The British government has said it will pursue a radical fertility technique that uses DNA from three parents to create an embryo.
The IVF-based technique is designed to avoid serious mitochondrial diseases inherited on the maternal side, such as muscular dystrophy.
Mitochondria are the structures within cells that convert energy from food into a form that the body can use.
The technique would replace some of the unhealthy DNA with healthy DNA from the so-called "third parent".
"It's only right that we look to introduce this life-saving treatment as soon as we can," said Sally Davies, the chief medical officer for England.
Politicians are due to debate the regulations in parliament next year, setting the stage for Britain to become the first country to offer the treatment.
One in 200 children is born each year with a form of disease in their mitochondrial DNA.
Scientists are developing a technique to remove some of the mitochondrial DNA of the mother and replace it with DNA from the "third parent" to create a healthy embryo.
All of a human's visible characteristics are encoded in DNA found in the cell nucleus. This means that any child born using the technique under consideration will only bear the features of two parents.
The technique is currently lawful in a laboratory but the embryos cannot be used in treatment.