P–526 Incidence of mosaic embryos in day–6 blastocysts, may late blastulation predispose to mosaicism?

Autor: Murat Cetinkaya, Mehmet Ali Tufekci, Semra Kahraman, C Cina. Yapan
Rok vydání: 2021
Předmět:
Zdroj: Human Reproduction. 36
ISSN: 1460-2350
0268-1161
DOI: 10.1093/humrep/deab130.525
Popis: Study question May the mosaicism ratio be influenced by the time of blastulation in preimplantation genetic testing for aneuploidies (PGT-A)? Summary answer The mosaicism ratio is significantly higher in day–6 blastocysts when compared to day–5 when transferable embryos are considered only (euploids and mosaics). What is known already Conventionally, PGT-A has classified preimplantation embryos as either euploid or aneuploid. Yet, a major improvement in PGT-A methodology, with the introduction of high sensitivity diagnostic Next Generation Sequencing (NGS) technology, has allowed the identification of a third embryo category: the mosaic (Coll et al., 2021). Embryonic mosaicism can be defined as the presence of karyotypically distinct cell lines within an embryo and can be detected by NGS at a rate between 20–80%. In the absence of euploid embryos, mosaic embryos, when transferred, have been shown to deliver healthy live births (PGDIS, 2019). Study design, size, duration This retrospective study was based on 9828 trophectoderm biopsies performed in a single ART clinic between January 2017 and October 2020 for PGT-A cycles with more than one blastocyst. PGT-A cycles with only one blastocyst were excluded because in these cycles’ day–5/day–6 biopsy percentage cannot be calculated. A total number of 8398 and 1430 blastocysts were biopsied on day–5 and day–6, respectively for PGT-A by ReproSeq on Ion Torrent S5 (Thermo Fisher Scientific). Participants/materials, setting, methods Three categories were defined in the PGT-A group with >1 blastocyst biopsied to compare the rate of mosaicism: C1:cycles in which blastocysts were only biopsied on day–5 (n = 1872), C2:99–60% of blastocysts were biopsied on day–5 (n = 483) and C3:0–60% of blastocysts biopsied on day–5 (n = 411). The mean female age (C1:36.0±5.2; C2:35.7±4.8; C3:37.1±4.9) and metaphase II oocytes punctured (C1:9.8±6.5; C2:10.4±5.2; C3:8.4±5.4) were similar and statistically non-significant in all groups. T-test and Chi-square tests were used where appropriate. Main results and the role of chance Overall, from the blastocysts biopsied on day–5 and 6, 35.4% and 25.5% were euploid, 13.7% and 14.7% were mosaic, 50.9% and 59.8% were aneuploid, respectively (p Limitations, reasons for caution This study focused on blastocyst formation day and morphological blastocyst grading. Extrinsic factors have also been reported to induce mosaicism: ovarian stimulation, culture media, laboratory and culture conditions, technical issues during the biopsy and sample processing (Munné and Wells, 2017; Katz-Jaffe et al., 2018, Fragouli et al., 2010, 2019). Wider implications of the findings: Mitotic errors during cleavage stage causing mosaicism may lead to lower morphological grade and late blastulation as some cells in those embryos are not diploid thus leading to higher mosaicism for blastocysts that reach blastulation on day6 and/or yield only good-quality embryos. Trial registration number Not applicable
Databáze: OpenAIRE
Externí odkaz: