Last February, the British Government approved “Three Parent IVF” (cf. Gènéthique du 4 février 2015). This technique involves creating embryos from 3 DNA (that of the father, the mother and an egg donor) to prevent the transmission of genetic diseases carried by the mother’s mitochondrial DNA. The defective mitochondria are removed from the mother’s egg and replaced by healthy mitochondria taken from the gametes of another woman. This “medical advance” has caused a stir amongst scientists specialising in reproduction and is continuing to fuel an on-going debate. An article published in the Nature journal this week unveiled “the hidden risks of three-parent babies”.
Research conducted in the 90s by French scientists showed that exchanging the mitochondria between mice altered their behaviour and brain anatomy. To date, mitochondria have not been perceived as having a biological effect. Following these discoveries, however, other scientists have found that not only do the mitochondria provide energy but they are also associated with neurological disorders, cancers and ageing. Thus, the mitochondria are no longer “insignificant” genomes.
The generalisation of “Three parent IVF” divides scientists. Many of them do not yet know how the baby’s genome will be modified or how it will develop over time. Further investigations would incorporate “planning for risks associated with family experiments”. However, others believe that legalising and generalising this approach “may be well worth it for women who want to avoid transmitting serious and rare disorders to their offspring”. As far as Doug Turnbull, Director of the Research Group at Newcastle University is concerned, “mitochondria are only donated to prevent any serious diseases linked with mitochondria from being transmitted. There is no reason to believe that this procedure would prove useful for anything else”.
However, scientists in both camps agree “that is no way of predicting with any certainty what will happen in the long term to children born following mitochondrial exchange”.
Nature (23/09/2015) Garry Hamilton