Most people would be happy to see the law changed to allow a radical form of gene therapy on the IVF embryos of women in danger of passing on mitochondrial disease to their babies – a potentially severe and fatal metabolic disorder.
An exhaustive survey of public attitudes to the replacement of an affected mother’s mitochondria – the tiny “power packs” of cells – with those from an egg donor has found widespread support for the technique.
A series of public consultations on mitochondrial replacement, which will result in IVF babies effectively inheriting genetic information from three biological parents, has found that most people would support its legalisation in order to help families at risk of the genetic disorder.
“We’ve found that there is broad support for permitting mitochondria replacement to give families at risk of mitochondrial disease the chance of having a healthy child,” said Professor Lisa Jardine, the chair of the Human Fertilisation and Embryology Authority (HFEA), which was charged by the Government to investigate public attitudes to the technique.
“Although some people have concerns about the safety of these techniques, we found that they trust the scientific experts and the regulator to know when it is appropriate to make them available to patients,” Professor Jardine said.
David King, director of the pressure group Human Genetics Alert, criticised the HFEA for ignoring the potential risks associated with the technique, which has had only limited testing on laboratory animals and is not medically practised anywhere in the world.
“These techniques go far beyond anything existing in both invasiveness to the embryo and complexity so it’s not surprising that they pose serious health risks to the child, risks that the HFEA refuses to properly address,” Dr King said.
Mitochondrial replacement involves fusing the egg-cell nucleus of the affected mother with an egg cell from an unaffected donor. The donor egg has its own nucleus and its complement of chromosomes removed, but retains the donor’s healthy mitochondria – which have their own DNA to control energy use within the cell.
Some form of mitochondrial disease affects around 1 in 200 children born each year, but severe symptoms occur in only about a few dozen new-born infants. The disease results from defects in the mitochondrial DNA, but scientists believe these could be prevented by the technique of mitochondrial replacement from a donated egg cell.
After the egg cell of mother and donor is fused and fertilised by IVF it is implanted into the mother’s womb in the usual way. The resulting baby should be free of the mother’s mitochondrial defects and subsequent generations should also be free of mutations in the mitochondrial DNA – a form of “germ-line” gene therapy.
The law covering IVF, the Human Fertilisation and Embryology Act, does not allow germ-line gene therapy, when the sperm or eggs are genetically altered, or the genetic modification of IVF embryos. However, in 2008 the Act was amended to allow the Secretary of State for Health to permit techniques that prevent the transmission of mitochondrial disease.
In January 2012, the Government asked the HFEA to seek views on mitochondrial replacement before it was made legal. As a result, the authority commissioned a series of public consultations, involving workshops, face-to-face interviews, surveys, questionnaires and focus groups.
“Overall, participants were fairly positive about the techniques, seeing them as a way of offering parents the chance to have a healthy child that is genetically their own,” says the HFEA’s report published today.
“Some participants suggested that the use of these techniques might be seen as ‘playing God’ and could result in a ‘slippery slope’ to ‘designer babies’ and ‘aborting disabled people’,” it says.
“Others raised concerns about the safety of the new techniques, and wanted to know about the risks involved and whether research has been carried out in terms of success rates and long-term safety,” the report adds.
A scientific assessment of the safety of mitochondrial replacement found no major concerns but has recommended further studies to ensure that the technique does not result in long-term harm to either the baby or to subsequent generations.
The assessment, by a panel of experts, also found no evidence to support the fear that switching genetic material from one egg cell to another would result in changes to the way genes behave in a different cell – so-called epigenetic changes.
“While the panel cannot rule out the possibility of epigenetic alterations...there is no evidence at present that such alterations have a significant or far reaching effect on development or health,” the scientific assessment says.
However, Dr King said that not enough research has been done on the risk posed by epigenetic alterations to be sure of the safety of mitochondrial replacement.
There are two methods of carrying out mitochondrial replacement. One involves switching the nucleus from the mother’s egg cell before fertilisation, called maternal spindle transfer, while the other involves switching the nucleus after fertilisation, called pro-nuclear transfer, which would result in the destruction of the donor’s embryo.
A minority of people who took part in the survey objected to this second technique because it involved the manipulation and disposal of a human embryo, which they felt would be objectionable to religious groups, such as the Catholic Church.