It has been a long-standing rule in fertility treatment that no scientist should attempt to modify the genes of a human embryo if that modification can be passed on to subsequent generations through the “germline” – the eggs and sperm of the future person.
Germline gene therapy has been taboo for one very good reason. We cannot at present know with any certainty whether the technique is safe – not just for the baby, but to the children and grandchildren of that child. This is why the Human Fertilisation and Embryology Act has specifically outlawed any attempt at altering the genes of sperm, eggs or IVF embryos.
Now Parliament is about to consider another form of germline modification, so-called “three-parent embryos”, this time involving the genes of the mitochondria, described as the tiny “power packs” of the cell, which exist outside the nucleus. Unlike the chromosomes of the nucleus, where 99.9 per cent of human DNA is stored, mitochondrial DNA is passed on solely down the maternal line. Just like nuclear DNA, the DNA of the mitochondria can go awry and cause devastating mitochondrial diseases, the most severe of which affect about one in every 6,500 babies. The IVF technique of mitochondrial transfer could therefore offer hope to couples anxious to have IVF babies who are free of these terrible disorders.
But how do we know it is safe? Newcastle University researchers believe they now have evidence to suggest it is as safe as any new IVF technique can be. Unfortunately, this evidence cannot be released until it is formally published in a peer-reviewed journal, which could prove to be a problem for some MPs who would like to know more about the safety of this technique before casting their vote.
It is unfortunate that attempts to test the safety of the Newcastle technique in a primate animal have failed, raising questions about whether laboratory cells can tell us enough about the risks to future generations. MPs may be tempted to vote against the move to make the procedure legal because of this lack of safety evidence, but this would be a mistake. It is up to the Human Fertilisation and Embryology Authority, the fertility regulator, to assess safety. We must trust it with the heavy responsibility of this task.Reuse content