THE Church of England is not against mitochondrial replacement, which could "bless many"; but is nervous that not enough is known about it, the Bishop of Swindon, Dr Lee Rayfield, said on Tuesday.
MPs voted in favour of the draft regulations permitting the techniques to be used by 382 to 128 on Tuesday afternoon.
Writing in The Sun on Tuesday morning, Dr Rayfield sought to correct the impression that the Church was trying to "put the brakes on progress".
"There are still questions around safety and efficacy," he wrote. "The Church of England wants to ensure that these are answered as well as possible before the technique is permitted. . .
"Our desire in the national Church is for mitochondrial replacement to bless many and provide an answer to their deepest hopes and prayers for generations to come."
Reports that the Church opposes the technique - provoking an angry reaction from some MPs and scientists - emerged after the circulation of a statement from the Church's national adviser on medical ethics, the Revd Dr Brendan McCarthy, on Friday. This said that the law should not be changed, "until there has been further scientific study and informed debate into the ethics, safety and efficacy of mitochondrial replacement therapy".
Speaking on the Today programme on Radio 4 on Tuesday, Dr Rayfield expressed regret about the Church's communication of its position.
"I'm not going to come out against this, because I think this hasn't been our finest hour for the Church of England, at least, in getting our message across," he said. "We seem to have been heard as stressing some of the caution so much, that we've only been heard as anti."
The Church's position was "nuanced", he argued. Some members, "like myself, are more confident than others". Others had concerns about "Is this the right time? And how is the legislation going to work out? And really to raise the fact that this is a massive step for us." He spoke of "a number of concerns about the safety and efficacy" of treatment.
Dr Rayfield was a member of the Human Fertilisation and Embryology Authority (HFEA) group overseeing the public consultation on the technique. On Today, Professor Lisa Jardine, who chaired the HFEA from 2008 until January 2014, accused the Church of reneging on its earlier support for the technique.
"I don't know where the Church of England has been - it was in all of our discussions since 2011," she said. "Whether they weren't listening, I don't know, but the fact is they've gone along with the process and then suddenly they are concerned way after the event." It safety concerns were a "red herring", she said.
The Church's division for Mission and Public Affairs (MPA) has, indeed, expressed consistent support "in principle" for the techniques, but has been cautious about whether enough is known about them.
In its response to the Department of Health consultation on draft regulations in May last year, it called for "more research into the safety and efficacy of mitochondrial replacement therapy".
A consultation response issued the previous year noted a number of detailed concerns.
"We are uncertain that enough is, as yet, known about the roles that mitochondria play. . . If it can be demonstrated, beyond reasonable doubt, that mitochondria play no part in the transmission of hereditary characteristics, a change in the law is, in our opinion, permissible. If mitochondria do play a role greater than that currently understood, further consultation would be necessary before any change in the law ought to be considered."
The submission also noted that research into the techniques, and the techniques themselves, will require the destruction of embryos, causing "ethical problems for some people".
The HFEA argues said that the "public dialogue exercise" it conducted indicated that there was "general support" for permitting the technique (News, 2 January). An expert scientific panel, convened to review the safety of the technique, concluded that there was no evidence to show that it was unsafe.
If approved by Parliament - the House of Lords will now consider the regulations - the techniques would for the first time permit the transfer of genetically modified embryos into the womb. The UK would become the first country in the world to permit the creation of babies with DNA from three people.
The techniques have been developed to enable women who suffer from a form of mitochondrial disease, caused by faults in the DNA of mitochondria (often described as the human cell's batteries), from passing it on to their children. It is estimated that this could help 150 couples a year. About one child in 200 is born each year with a form of mitochondrial disease. Most cases are mild or asymptomatic. About one in 6500 is estimated to develop a more serious, even fatal, mitochondrial disorder.
IVF is used to fertilise a mother's egg, containing "unhealthy" mitochondria, with the father's sperm. The nucleus of the fertilised egg is then collected and transplanted into a donor egg containing healthy mitochondria, but with its own nucleus removed.
More than 99 per cent of the child's genes would come from the mother and father, while less than one per cent would be inherited from the donor. This change would affect the germ line, meaning that the donor's mitochondrial DNA would be passed on to future generations.
Germ-line modifications have never been permitted on embyros before. The UN's Universal Declaration on Human Genome and Human Rights describes the human genome as "the heritage of humanity", and gives the International Bioethics Committee a duty to identify "practices that could be contrary to human dignity, such as germ-line interventions".
In addition to safety concerns, some opponents of the techniques have expressed concerns about the ethics involved, including questions of identity. Draft regulations state that those who donate mitochondria will remain anonymous so that the children created will not be able to trace them.
In September, an editorial in the New Scientist highlighted new research that suggested that "we may have seriously underestimated the influence that mitochondria have. Recent research suggests that they play a key role in some of the most important features of human life. This raises the ethically troubling prospect - once widely dismissed, including by this publication, that children conceived in this way will inherit vital traits from three parents."
The vote in the House of Commons today was free. On Tuesday, Andrew Miller, who chairs the Commons science committee, told The Guardian: "It is utterly outrageous in a free society for the Churches to tell parents who are in this painfully difficult position that they cannot undergo procedures like this . . .
"We need to keep our eyes firmly focused on the pain and suffering of the families that have seen children die at a young age, or are having to make serious decisions in their lives. Their needs must trump everything."