It is estimated that 3,500 people in the UK have mitochondrial myopathies; a group of incurable mitochondrial diseases which, in the most severe cases, can cause debilitating and life-threatening muscle weakness. Life is made even more difficult for affected families as it is almost impossible to provide them with accurate genetic counselling and family planning advice.
Mitochondria are found in every cell in our body, except for red blood cells; they are the 'batteries' that provide energy to the cell. Mitochondria have their own small piece of DNA that is inherited only through the maternal line, so unlike most mutations in the chromosomes, mitochondrial DNA mutations are likely to be passed onto all offspring. Generally cells have a mixture of normal and abnormal mitochondria and the proportion of each determines the disease severity. The proportions are unstable and differ from egg to egg so it is very difficult to predict how severely a child will be affected. This makes the decision to have children a heart-wrenching gamble for families affected by mitochondrial disease.
In order to tackle these debilitating diseases, the Muscular Dystrophy Campaign has supported Professor Doug Turnbull's world-leading mitochondrial research at the University of Newcastle for the past 20 years, providing more than £1.2 million worth of funding in that time. This has culminated in the development of a technique with the potential to prevent mitochondrial diseases being passed from mother to child.
This technique involves replacing the faulty mitochondria with healthy mitochondria from a donated egg. This is done as part of the IVF process, either before an egg is fertilised (using a technique called maternal spindle transfer) or after fertilisation (pronuclear transfer). These techniques have proven successful (2, 3) at replacing the mitochondria in the laboratory.
If these techniques were to come into clinical practice they would give families affected by mitochondrial disease the opportunity to have healthy children. However, there is still work to be done before this could happen because although research on these techniques is allowed in the laboratory, the law currently prohibits implantation of any resulting embryos into the mother.
The Secretary of State for Health asked the Human Fertilisation and Embryology Authority (HFEA), in February 2011, to carry out a scientific review to scope 'expert views on the effectiveness and safety of mitochondrial transfer'. This review (4) concluded that as these techniques are so new, further experiments would be required before advice could be given as to whether the first clinical trials should be allowed to go ahead.
Encouragingly, it was announced last month that a new Wellcome Trust Centre for Mitochondrial Research (5) will be set up in Newcastle which will allow this research to move forward. Professor Turnbull will be the Director of the new centre and researchers will carry out the tests they hope will satisfy the HFEA that these techniques are safe and effective.
Secondly, the Government asked the HFEA and Sciencewise-ERC to seek the views of the general public on the possible use of these techniques in the clinic (6).
Mitochondrial transfer would seem to be an immediately controversial topic. News of research in the field is frequently greeted with newspaper headlines talking of 'three-parent babies' while fears are voiced over designer babies being the next step.
And yet, were these techniques to be put to use in the clinic, less than 0.1 percent of the resulting baby's DNA would come from the donated egg, and these genes would only be involved in energy production via the mitochondria, and nothing else. The techniques have been developed specifically for mitochondrial diseases, are not applicable to any other types of genetic conditions and cannot be used to alter the genes in the chromosomes. Therefore an important aspect of the HFEA's public consultation will be to communicate the complicated science involved to the public and raise awareness of its implications.The Muscular Dystrophy Campaign will be representing the patient voice during the public consultation to make sure the public are aware of the immense potential this technology has to help families at risk from mitochondrial myopathies. In the absence of a cure or treatment for these conditions, this technology currently has the amazing potential to transform lives by breaking the chain of inheritance within families.