Current experience concerning mosaic embryos diagnosed during preimplantation genetic screening

Area of Science:

• Reproductive genetics
• Embryology
• Genomic analysis

Background:

• Embryo mosaicism, the presence of multiple cell lines within an embryo, has been recognized for decades.
• Early detection methods like fluorescence in situ hybridization (FISH) had limitations in accurately assessing chromosomal copy numbers and were prone to bias.
• Recent advancements in molecular techniques have significantly improved the ability to analyze and understand mosaic embryos.

Purpose of the Study:

• To review current data on human embryo mosaicism.
• To discuss the clinical implications and future management of mosaic embryos.
• To explore interdisciplinary approaches from other genetics fields for better handling of mosaicism.

Main Methods:

• Review of recent molecular techniques for human embryo analysis.
• Analysis of data from preimplantation genetic screening.
• Comparative assessment of FISH versus newer molecular methods.

Main Results:

• Modern molecular techniques enable more accurate identification and characterization of mosaic embryos.
• Three distinct embryo classifications are now recognized post-preimplantation genetic screening: euploid, aneuploid, and mosaic aneuploid.
• Mosaic embryos can now be identified, transferred, and followed, leading to a better understanding of their developmental potential.

Conclusions:

• Advances in molecular diagnostics have transformed the understanding and management of embryo mosaicism.
• A clear classification system (euploid, aneuploid, mosaic aneuploid) is crucial for clinical decision-making.
• Collaborative efforts across genetics fields are essential for advancing the comprehensive management of mosaic embryos.