UK Government backs mitochondrial replacement

Dr Rosie Morley

Progress Educational Trust

07 July 2013

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[BioNews, London]

The UK Government is to support the introduction of mitochondrial replacement therapy. The IVF-based procedure could allow women with mitochondrial disease the opportunity to have healthy children, by replacing their own, faulty mitochondria with healthy mitochondria from a donor.

The Chief Medical Officer, Dame Sally Davies, said: 'What we are starting to do now is to develop the regulations, consult on these regulations and then to take them into Parliament… I hope then to go forward and we'll be the first country if we do'.

UK law currently prohibits a genetically altered human embryo from being implanted into a woman, but the Secretary of State has the power to introduce regulations to permit treatment in specified circumstances for the prevention of serious mitochondrial disease. The draft regulations would need to be approved by both Houses of Parliament before they can become law.

Mitochondrial DNA replacement techniques have raised a number of ethical considerations, because they require the use of genetic material from a third person, the mitochondrial DNA donor, leading to children born with genetic material from three people. Furthermore, replacing diseased mitochondria with healthy ones would be a change that would be passed on to subsequent generations. This could constitute a form of germ-line therapy.

However, Professor Davies explained that it is only the germ-line of the mitochondria that is passed down to future generations, which is quite separate from the DNA of the nucleus that 'makes us what we are'. 'There is no intention of doing anything with the nuclear DNA', she said.

The UK's Human Fertilisation and Embryology Authority, which supports the introduction of regulations to Parliament, advised the Government there is no scientific evidence to suggest the proposed techniques are unsafe. It also conducted a public consultation in 2012 that showed broad support for the treatment. A review by a British Medical Association's medical ethics committee last year also decided that the treatments were ethical and should go ahead, as long as research suggests they are likely to be safe and effective. The Nuffield Council on Bioethics also concluded that the future use of and continued research into such treatments would be ethically permissible.

Professor Alison Murdoch from Newcastle University, which is leading the way with research into mitochondrial replacement therapy, said in the Independent: 'This is great news for UK science and gives hope to women who just want a healthy baby. The UK Government has made a moral decision. There is still more research to do, but this decision means that we could eventually be allowed to offer it as a treatment'.

There are currently two mitochondrial replacement techniques in development, both of which involve transferring the nuclear DNA of the future parents into a donor egg containing healthy mitochondria. 'Pronuclear transfer' involves taking the nucleus of a fertilised egg containing DNA from both the father and mother, and transferring it into a donor egg in which the nucleus has been removed. In the alternative method, 'maternal spindle transfer', the mother's DNA is transferred to the donor egg before it is fertilised. The treatments have been shown to be effective in animals but could not be fully tested in humans without changes made by Parliament.

Speaking to The Guardian, Professor Robin Lovell-Badge from the National Institute for Medical Research said, 'it will of course be a brave decision for the first families, and for the HFEA as the regulator, to decide to go ahead once the regulations are approved by Parliament, but more often than not, progress requires some element of bravery'.

Sarah Norcross of the Progress Educational Trust, the organisation that publishes BioNews, said: 'UK scientists are leading the way with their research to avoid inherited mitochondrial diseases and the UK Government is emulating them'.

'The combination of the regulatory framework already in place for IVF and the public support for the techniques to be allowed means that the Government can act confidently and quickly and not impede scientific progress from delivering its promised benefit', she added.

The regulations are due to be debated in Parliament next year.

Reproduced with permission from BioNews, an email and online sources of news, information and comment on assisted reproduction and genetics.