s egg."

The initial results were promising, but they ultimately found that three of the 15 embryos included in the study eventually regained the mother’s original set of mitochondria with the potential to cause disease.

"It’s not perfect. There’s this chance of something going wrong," developmental biologist Robin Lovell-Badge said, according to the study.

But, Shoukhrat Mitalipov, the developmental biologist who led the research, told Scientific American that while the risk that genetic disorders may develop again are present, the effects are likely to be rare. Instead, Mitalipov and reproductive endocrinologist Paula Amato say that mitochondrial replacement therapy could be tested in a clinical trial and could prove to be the answer to the newly discovered issue.

Amato told Scientific American that "because these diseases are so debilitating and often fatal and there are no cures, we think it’s still worth trying to move this research forward to prevent those diseases if we can."

The reproductive procedure was originally intended to prevent Leigh syndrome — a severe neurological condition that affects at least one in 40,000 newborns, as a result of defective mitochondria — but many scientists now believe that more research needs to be done to completely prevent the baby from receiving the potentially mutated DNA. In the meantime, the process could possibly be used a method to treat infertility as well.

Controversy aside, the latest research can be viewed as bit of a concern for the science behind the procedure. But, it's reassuring to know that researchers are working diligently to address the problem.