The modern era of the so-called "three-parent baby" has officially kicked off and it will begin in the UK.
According to the BBC, the country's Human Fertilization and Embryology Authority (HFEA) has granted permission for doctors at the Newcastle Fertility Centre to artificially implant two women with an embryo containing the DNA of three people.
The procedure is intended to prevent the women from passing a rare, debilitating genetic condition known as MERRF (myoclonic epilepsy with ragged red fibres) syndrome down to their children. People born with MERRF suffer a wide variety of chronic symptoms, including seizures, impaired muscles, and eventually dementia.
There are two current techniques that can be used to create a three-parent baby, but the net result is the same: A child born with the nuclear DNA of their intended parents, and the swapped-in mitochondrial DNA of a donor woman.
Mitochondria are an essential part of nearly every kind of cell found in the body, acting as the cell's source of energy. But only a tiny slice of our DNA determines how our mitochondria functions — a whooping 37 genes out of more than 20,000.
And none of these genes influence things like our appearance, risk of some cancers, or propensity for Cheetos. But because we obtain the genes for making mitochondria exclusively from our mother, women whose mitochondria have damaging mutations are at high risk at passing on those same flaws to their children, including those responsible for MERRF syndrome.
Three-parent babies actually aren't new. Similar procedures were performed throughout the 90s in various countries, including the U.S. But concerns emerged that the techniques used then were too risky, and may have resulted in children who were either born with the same mutations their mothers had or who developed other complications.
Within a few years, the FDA banned these procedures from being performed in the States, while other countries informally followed suit.
The new generation of three-parent techniques are thought to be much safer. But there are still worries that we might be moving too fast. Last year, the FDA warned John Zhang, a New York fertility doctor, to steer clear of the US. if he wanted to perform his version of the technique, since there is still a formal ban on implanting women with genetically modified human embryos.
Zhang is credited as the first doctor to successfully perform the modern-day procedure, but ethicists have balked at the shady workarounds he used to pull it off. According to the FDA, Zhang's initial application to have the procedure put through clinical trials was denied, and he promised to avoid performing it stateside until he could gain approval.
But he's also continued to advertise it as a way to not only prevent mitochondrial birth defects, but age-related infertility. Meanwhile, other teams from China and the Ukraine have also reported using three-person techniques in the wake of Zhang's success.
The UK has long been preparing for the arrival of three-parent babies. In 2015, parliament passed regulations that would eventually allow the use of these techniques, pending a lengthy review process by the HFEA. Last year, the agency finally granted its first licence to perform the procedure to the Newcastle Fertility Centre. For the time being, each potential case will be reviewed by the HFEA before its approval.