October 4, 2013

expert reaction to Council of Europe’s written declaration on mitochondrial DNA research

Professor Michael Hanna, Director MRC Centre for Neuromuscular Diseases at UCL Institute of Neurology, said:

“Mitochondria are small particles that produce energy in human cells- they can be likened to the “batteries” of a cell. Mitochondria have their own set of genes, called mitochondrial DNA, that are required solely for mitochondrial energy production. Genetic mutations in Mitochondrial DNA can cause fatal childhood and adult multisystem diseases for which there is currently no cure. Less than 1% of human genes are contained in mitochondrial DNA.  The vast majority of genes (99%) that determine human characteristics are located in a different place in the cell called the nucleus.

“The proposed technique, which requires further scientific study, will enable the mutated disease-causing mitochondrial DNA to be exchanged for normal mtDNA from a healthy donor. This would allow normal mitochondrial energy production and could prevent these diseases. It is correct that the 1%  of genes in mitochondrial DNA would be changed in this technique in order to enable normal energy production. However, the overwhelming majority of genes (99%) that determine human characteristics would remain unchanged.”

Prof Sir Ian Wilmut, Professor Emeritus, MRC Centre for Regenerative Medicine, University of Edinburgh, said:

“It is important that regulatory authorities take an informed decision on this matter, as indeed the HFEA has done. This simple procedure will make it possible for couples to have healthy children, who otherwise might not. Without this help there is a serious risk that the child will die or suffer serious illness.

“Just as there are inherited diseases as a result of abnormalities in chromosomal genes, other diseases occur because of errors in the genes within the mitochondria. We get our mitochondria from our mothers, in the egg that is fertilised to become an embryo. If the woman has mitochondria in which there are genetic errors then at present she knows that if she has a child it may be seriously ill. Simply by accepting an egg from a healthy donor the couple can be confident that this risk will be eliminated.

“The mitochondrial DNA is a very small proportion of the total DNA. As a result the only significant effect of using an egg from a donor is that the child will be healthy. In all other ways the child will be the child of the couple. I congratulate the potential parents, the donors and the clinicians and wish them speedy success.”