The government's fertility regulator has launched a public consultation to gauge people's attitudes towards controversial new medical procedures designed to avoid serious genetic diseases.
The techniques are contentious because they produce IVF embryos that carry DNA from both parents and a healthy female donor, and use a form of genetic modification that passes the donor's DNA on to future generations.
British law prohibits such genetic modification of embryos, but the legislation may be rewritten as early as next year after a parliamentary debate that will be informed by the Human Fertilisation and Embryology Authority's consultation.
About 12,000 people in Britain live with diseases caused by glitches in the genetic material held inside tiny powerplants called mitochondria that sit within most cells. The DNA in mitochondria controls how cells make and use energy, while a person's appearance and other characteristics are influenced by the genetic material locked up in the cell nucleus.
Faulty mitochondria can cause a wide range of devastating disorders that typically affect the organs and tissues that use most energy, such as the brain, heart and muscles. About one in 200 people carry some form of mitochondrial mutation, and while some of these cause no or only mild disease, others underlie disorders that are progressive and ultimately fatal.
Mitochondria are passed down to children only from their mothers, so to avoid harmful mutations being inherited, the new techniques aim to replace the mother's mitochondria with healthy versions from a donor. There are only 37 genes in mitochondria, about 0.2% of our total genetic makeup.
In one procedure, called maternal spindle transfer, doctors use standard IVF techniques to collect eggs from the affected woman. They then remove the nucleus from one of her eggs and drop it into a healthy egg from a donor that has had its own nucleus taken out. The new egg, which carries all the mother's chromosomes but the donor's mitochondria, is then fertilised with the father's sperm.
The second procedure, called pronuclear transfer, is similar but performed on an early-stage embryo instead of an egg.
Through online questionnaires on the authority's website, public meetings in London and Manchester, and opinion polls, the HFEA hopes to gather views on the procedures for a report that will go to Jeremy Hunt, the health secretary, in the spring. The consultation runs from Monday until 7 December.
"If this is allowed, and we don't have a view, it has consequences in perpetuity," said Lisa Jardine, chair of the regulator. "Once we have genetic modification we have to be damn sure we're happy, because this is not about us, our children, or even our grandchildren, it's about many generations down the line, what the consequences might be."
The procedures are still being developed in laboratories, notably by Doug Turnbull and others at Newcastle University. Any change in the law would allow the treatment in principle, with clinics then requiring permission from the HFEA or another regulatory body.
One issue the consultation will ask about is whether a donor should be anonymous, as with blood donation, or contactable by children they contributed DNA to, as is the case with sperm and egg donation. What the procedures mean for the child's sense of identity and the issue of genetic modifications that will run through countless generations will also be explored.
"We want to make a difference to the lives of our patients who live with mitochondrial diseases. These can seriously affect the quality of life of both patients and their families and it often affects several generations. If we can stop that happening, it will be a tremendous help for many hundreds of people who suffer with these diseases," said Mary Herbert, professor of reproductive biology, who works with Turnbull at Newcastle.
"We are now undertaking experiments to test the safety and efficacy of the new techniques and hope that this will inform the HFEA's decision-making process. This work may take three to five years to complete," she added.
