Fertility regulator to decide whether to allow 'three-parent baby' treatments

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Britain's fertility regulator is meeting to decide whether or not to give the green light to so-called "three-parent baby" treatments for inherited diseases.

If the proposal is approved by the Human Fertilisation and Embryology Authority (HFEA), the first mitochondrial replacement therapy (MRT) patients could be treated as early as next spring.

Scientists at the University of Newcastle, which has pioneered the treatments, say they already have women lined up for the therapy.

The team hopes to treat up to 25 women a year with NHS funding.

IVF babies born after MRT would receive a tiny amount of DNA from a third person besides their mother and father, an egg donor.

Fertility doctors carrying out the treatment will aim to replace abnormal genes in the mitochondria, rod-like power plants in cells that generate energy.

Mitochondria only hold around 0.1% of a person's DNA, which is always inherited from the mother and has no influence over individual characteristics such as appearance and personality.

It is quite separate from the DNA in the cell nucleus which houses the vast majority of an individual's genes. But faulty mitochondrial DNA (mtDNA) can lead to a wide range of potentially fatal conditions affecting vital organs, muscles, vision, growth and mental ability.

The board members of the HFEA meeting in London will decide whether clinics should be free to apply for permission to carry out the treatments.

Every patient would have to be considered separately before a licence allowing the therapy is issued by the regulator.

An independent panel of experts has recommended "cautious adoption" of MRT.

The treatment 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 - an embryo containing healthy mitochondria from the donor and nuclear DNA from the baby's mother and father.

In theory, mitochondrial replacement can not only prevent a child developing inherited diseases, but also protect future generations.

Last year, the UK became the first country in the world to legalise mitochondrial replacement after MPs and peers voted in favour of allowing it.

Critics say the technique is not fool-proof and small numbers of faulty mitochondria may still be "carried over" into the child, and even replicate in the developing embryo.

They also argue that unforeseen problems might occur once the procedure is used to create human babies. For instance, replacing mtDNA might have more of an impact on personal traits than has been envisaged.

Unknown epigenetic effects - environmental influences that alter the way genes work - may also have serious consequences for the health of babies, it is claimed.