Monday September 17 2012
Most genes would come from the parents with 1% from a donor
What is the issue?
“Regulator asks public whether to allow ‘three parent families’,” The Independent reports after the Human Fertilisation and Embryology Authority (HFEA) – which regulates the use of fertility treatments and research in the UK – said it wanted to hear public views on a new fertility treatment.
The HFEA wants to gather public opinions on mitochondrial replacements, a controversial fertility treatment that the HFEA concedes is “at the cutting edge, both of science and of ethics” because it uses genetic material from three people.
Almost all of the genetic material in our bodies is contained in the cell nucleus that contains 23 chromosomes inherited from our mother and 23 inherited from our father. However, there is also a small amount of genetic material contained in cellular structures called mitochondria, which produce the cell’s energy. Unlike the rest of our DNA, this small amount of genetic material is passed to the child only from the mother. There are a number of rare diseases caused by mutations in the genes in the mitochondria. Women carrying these mutations will pass them directly to their child, with no influence from the father.
The IVF technique being considered aims to prevent these “mitochondrial diseases” by replacing the mother’s mitochondria with healthy mitochondria from a donor, thereby creating a healthy embryo. This would mean that the child would have the genetic material of three people – the majority still from the mother and father, but with around 1% of mitochondrial DNA coming from a donor.
What is the HFEA?
The Human Fertilisation and Embryology Authority (HFEA) is an independent organisation that licenses and monitors all fertility clinics in the UK. It regularly inspects clinics to ensure they adhere to government safety and ethical standards. The HFEA is also responsible for regulating UK research that involves human embryos, and all such research projects must apply for a licence from the HFEA. The organisation aims to provide the public with impartial information on fertility issues and techniques. To ensure that reviews into fertility treatments are objective and independent, the chair, deputy chair and at least half of HFEA members must not be doctors or scientists involved in human embryo research or fertility treatment.
The HFEA is currently conducting a review into “scientific methods to avoid mitochondrial disease”.
In 2008 an amendment was made to the Human Fertilisation and Embryology Act (1990) to “allow regulations to be passed that will allow techniques, which alter the mitochondrial DNA of an egg or embryo, to be used in assisted conception to prevent the transmission of serious mitochondrial disease”. However, the regulations would only be passed if it was clear that the scientific procedures involved were safe and effective. Mitochondria replacement techniques are currently legal only for research purposes, and cannot be used for treatment.
In early 2011, at the request of the health secretary, the HFEA set up a small panel with wide-ranging expertise to collect and summarise scientific evidence on mitochondria techniques. Later in 2011 the HFEA submitted the panel’s findings to the Department of Health, which was considering setting up a public consultation on whether or not to introduce the regulations.
Today, the HFEA said it had been asked by the government to seek public views on whether mitochondria replacement techniques should be made available to couples at risk of having a child affected by serious mitochondrial diseases.
Professor Lisa Jardine, chair of the HFEA said: “The government has asked us to take the public temperature on this important and emotive issue.
“The decision about whether mitochondria replacement should be made available to treat patients is not only an issue of great importance to families affected by these terrible diseases, but is also one of enormous public interest. We find ourselves in uncharted territory, balancing the desire to help families have healthy children with the possible impact on the children themselves and wider society.”
What is mitochondria replacement?
There are two IVF mitochondria replacement techniques currently at the research stage, called pronuclear transfer and spindle transfer. These are the techniques under debate.
Pronuclear transfer involves an egg during the process of fertilisation. In the laboratory, the nucleus of the egg and the nucleus of the sperm, which have not yet fused together (the pronuclei) are taken from the fertilised egg cell containing the “unhealthy” mitochondria and placed into another donor fertilised egg cell which has had its own pronuclei removed. This early stage embryo would then be placed into the mother’s body. The new embryo would contain the transplanted chromosomal DNA from both of its parents, but would have “donor” mitochondria from the other egg cell.
The alternative mitochondria replacement technique of spindle transfer involves egg cells prior to fertilisation. The nuclear DNA from an egg cell with “unhealthy” mitochondria is removed and placed into a donor egg cell which contains healthy mitochondria and has had its own nucleus removed. This “healthy” egg cell can then be fertilised.
Neither pronuclear transfer nor spindle transfer are currently permitted as treatments; they can be used only for research purposes.
Only one method to try to prevent mitochondrial diseases is currently licensed. Called “preimplantation genetic diagnosis” (PGD), the technique assesses the mitochondrial DNA content in a very early stage embryo to see whether it would give rise to disease in the child. PGD is currently licensed by the HFEA for the prevention of a number of mitochondrial diseases, and differs from the techniques under review as it doesn’t alter the nuclear or mitochondrial DNA of the embryo. PGD can reduce, but not eliminate, the possibility of mitochondrial disease.
Pronuclear transfer and spindle transfer are said to be potentially useful for the few couples whose child may have severe or lethal mitochondrial disease, and who would have no other option for having their own genetic child. It is estimated that, in the UK, around 10 to 20 couples a year could benefit from these treatments.
How many children does mitochondrial disease affect?
The HFEA reports that around 1 in 200 children are born each year with some form of mitochondrial disease. Some of these children will have mild or no symptoms, but others can be severely affected – with symptoms including muscle weakness, intestinal disorders and heart disease – and have reduced life expectancy.
What ethical concerns have been raised about the techniques?
There are obvious ethical implications from creating an embryo with genetic material from three parents.
Among the questions raised are:
- Should the details of the donor remain anonymous or does the child have the right to know who their “third parent” is?
- What would be the long-term psychological effects on the child knowing it was born using donated genetic tissue?
Opponents of these types of treatments cite what can be broadly summarised as the “slippery slope” argument; this suggests that once a precedent has been set for altering the genetic material of an embryo prior to implantation in the womb, it is impossible to predict how these types of techniques might be used in the future.
Similar concerns were raised, however, when IVF treatments were first used during the 1970s; today IVF is generally accepted.
How do I make my views known?
The HFEA has launched a consultation website that explains the science and ethical issues in different ways, including with videos and downloadable discussion packs. Anyone can either register their views online or attend one of two free consultation events to be held in November. The findings of the review and public consultation are due to be reported to the Department of Health in March 2013.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on twitter.