Embryo Mosaicism Rate in National Referral Hospital of Indonesia Detected Using Next-Generation Sequencing: A Retrospective Study.

Background: Chromosomal mosaicism, a phenomenon observed in a minority of embryos, showcases its prevalence and inherent unpredictability, leading to variations in embryo mosaic rates across different centers. This research endeavors to assess the prevalence of mosaicism and its characteristics within the scope of our preimplantation genetic testing-A (PGT-A) services in Indonesia. Specifically focusing on our center's experience since 2020, this study aims to elucidate mosaic rates among embryos in our care.

Materials and methods: In a retrospective approach, we collected secondary data sourced from our PGT-A outcomes dating back to 2020. A total of 196 embryos underwent analysis, their characteristics were documented and presented descriptively. Notably, the incidence of specific chromosome abnormalities was outlined. We assess a comparative analysis to investigate the relationship between mosaicism and its corresponding clinical characteristics.

Results: In the analysis of 196 embryos, 106 (54.1%) displayed chromosomal anomalies spanning from low-level mosaicism to whole chromosome aneuploidy. Low mosaicism was observed in 25 (12.8%) of the embryos, while high mosaicism was identified in 8 (4.1%) embryos. Notably, low-level mosaicism predominated in chromosome 9 (n=10, 5.1%), whereas abnormality prevalence was highest in chromosome 21 (n=20, 10.2%). Statistical analysis revealed no significant disparity in mean maternal age among embryos with low-level mosaicism, high mosaicism, and normal chromosomes (33.88 vs. 35 vs. 33.26 years old, respectively). However, a statistically significant difference in mean maternal age (35.84 vs. 33.26 years) was observed between embryos with aneuploidy (monosomy or trisomy) and those with normal chromosomes. Furthermore, a significant difference in high mosaicism rates was detected in patients with unexplained infertility (P<0.05).

Conclusion: In contrast to the study conducted elsewhere, our center had a higher mosaicism rate. Chromosomes 9, 8, and 6 were the most frequently affected. There was a significant difference in the high mosaicism rate for PGT-Arelated unexplained infertility causes.