Medical negligence solicitor Maria Panteli examines new treatments being developed to treat mitochondrial disorders

It is estimated that around 1 in 6,500 children born every year in the UK have a serious mitochondrial disorder.

Mitochondria are structures that provide human cells with the energy they need to function.

Mitochondria are present in almost all human cells. They generate the majority of a cell’s energy supply which power every part of our body.

Genetic faults in the mitochondria can cause serious and potentially fatal mitochondrial diseases which affect the organs and tissues that use the most energy including the heart, brain, muscles and liver. These can have devastating effects on the families that carry them.

Unlike nuclear genes, mitochondrial DNA is inherited only from mothers. A mother can carry abnormal mitochondria and be at risk of passing on serious disease to her child, even if she does not have any symptoms.

At present, treatment options are limited and there is no known cure, but include:

  • Vitamins, although there is limited evidence of their effectiveness.
  • Antioxidants which penetrate the membrane to try to improve mitochondrial dysfunction.
  • Spindle transfer, where the nuclear DNA is transferred to another healthy egg cell leaving the defective mitochondrial DNA behind, is a potential treatment procedure that has been successfully carried out on monkeys.  Using a similar transfer technique, researchers at Newcastle University have successfully transplanted healthy DNA in human eggs from women with mitochondrial disease into the eggs of unaffected women donors.  However, ethical questions have been raised regarding biological motherhood as the child receives genes from 2 different women.  

For those who know that they are at risk of having a child with a mitochondrial disease, the only options are:

  1. Adoption
  2. IVF with donor eggs
  3. Testing embryos during IVF - however this may not result in a disease-free baby, but lowers the chance of passing on the disease, and is not an option for some forms of mitochondrial disease
  4. Testing of the fetus during pregnancy with the option of termination - however, the sample tested may not accurately predict the risk of disease.

 For those who would like to have a genetically-related child without abnormal mitochondria, the only possible option is mitochondrial donation.

In July 2014, the Government announced its intention to allow the clinical use of 2 new treatments to prevent serious mitochondrial disease. Neither treatment has been used in humans and both were prohibited in the UK under the Human Fertilisation and Embryology Act 2008.

Controversy surrounds the new treatments and a number of concerns have been raised, importantly: Will the treatments be safe in all patients?

The treatments involve changes to the genetic material that will be passed on not only to the intended child, but also to subsequent generations of girls. Its use would, arguably, amount to inappropriate interference with the natural or spiritual aspect of reproduction, or give rise to arguments that any artificial or in vitro manipulation of embryos is unethical.

On 24 February 2015, the House of Lords voted to support the House of Commons to change the law to allow mitochondrial donation. The Human Fertilisation and Embryology (Mitochondrial Donation) Regulations 2015 were agreed despite a motion attempting to block their approval with 48 votes for and 280 against.

This statutory instrument makes provision to enable mitochondrial donation techniques to be used under licence as part of IVF treatment with the aim of preventing the transmission of serious mitochondrial disease from a mother to her child. In its simplest terms, the techniques involve replacing the unhealthy mitochondria in a woman who carries the disease, with the healthy mitochondria from a donor woman, during the process of IVF. The resulting baby would have all the genetic traits of the mother and father but would also have healthy mitochondria so would be free from disease.

The techniques are in an advanced stage of testing and the use of the procedure in humans is expected to begin within 2 years.