On the possibility of mosaic embryos transfer in the programmes of assisted reproductive technologies

Chromosomal mosaicism is a common finding in human embryos.

Objective: To determine the possibility of mosaic embryos transfer in the absence of euploid embryos and the importance of medical genetic counseling.

Materials and methods: 15 women with no prospects for obtaining euploid embryos were examined in the Academician V.I. Kulakov National Medical Research Center for Obstetrics, Gynecology and Perinatology, Ministry of Health of Russia during the period of 2022–2024. Preimplantation genetic testing (PGT) of all embryos was performed by high-performance next-generation sequencing on the Illumina platform (AneuPGT). Confirmatory prenatal diagnostics in 5 (33.3%) cases was performed in amniotic fluid by chromosomal microarray analysis and in one case a FISH method was additionally used.

Results: The following chromosomes were involved in mosaicism: 2, 5, 7, 8, 9, 10, 11, 14, 15, 16, 19, 20, 22, Y. Among the 16 (two mosaic embryos were transferred in one case) analyzed embryos, 10 (62.5%) had numerical mosaicism and in 6 (37.5%) embryos segmental mosaicism was found. Successful implantation occurred in 10 cases (with 5 cases of segmental mosaicism and 5 cases of numerical mosaicism), in one case a 9-week non-developing pregnancy took place, in 4 cases pregnancy did not occur. Afterwards 10 clinically healthy children were born.

Conclusion: Selection and transfer of mosaic embryos is possible and indicated for spouses with a burdened medical history and reduced reproductive potential according to medical genetic counseling, which allows the couple to give birth to a healthy child in the absence of euploid embryos.