Is the moral debate over? Ten years ago, experts were bitterly divided over the ethics of allowing three-parent babies. But recent developments suggest that the treatment might be a resounding success.
Three-parent babies born disease-free
Chance of a normal life: The mitochondria are known as "the powerhouse of the cell" — but when somebody has mitochondrial disease, this power is missing. Glossary
DNA - Deoxyribonucleic acid is the material in an organism that carries genetic information.
Mutations - Changes to the structure of genes.
IVF - In vitro fertilisation is a technique used to help people with fertility issues have a baby.
Uterus - The organ in which a foetus (unborn baby) develops. Also known as the womb.
Embryo - A fertilised egg that is developing into a foetus.
Foetus - An unborn human or animal in the later stages of its development, but before birth.
Cancer - A disease in which some of the body's cells grow in an uncontrollable way. There are lots of different types of cancer.
Eugenics - The idea that human beings should be improved through genetic engineering. In the past, eugenics has generally involved killing people who are deemed “inferior”.