May 15, 2019

expert reaction to a correspondence piece “mitochondrial donation — which women could benefit?”

Reactions to a piece published in NEJM which discusses which women stand to benefit from mitochondrial donation. 

Dr Hansong Ma, Group Leader and Wellcome Sir Henry Dale Fellow at the Wellcome Trust/ Cancer Research UK Gurdon Institute said:

“This is an interesting and useful study which gives a nice overview about the mother-child pair transmission of a certain mtDNA mutant. 

“The whole prediction is based on mutant mitochondrial DNA level in the blood sample of the mother-child pairs. I think that it is known that the heteroplasmic level in blood cells does not necessarily reflect the heteroplasmic level in oocytes or other tissues. People who suffer from mitochondrial diseases usually have their primary symptoms coming from muscle and nervous system, where there is a high energy demand. The mutant mitochondrial DNA level in blood cells therefore also does not necessarily reflect how sick the patient is. My question is whether other tissues could serve as a better starting material to increase our confidence in predicting the cross-generation transmission of mtDNA mutant, and also predicting the severeness of the symptoms in children? 

“Well, I am not an expert on mtDNA transmission in humans. One thing is for sure: it is a process with many complications. The differences in the nuclear genome also can have a big impact on how likely a mutant mtDNA will be transmitted and the disease penetrance in children who carry these mutants. Trying to predict how likely it is that a mother with a certain level of mtDNA mutant will have babies with below a certain percentage of mutant genome might give patients some guidance, although it is hard to tell how reliable, accurate and valuable (i.e. useful) the predictions will be for each patient.”

Sarah Norcross, Director of the Progress Educational Trust, said:

“It is promising to see progress being made in identifying which women could benefit from mitochondrial donation. It is important to remember that mitochondrial donation is, at present, only appropriate for one specific and vital purpose – avoiding mother-to-child transmission of inherited mitochondrial disease. Mitochondrial donation is not permitted in the UK as a way of addressing infertility, (despite this having been attempted overseas), as there is not yet any persuasive evidence that it has merit as a means of treating fertility problems.”

‘Mitochondrial Donation — Which Women Could Benefit?’ by Pickett et al. was published in NEJM at 22:00 UK time on Wednesday 15^th May 2019.

Declared interests

Sarah Norcross: “PET does not have any relevant interests.”

Dr Hansong Ma: “No conflicts of interest to declare.”