LAUSR

Introduction Mitochondrial pathology is characterized by maternal inheritance. Women may be hidden mutation carriers, but in some cases the risk for descendants may reach up to 100%. Due to the uneven distribution of mitochondria during cell division, the practice of preimplantation testing of embryos has significant limitations, and prenatal diagnosis may be unacceptable. The first baby after nuclear transfer procedures was born in 2016 (J. Zhang et al., 2017). Material and methods The study included a married couple with a confirmed hidden woman's carriage of Leigh syndrome mutation (37 years old). The couple had a history of birth of a girl with Leigh syndrome. For ethical reasons, prenatal diagnosis and donation of oocytes were not considered for further childbirth. The patient's mutation carrier status has been confirmed in independent laboratories (mtDNA 9176 T>C, Heteroplasmy ∼ 40%). The child was diagnosed with confirmed Leigh syndrome (Homoplasmy 99.4%). The couple had 2 controlled ovarian stimulations followed by nuclear transfer procedures. Embryo biopsy was performed on Days 5-6 of development. Preimplantation genetic embryo testing PGT-A (NGS: Veriseq, Illumina) and heteroplasmy testing of pathological mutation (NGS, coverage of >1000x) were performed. Rresults During the first stimulation, 3 blastocysts (euploid female embryo and two aneuploid embryos) were obtained. After consultation with the patients, it was decided not to use the female embryo for the embryo transfer. During the second stimulation, 6 blastocysts, incl. 3 aneuploid and 3 euploid (males) were obtained. Heteroplasmy of euploid embryos for pathological mutations: 0.51 ± 0.02%, 2.96 ± 0.05 and 3.32 ± 0.06%. The embryos obtained during ART from a patient with a mtDNA mutation carrier status were characterized by a low level of heteroplasmy of mtDNA mutation and had a low risk of mitochondrial pathology development. The patient is preparing for embryo transfer. Conclusions Nuclear transfer procedures showed high efficiency in describes case. But it is still experimental and highly controversial procedure. Further investigations and long term follow up of children is required.