September 19, 2013

expert reaction to mitochondrial replacement and evolution

Authors of a comment piece in Science raised their concerns about the proposition to introduce new IVF techniques into the clinic which would tackle genetic disease by replacing the faulty mitochondrial DNA of mothers.

Professor Doug Turnbull, Professor of Neurology and Director of the Wellcome Trust Centre for Mitochondrial Research, Newcastle University, said:

“Like every new medical technique, mitochondrial replacement will carry some risks when first used to treat patients. We welcome discussion of these and agree that families affected by mitochondrial disease should be fully appraised of the best science, so they can judge uncertain risk from the procedure against the known high risk of having a child with a devastating disease. They will also consider the likely benefits of mitochondrial replacement, which we are pleased that the authors of this commentary acknowledge.

“We do not agree that the concerns raised by the authors have been overlooked, or that they present a compelling argument against clinical use. The experiments they cite have methodological weaknesses that limit their relevance to humans, or have been superseded by more exhaustive research.

“The suggestion that proof-of-principle experiments in macaques involved closely-related animals is especially misleading. Data in the original paper report that the macaques involved in this work were unrelated, with substantial differences between the mitochondrial genomes of these animals.

“The authors nonetheless make sensible suggestions about managing risk by matching donated mitochondria to the mother’s as closely as possible. This will often be simple to achieve and is already in our plans.

“It is critical that all risks, however small, are independently assessed and weighed against probable benefits before mitochondrial replacement is approved for clinical use. The proper forum for this assessment will be the expert HFEA licence committees that decide whether the techniques are safe enough to be offered to patients, should Parliament agree that they are ethically acceptable.”

Professor Robin Lovell-Badge, Head of Developmental Genetics, MRC National Institute for Medical Research, said:

“The authors of the commentary highlight some interesting (although not novel) concepts to do with evolution of mitochondrial DNA sequences and the obvious conflict present due to mitochondria being inherited only from females, which means effectively that it is not in their “interest” to promote male survival or fertility. However, this is almost certainly of little relevance within a freely interbreeding species such as humans, and it is of even less relevance when talking about using “mitochondria replacement” techniques to allow a few individual women to have healthy rather than desperately ill children.”

‘Mitochondrial replacement, evolution, and the clinic’ by Klaus Reinhardt et al. published in Science, on Thursday 19 September 2013.