British scientists have welcomed a decision by the country's embryology watchdog last week (September 8) to permit a research group to try preventing the transmission of mitochondrial diseases, such as mitochondrial myopathies, from mother to child, using pronuclear transfer.
A team led by Doug Turnbull and Mary Herbert at the Newcastle Fertility Centre now have a green light to investigate the feasibility of moving pronuclei from the fertilized egg of a woman with mitochondrial disease to the egg of another woman, producing an embryo with the nuclear DNA of a man and a woman, and the mitochondrial DNA of another woman. The researchers will use donated fertilized eggs for the study and will not let any resulting embryos develop into a child.
Their initial application to the Human Fertilisation and Embryology Authority (HFEA) for permission to conduct the research was rejected in September 2004. "When the initial application came in it was rejected not because of the research itself, but because the committee had interpreted the Human Fertilisation and Embryology Act and considered that what they were planning to do was forbidden," an HFEA spokeswoman told
The Act, which dates to 1990, forbids "altering the genetic structure of any cell while it forms part of an embryo, except in such circumstances (if any) as may be specified in or determined in pursuance of regulations."
In 2001, Jason Barritt and colleagues from the Institute for Reproductive Medicine and Science of St. Barnabas in West Orange, NJ, reported successfully using ooplasm transfer to correct mitochondrial disease, leading to the birth of 15 healthy children. At the time, the HFEA called the report an unwelcome development, telling the BBC it decided not to allow the technique in the United Kingdom because it involved the possible alteration of the human germline.
The Newcastle scientists challenged the HFEA ruling in November last year, and were again turned down. Then, in the second stage of the appeal process in April this year, a new group of HFEA members received extra evidence from several outside experts on the genetics behind the research, the processes the research would involve, and how the HFE Act should be interpreted. After hearing the further evidence, committee members decided this month that the research proposed by the group did not contravene the Act, and permitted it.
Azim Surani, professor of physiology and reproduction at the University of Cambridge, welcomed the HFEA's decision, saying the technique offers a real hope of treatment for patients with mitochondrial diseases. It is likely to be more efficient than somatic cell nuclear replacement, he pointed out. "When you put an adult somatic nucleus in an egg, you have to reprogram it and ask it to go back in time, if you like," he told
Peter Braude from King's College London said he was delighted to hear the work will be pursued in the United Kingdom. "Performing the research using donated eggs will help [researchers] understand whether the process is achievable and safe," he said in a statement. "If it works and is safe it will be the answer to the prayers of those inflicted with these awful mitochondrial genetic disorders."
Turnbull and Herbert's application says that one of the aims of their research will be to monitor possible carry-over of mitochondria between eggs. "I think you would make the assumption that you would bring a small number of mitochondria over," Surani noted. "But the hope might be that the mitochondria from the donated egg would compensate."
Just last month, the British government began a public consultation exercise on the Human Fertilisation and Embryology Act with a view to revising it. At the launch of the consultation, the government indicated that it would be useful to change the law to allow mitochondrial disease. "That would be great news for us," Alison Murdoch from the Newcastle center told
The HFEA spokeswoman stressed, however, that experts based their decision to approve the experiment solely after interpreting the law in its current form. "Until any real changes are made, we will be governed by the Act as it is," she said.
At press time, neither Turnbull nor Herbert could be reached for comment.