Medical technology, particularly genetic technology, has come a long way in my lifetime. I remember in high school doing a paper on the then young Human Genome Project, and now a quarter-century after that milestone was launched we have the first instance of a child born using a new technique allowing two parents with a third providing mitochondrial DNA.
The controversial technique, which allows parents with rare genetic mutations to have healthy babies, has only been legally approved in the UK. But the birth of the child, whose Jordanian parents were treated by a US-based team in Mexico, should fast-forward progress around the world, say embryologists.
The boy’s mother carries genes for Leigh syndrome, a fatal disorder that affects the developing nervous system. Genes for the disease reside in DNA in the mitochondria, which provide energy for our cells and carry just 37 genes that are passed down to us from our mothers. This is separate from the majority of our DNA, which is housed in each cell’s nucleus.
Around a quarter of her mitochondria have the disease-causing mutation. While she is healthy, Leigh syndrome was responsible for the deaths of her first two children. The couple sought out the help of John Zhang and his team at the New Hope Fertility Center in New York City.
Zhang has been working on a way to avoid mitochondrial disease using a so-called “three-parent” technique. In theory, there are a few ways of doing this. The method approved in the UK is called pronuclear transfer and involves fertilising both the mother’s egg and a donor egg with the father’s sperm. Before the fertilised eggs start dividing into early-stage embryos, each nucleus is removed. The nucleus from the donor’s fertilised egg is discarded and replaced by that from the mother’s fertilised egg.
But this technique wasn’t appropriate for the couple – as Muslims, they were opposed to the destruction of two embryos. So Zhang took a different approach, called spindle nuclear transfer. He removed the nucleus from one of the mother’s eggs and inserted it into a donor egg that had had its own nucleus removed. The resulting egg – with nuclear DNA from the mother and mitochondrial DNA from a donor – was then fertilised with the father’s sperm.
Zhang’s team used this approach to create five embryos, only one of which developed normally. This embryo was implanted in the mother and the child was born nine months later. “It’s exciting news,” says Bert Smeets at Maastricht University in the Netherlands. The team will describe the findings at the American Society for Reproductive Medicine’s Scientific Congress in Salt Lake City in October.
Neither method has been approved in the US, so Zhang went to Mexico instead, where he says “there are no rules”. He is adamant that he made the right choice. “To save lives is the ethical thing to do,” he says.
The team seems to have taken an ethical approach with their technique, says Sian Harding, who reviewed the ethics of the UK procedure. The team avoided destroying embryos, and used a male embryo, so that the resulting child wouldn’t pass on any inherited mitochondrial DNA. “It’s as good as or better than what we’ll do in the UK,” says Harding.
It's that last couple paragraphs that should remind us all that science always tends to be ahead of legislation. Ethical questions aside, we need a group of educated lawmakers in a representative democracy system in order to make determinations on subjects such as this, and our current Congress isn't anywhere close to meeting that criteria, not when one party, which currently controls Capitol Hill, is happy to flaunt how anti-science it is at every turn.
We need better lawmakers. Of course, that goes without saying.