This new controversial technique enables a parent with a genetic mutation or illness to have a healthy baby free from the same genetic mutation or illness. In this particular case, the baby's mother is a carrier of Leigh syndrome, a fatal disorder that affects the developing nervous system. Leigh syndrome was the cause of death of the mother's two previous children.
On hearing about the chance to have a healthy child, free from the genetic mutation, the mother and her partner sought out the help of John Zhang and his team at the New Hope Fertility Center in New York City.
To prevent the mother passing on the genetic mutation through her mitochondrial DNA (which we inherit from our mothers) to the child, the scientists used mitochondria from an egg belonging to another woman – an anonymous donor. The baby therefore has the genetic make-up of three separate adults.
The birth of this healthy baby boy, who is currently showing no signs of inheriting his mother's genetic mutation, is seen as a beacon of hope to other parents wishing to have children without passing on a gene which may cause them long-term health issues or even premature death.