CHILDREN with three parents might sound like monstrous chimeras, but they are among us already. In the late 1990s, an American team created the first genetically engineered humans by adding part of the egg of one woman to the egg of another, to treat infertility. When the US Food and Drug Administration got wind of the technique it was promptly banned, though have been used in other countries.
Now a research team in the UK is experimenting with creating three-parent embryos. This time, the goal is to prevent children inheriting a rare group of serious diseases caused by faulty mitochondria, the powerhouses in our cells. Mitochondrial diseases affect at least 1 in 8000 people, probably more, and there are no treatments.
Mitochondria are always inherited from the mother, so for women in whom they are faulty, replacing the mitochondria in their eggs with healthy ones from a donor would help ensure their children are healthy. What makes the idea controversial is that mitochondria contain DNA of their own, meaning babies created this way will have genes from a “second mother”.
Supporters of this approach point out that mitochondria contain a mere 37 of the 20,000 or so human genes. Changing them is akin to changing a battery, they argue. Yet it is becoming increasingly clear that the : different variants can affect our energy, athleticism, health, ageing, fertility, perhaps even our intelligence, all of which help make us who we are as individuals.
The prospect of trying to prevent mitochondrial diseases by creating babies with two mothers raises a host…
