Offspring born of this technique are referred to as “three parent babies” which I think is unfortunate because for one thing it’s not strictly true from a genetic standpoint and for another I suspect it has contributed to some of the unnecessary moral panic that surrounds it.
Much of the objection to legalising this form of IVF has come (predictably) from the Church with both Catholics and Anglicans claiming scientific uncertainty as their rational but in fact the technique has been well tested and the people who actually understand the science are satisfied of its safety, with the usual caveats. Given the Vatican’s antipathy to any artificial fertilisation techniques I suspect their objections are entirely ideological and can therefore be ignored. For example Bishop John Keenan, the Bishop of Paisley, was among the Catholic leaders who condemned the technique claiming it “seeks to remove anyone affected by certain conditions from the human gene pool”. Of course what it actually does is remove the condition from the gene pool, the “anyone” in the above nonsense never existed except in the abstract.
Other objections seem more reasonable, for example the concern that the mitochondria continue into subsequent generations, but are grounded in a misunderstanding of mitochondria and their origins as the “powerhouse of the cell”. The “three parent” moniker is inappropriate because although the mitochondria contain DNA it is their DNA and does not contribute to human characteristics outside of the somatic effect of its function. The entire nuclear DNA in this technique, the stuff that can be considered to count, is derived from the natural parents and not from the donor of the egg. Ethically this is more akin to a transplant than genetic engineering.
Another point that has been missing from the public debate is that mitochondrial DNA is not really ‘human’ at all because these organelles are endosymbionts, remnants of previously free-living proteobacteria that either infected or were absorbed by other primitive cells over 1.5 Billion years ago. Over evolutionary time the mitochondria lost the genes necessary for autonomy and retained just enough for their own reproduction and metabolic function within their hosts. The gestalt of these two primitive cells formed the first truly eukaryotic cells that are the basis of all complex life.
I’m not convinced that any ethical Rubicon has been crossed by approving this technique. In fact, even if at some future date it is discovered that by some genetic tinkering in the nuclei of eggs destined for IVF we could eliminate cystic fibrosis or some other debilitating genetic condition we should do it. I do not subscribe to the sort of genetic essentialism that some, including rather bizarrely the church, seem to indulge in and although I’m prepared to accept that somewhere amongst all possible applications of human genetic engineering there will be some ethical red lines we’re nowhere close when it is used solely for the elimination of heritable diseases.