Transmission Of Mitochondrial DNA Disease Research Articles

Mitochondrial Replacement Therapy: In Whose Interests?

Mitochondrial replacement therapy (MRT), also called nuclear genome transfer and mitochondrial donation, is a new technique that can be used to prevent the transmission of mitochondrial DNA diseases. Apart from the United Kingdom, the first country to approve MRT in 2015, Australia became the second country with a clear regulatory path for the clinical applications of this technique in 2021. The rapidly evolving clinical landscape of MRT makes the elaboration and evaluation of the responsible use of this technology a pressing matter. As jurisdictions with less strict or non-existent reproductive laws are continuing to use MRT in the clinical context, the need to address the underlying ethical issues surrounding MRT's clinical translation is fundamental.

Mitochondrial Replacement Techniques, Scientific Tourism, and the Global Politics of Science.

The United Kingdom is the first and so far only country to pass explicit legislation allowing for the licensed use of the new reproductive technology known as mitochondrial replacement therapy. The techniques used in this technology may prevent the transmission of mitochondrial DNA diseases, but they are controversial because they involve the manipulation of oocytes or embryos and the transfer of genetic material. Some commentators have even suggested that MRT constitutes germline genome modification. All eyes were on the United Kingdom as the most likely location for the first MRT birth, so it was a shock when, on September 27, 2016, an announcement went out that the first baby to result from use of the intervention had already been born. In New York City, United States‐based scientist John Zhang used maternal spindle transfer (one of the recognized MRT methods) to generate five embryos for a woman carrying oocytes with deleterious mutations of the mitochondrial DNA. Zhang then shipped the only euploid embryo to Mexico, where it was transferred to the mother's uterus. Zhang's team's travel across international borders to carry out experimental procedures represents a form of scientific tourism that has not been properly ethically explored; it can, however, have seriously detrimental effects for developing countries.

Can reproductive technologies prevent transmission of mitochondrial DNA disease?

Can reproductive technologies prevent transmission of mitochondrial DNA disease?

Concise reviews: Assisted reproductive technologies to prevent transmission of mitochondrial DNA disease.

While the fertilized egg inherits its nuclear DNA from both parents, the mitochondrial DNA is strictly maternally inherited. Cells contain multiple copies of mtDNA, each of which encodes 37 genes, which are essential for energy production by oxidative phosphorylation. Mutations can be present in all, or only in some copies of mtDNA. If present above a certain threshold, pathogenic mtDNA mutations can cause a range of debilitating and fatal diseases. Here, we provide an update of currently available options and new techniques under development to reduce the risk of transmitting mtDNA disease from mother to child. Preimplantation genetic diagnosis (PGD), a commonly used technique to detect mutations in nuclear DNA, is currently being offered to determine the mutation load of embryos produced by women who carry mtDNA mutations. The available evidence indicates that cells removed from an eight-cell embryo are predictive of the mutation load in the entire embryo, indicating that PGD provides an effective risk reduction strategy for women who produce embryos with low mutation loads. For those who do not, research is now focused on meiotic nuclear transplantation techniques to uncouple the inheritance of nuclear and mtDNA. These approaches include transplantation of any one of the products or female meiosis (meiosis II spindle, or either of the polar bodies) between oocytes, or the transplantation of pronuclei between fertilized eggs. In all cases, the transferred genetic material arises from a normal meiosis and should therefore, not be confused with cloning. The scientific progress and associated regulatory issues are discussed. Stem Cells 2015;33:639–645

The challenges of mitochondrial replacement.

The challenges of mitochondrial replacement.

Current Methods for the Prevention of Transmission of Mitochondrial DNA Diseases

It is estimated that mitochondrial diseases affect 1 in 5,000-10,000 live births. At present, there is no cure for a mitochondrial disease and current treatments are limited to reducing symptoms and slowing disease progression. The prevention of transmission of mitochondrial diseases is of vital importance to parents with a mitochondrial disease who wish to make informed reproductive decisions. This paper provides a critical evaluation of the various established and experimental techniques involved in the prevention and treatment of mtDNA disease at the germline level, including fertilization using donor oocytes, pre-implantation genetic diagnosis, chorionic villus sampling, amniocentesis, cytoplasmic transfer, germinal vesicle transfer, pronuclear transfer, and spindle-chromosomal complex transfer; the latter two of which have been publicly endorsed by the Human Fertilisation and Embryology Authority in the UK in 2014 as being potentially useful and safe methods for the prevention of transmission of severe mtDNA diseases.

P57 Development of the Pronuclear Transfer Technique to Prevent Transmission of Mitochondrial DNA Disease in Humans

P57 Development of the Pronuclear Transfer Technique to Prevent Transmission of Mitochondrial DNA Disease in Humans

Mitochondrial DNA disease: new options for prevention

Very recently, two papers have presented intriguing data suggesting that prevention of transmission of human mitochondrial DNA (mtDNA) disease is possible. [Craven, L., Tuppen, H.A., Greggains, G.D., Harbottle, S.J., Murphy, J.L., Cree, L.M., Murdoch, A.P., Chinnery, P.F., Taylor, R.W., Lightowlers, R.N. et al. (2010) Pronuclear transfer in human embryos to prevent transmission of mitochondrial DNA disease. Nature, 465, 82-85. Tachibana, M., Sparman, M., Sritanaudomchai, H., Ma, H., Clepper, L., Woodward, J., Li, Y., Ramsey, C., Kolotushkina, O. and Mitalipov, S. (2009) Mitochondrial gene replacement in primate offspring and embryonic stem cells. Nature, 461, 367-372.] These recent advances raise hopes for families with mtDNA disease; however, the successful translational of these techniques to clinical practice will require further research to test for safety and to maximize efficacy. Furthermore, in the UK, amendment to the current legislation will be required. Here, we discuss the clinical and scientific background, studies we believe are important to establish safety and efficacy of the techniques and some of the potential concerns about the use of these approaches.

Transmission of Mitochondrial DNA Diseases and Ways to Prevent Them

Recent reports of strong selection of mitochondrial DNA (mtDNA) during transmission in animal models of mtDNA disease, and of nuclear transfer in both animal models and humans, have important scientific implications. These are directly applicable to the genetic management of mtDNA disease. The risk that a mitochondrial disorder will be transmitted is difficult to estimate due to heteroplasmy—the existence of normal and mutant mtDNA in the same individual, tissue, or cell. In addition, the mtDNA bottleneck during oogenesis frequently results in dramatic and unpredictable inter-generational fluctuations in the proportions of mutant and wild-type mtDNA. Pre-implantation genetic diagnosis (PGD) for mtDNA disease enables embryos produced by in vitro fertilization (IVF) to be screened for mtDNA mutations. Embryos determined to be at low risk (i.e., those having low mutant mtDNA load) can be preferentially transferred to the uterus with the aim of initiating unaffected pregnancies. New evidence that some types of deleterious mtDNA mutations are eliminated within a few generations suggests that women undergoing PGD have a reasonable chance of generating embryos with a lower mutant load than their own. While nuclear transfer may become an alternative approach in future, there might be more difficulties, ethical as well as technical. This Review outlines the implications of recent advances for genetic management of these potentially devastating disorders.

Pronuclear transfer in human embryos to prevent transmission of mitochondrial DNA disease

Mitochondrial DNA (mtDNA) mutations are a common cause of genetic disease with pathogenic mtDNA mutations being detected in approximately 1 in 250 live births1-3 and at least 1 in 10,000 adults in the UK affected by mtDNA disease4. Treatment options for patients with mtDNA disease are extremely limited and are predominantly supportive in nature. MtDNA is transmitted maternally and it has been proposed that nuclear transfer techniques may be an approach to prevent the transmission of human mtDNA disease5,6. Here we show that transfer of pronuclei between abnormally fertilised human zygotes results in minimal carry-over of donor zygote mtDNA and is compatible with onward development to the blastocyst stage in vitro. By optimising the procedure we found the average level of carry-over following transfer of two pronuclei is <2.0%, with many of the embryos containing no detectable donor mtDNA. We believe that pronuclear transfer between zygotes, as well as the recently described metaphase II spindle transfer, has potential to prevent the transmission of mtDNA disease in humans.

The battle to prevent the transmission of mitochondrial DNA disease: Is karyoplast transfer the answer?

The battle to prevent the transmission of mitochondrial DNA disease: Is karyoplast transfer the answer?