Babies born from three parents approved in UK

Three-person IVF, which prevents babies from inheriting lethal genetic diseases, has been approved by fertility regulator the Human Fertilisation and Embryology Authority (HFEA).

The first babies created from two women and one man could be born this time next year.

Babies born using the technique would receive a tiny amount of DNA from a third woman in addition to genes from its mother and father.

"It is a decision of historic importance. This is about cautious go ahead, not gung-ho go ahead and there is a long way to go. I'm sure patients will be really pleased by what we've decided today," said HFEA chair Sally Cheshire.

Under the rules, the authority will have to approve every clinic and every patient before the rare procedure can take place.

Three-person babies have been allowed in cases in the UK where the risk of a child developing mitochondrial disease is very high.

Clinics can now apply to the HFEA for a licence to conduct three-person IVF widely.

Doctors in Newcastle - who developed the advanced form of IVF - are expected to be the first to offer the procedure and have already appealed for donor eggs.

Some families have lost multiple children to incurable mitochondrial diseases, which can leave people with insufficient energy to keep their heart beating.

The diseases are passed down from only the mother, hence the technique uses a female donor egg.

The resulting child has a tiny amount of their DNA from the donor.

The move has proved controversial with some questioning its implications on so-called genetically-modified designer babies.

David King, from the campaign group Human Genetics Alert, said: "This decision opens the door to the world of genetically-modified designer babies.

"Already, bioethicists have started to argue that allowing mitochondrial replacement means that there is no logical basis for resisting GM babies, which is exactly how slippery slopes work."

However, proponents of this technique highlight its many positives.

"This historic decision will open the door to the first licensed treatments being offered. We know of many women who have faced heartache and tragedy and the sorrow of stillbirths, while trying to start their own family, and this decision gives them new hope and choice for the first time," said Robert Meadowcroft, from the charity Muscular Dystrophy UK.

Just 0.1 per cent of a person's DNA is held in the mitochondria. 

It is always inherited from the mother and has no influence over individual characteristics such as appearance and personality. Mitochondrial disease is caused by defective mitochondria – the tiny structures in nearly every cell that convert food into useable energy.

Thousands of children worldwide are born with such severe symptoms they develop muscle weakness, blindness, deafness, seizures, learning disabilities, diabetes, heart and liver failure.

It is often fatal. The aim of the new procedure is to get the healthy mitochondria from the donor.