Nuclear transfer to prevent mitochondrial DNA disorders: revisiting the debate on reproductive cloning

Preclinical experiments are currently performed to examine the feasibility of several types of nuclear transfer to prevent mitochondrial DNA (mtDNA) disorders. Whereas the two most promising types of nuclear transfer to prevent mtDNA disorders, spindle transfer and pronuclear transfer, do not amount to reproductive cloning, one theoretical variant, blastomere transfer does. This seems the most challenging both technically and ethically. It is prohibited by many jurisdictions and also the scientific community seems to avoid it. Nevertheless, this paper examines the moral acceptability of blastomere transfer as a method to prevent mtDNA disorders. The reason for doing so is that most objections against reproductive cloning refer to reproductive adult cloning, while blastomere transfer would amount to reproductive embryo cloning. After clarifying this conceptual difference, this paper examines whether the main non-safety objections brought forward against reproductive cloning also apply in the context of blastomere transfer. The conclusion is that if this variant were to become safe and effective, dismissing it because it would involve reproductive cloning is unjustified. Nevertheless, as it may lead to more complex ethical appraisals than the other variants, researchers should initially focus on the development of the other types of nuclear transfer to prevent mtDNA disorders.Mitochondrial DNA (mtDNA) disorders are usually severe disorders. Patients show a wide variety of symptoms, including deafness, blindness, diabetes, loss of skills and heart and liver failure. As there is no curative treatment, helping carriers of mtDNA mutations to have healthy children has been a central focus of attention. One reproductive option currently in development is nuclear transfer, in which faulty mitochondria are replaced with healthy ones. This should result in healthy offspring with the nuclear genes of the parents, but without the mtDNA mutation. Whereas the two most promising types of nuclear transfer to prevent mtDNA disorders do not amount to reproductive cloning, one theoretical variant would. This type seems the most challenging variant both technically and ethically. Most objections against reproductive cloning refer to reproductive adult cloning, while this variant would amount to reproductive embryo cloning. In this paper, we examine the moral acceptability of this variant as a method to prevent mtDNA disorders and whether and to what extent the main non-safety objections brought forward against reproductive cloning also apply against this variant of nuclear transfer to prevent mtDNA disease. The conclusion is that if this variant of nuclear transfer were to become safe and effective, dismissing it because it would involve reproductive cloning is unjustified. Nevertheless, as it may in practice lead to more complex ethical appraisals than the other variants, researchers should at least initially focus on the further development of the other types of nuclear transfer to prevent mtDNA disorders.