A clinic in Newcastle has been granted the first licence for controversial "three-parent baby" mitochondrial replacement therapy.
The licence allows fertility doctors to prevent inherited disease by creating a baby with three genetic parents.
A woman, who has not been named, is going to have the treatment at the Newcastle Fertility at Life clinic.
Doctors will aim to stop her passing on defective genes in the mitochondria, tiny power plants in cells that supply energy.
The procedure involves giving her an IVF baby with DNA from three individuals, and it is highly controversial.
Nuclear DNA will be given to the child from the mother and father that define key characteristics such as personality and eye colour.
It will also have a tiny amount of mitochondrial DNA provided by a female donor – the third parent.
Approval for the treatment was announced by the Human Fertilisation and Embryology Authority (HFEA) at its annual meeting in London.
A spokesman for the regulator said: The treatment for this patient, whose details I cannot discuss, has been given the go ahead.
Britain is the first country in the world to allow mitochondrial replacement therapy after the HFEA gave a cautious green light to the procedure last year.
MPs and peers voted in 2015 to allow it under the Human Fertilisation and Embryonic Act which sets the legal framework for fertility research and treatment.
Tampering with germline inherited DNA is normally illegal, but MRT has been made an exception.
Scientists at the University of Newcastle have worked with the fertility clinic to develop the procedure, and a number of patients are understood to be lined up for treatments which are expected to start this spring.
The procedure is carried out by transferring the genetic material that effectively encodes a baby’s identity to a donor egg whose own nuclear DNA has been removed.
Two different techniques may be employed, either before or after fertilisation.
The end result is the same, producing an embryo containing healthy mitochondria from the donor and nuclear DNA from the baby’s mother and father.
Mitochondria only hold about 0.1% of a person’s DNA, which is always inherited from the mother.
The results can be catastrophic if mitochondrial DNA goes wrong – leading to a wide range of potentially fatal conditions including heart problems, liver failure, brain disorders, blindness and muscular dystrophy.
The aim of the new treatments is to prevent the faulty genes being passed to future generations, potentially eliminating such terrible diseases forever.
Mary Herbert, professor of reproductive biology at the Newcastle Fertility Centre and the University of Newcastle, said: Many years of research have led to the development of pro-nuclear transfer as a treatment to reduce the risk of mothers transmitting disease to their children.
Critics say the techniques are the first step down a slippery slope leading to designer babies and eugenics.
An initial £8m is being made available by the NHS to fund the treatments over the next five years.
Mitochondrial diseases are incurable conditions passed down the maternal line – affecting about one in 6,500 children worldwide.
(c) Sky News 2017: Newcastle clinic granted licence for ‘three-parent baby’ therapy