According to Joanna Poulton, an expert in mitochondrial research at Oxford University, it is not yet appropriate to offer treatment with so little knowledge of the potential consequences when reasonable alternatives – such as egg donation from a woman unaffected by mitochondrial disease or pre-implantation genetic diagnosis – are available. She says, “There are very few families who don’t want to use donated oocytes (eggs), where PGD would not work, and where the risk of having severely affected babies is so high that it might be worth trying the new techniques.”