Mr Tony Rutherford, Chairman of the British Fertility Society, said:

“Mitochondrial diseases are a relatively rare but important group of conditions with an incidence varying between 1 in 4,000 to 1 in 10,000.  They are caused by mutations in the DNA that codes for mitochondria, the energy producing organelles in a cell.  An example is a condition known as MELAS (Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) which presents in childhood, and is associated with muscle weakness and discomfort, headaches, vomiting and seizures.  Most sufferers will have stroke-like episodes before middle age, which on a repeated basis can lead to loss of vision, issues with movement and dementia.  Mitochondrial disorders are inherited through the maternal cell line, and they usually occur when the majority of the mitochondrial DNA is abnormal.  Unfortunately at present, there are no cures for mitochondrial diseases, and the only treatment option is supportive therapy.

“This preliminary study outlines a possible method to prevent the transmission of mitochondrial disorders.  The female pronucleus, which carries the genetic message from the mother to the next generation, is removed from an egg that is known to carry a high percentage of mutated mitochondrial disease and transferred to a healthy donor egg, after its own genetic material has been removed.  This proof of concept study shows that transferring a pronucleus appears to be possible in human eggs, but more importantly it shows that this technique leaves the abnormal mitochondrial DNA behind, so that when the newly constructed fertilised egg cleaves to form an embryo, it uses the normal mitochondria from the donor egg.  Of course this study was performed on abnormally fertilised eggs and needs to be repeated in controlled conditions using healthy eggs to establish whether the technique is indeed viable in conditions closer to those employed in a clinical setting, and to demonstrate that the procedure is safe.  It is important to put this work into context, as it is only the first step on the long road to potentially developing a treatment to prevent the transmission of these dreadfully debilitating disorders.  The British Fertility Society supports such research and we look forward to seeing the results of more extensive studies in due course.”

Notes for editors:

The above statement was produced in response to a Nature advanced online publication: D Turnbull et al.,Pronuclear transfer in human embryos to prevent transmission of mitochondrial DNA disease. Published online 14 April 2010. DOI: 10.1038/nature08958.