Proof of safety needed for mitochondrial disease treatments

20 April 2011

The Human Fertilisation and Embryology Authority (HFEA) has said that further experiments are required to demonstrate the safety of new techniques to prevent mitochondrial diseases by so-called ‘three parent IVF’.
Responding to a government request for expert opinion (see previous news), the HFEA panel examined three different methods. They concluded that the legal technique of pre-implantation genetic diagnosis (PGD) is ‘suitable for some, but not all, patients who suffer from mutations in their mitochondrial DNA’ and can only reduce (as opposed to prevent) the risk of transmission.
The other two techniques, maternal spindle transfer and pronuclear transfer – which are not currently legal - were found to be ‘potentially useful for a specific and defined group of patients whose offspring may have severe or lethal genetic disease, and who have no other option of having their own genetic child’. However, the panel adopted a cautious view, suggesting that further research is required into the safety of the techniques.
They propose a series of specific experiments as necessary to demonstrate a satisfactory level of safety, whilst bearing in mind that the move from research to clinical practice ‘always involves a degree of uncertainty’. These essential experiments are to check that human embryos develop normally following use of the techniques, and that baby primates produced using the technique (the closest animal proxy for humans) appear normal. Additional, desirable experiments are also proposed.
Comment: Although the experts express optimism that the techniques will indeed prove useful in preventing severe mitochondrial disease, they have taken a prudent approach in calling for more evidence before trials in humans should proceed.

Proponents of the techniques have called for the government to begin timetabling and preparing the legislative changes that would be required to make such trials legal, to speed up the anticipated clinical trials. This has some merit, but there is still the possibility that evidence of safety is not as easy to obtain as hoped; indeed, whilst unlikely, it may be that the current techniques are not safe enough. Perhaps a compromise would be suitable, where plans for legislative change follow closely, but do not anticipate, experimental schedules and outcomes. 

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