09 June 2014
ByAppeared in BioNews 757
Mitochondrial replacement (MR) involves transferring genetic material from a fertilised or unfertilised egg cell with faulty mitochondria into a healthy, denucleated egg cell provided by a donor, effectively creating embryos with genetic material from three people.
Mitochondria primarily provide the energy needed in each of the body's cells to enable them to function. Mutations in mtDNA (mitochondrial DNA), however, which only accounts for one percent of a person's genetic code, can cause debilitating and often fatal diseases. As mtDNA is exclusively inherited from the mother, women with disease-causing mutations within their mitochondria are at risk of passing on health problems their children.
The report was the HFEA's third review of the safety and efficacy of MR techniques being developed to prevent the transmission of serious mitochondrial disease.
It found that the two MR techniques being developed, maternal spindle transfer and pro-nuclear transfer, were potentially useful for a 'specific and defined group of patients', namely those with unhealthy mitochondria at risk of passing on health problems and who want to have genetically-related children.
The evidence reviewed 'did not suggest these techniques were unsafe', the report concluded, a finding also made in the previous two reviews. It also found that research into MR had 'progressed well' but that there are still a number of experiments that needs to be carried out before treatments are offered to patients.
Professor Robin Lovell-Badge, from the Medical Research Council and a member of the scientific panel, said: 'The direction of travel still suggests that it is all safe, but we don't know what's round the corner so we're being a little cautious'.
However, scientists have argued that the mitochondrial DNA will have no impact on the characteristics of the embryo apart from the function of the mitochondria itself, and thus does not constitute a form of 'eugenics'.
Dr Andy Greenfield, the panel chair, addressed these concerns saying: 'This is not eugenics [...] eugenics it seems to me invokes preventing some individuals being born. [...] These technologies will allow women to have genetically related and healthy children'.
Even if MR techniques are proven to be safe, as the technique involves changing the DNA of a human embryo, their use remains prohibited under UK law. However, Parliament is able to pass regulations to permit the technique under the governing legislation.
The UK government has in principle backed the use of MR and has conduced a consultation on draft regulations (reported BioNews 744). The chief medical officer, Professor Dame Sally Davies, commented last year, 'It's only right that we look to introduce this life-saving treatment as soon as we can'.
Sally Cheshire, chair of the HFEA, said: 'Now it is a question for others. If the Government decides to seek to change the law they will need the approval of both Houses of Parliament, and it is only right that they consider all the ramifications, social as well as medical, before they make up their minds.
'There is a long way to go yet'.
Sarah Norcross, the director of the Progress Educational Trust, which publishes BioNews, said: 'The scientific review committee have given a considered thumbs up to allowing techniques to avoid the transmission of inherited mitochondrial disease to be used in clinic.
'We therefore urge the Government to press ahead and pass regulations to allow families blighted by mitochondrial disease to benefit as soon as possible'.