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Mitochondrial DNA (mtDNA) mutations are maternally inherited and are associated with a broad range of debilitating and fatal diseases. Reproductive technologies designed to uncouple the inheritance of mtDNA from nuclear DNA may enable affected women to have a genetically related child with a greatly reduced risk of mtDNA disease. Here we report the first preclinical studies on pronuclear transplantation (PNT). Surprisingly, techniques used in proof-of-concept studies involving abnormally fertilized human zygotes were not well tolerated by normally fertilized zygotes. We have therefore developed an alternative approach based on transplanting pronuclei shortly after completion of meiosis rather than shortly before the first mitotic division. This promotes efficient development to the blastocyst stage with no detectable effect on aneuploidy or gene expression. After optimization, mtDNA carryover was reduced to <2% in the majority (79%) of PNT blastocysts. The importance of reducing carryover to the lowest possible levels is highlighted by a progressive increase in heteroplasmy in a stem cell line derived from a PNT blastocyst with 4% mtDNA carryover. We conclude that PNT has the potential to reduce the risk of mtDNA disease, but it may not guarantee prevention.

Original publication

DOI

10.1038/nature18303

Type

Journal article

Journal

Nature

Volume

534

Pages

383 - 386

Keywords

Adult, Blastocyst, Cell Nucleus, Cytoplasm, DNA, Mitochondrial, Female, Gene Expression Profiling, Humans, Male, Meiosis, Mitochondria, Mitochondrial Diseases, Mitochondrial Replacement Therapy, Nuclear Transfer Techniques, Stem Cells, Translational Medical Research, Young Adult, Zygote