Genetic analysis of biopsy-related droplets in patients undergoing PGT-A and its potential application

Preimplantation genetic testing for aneuploidy (PGT-A) is essential for selecting embryos free from chromosomal abnormalities before transfer. However, challenges such as detection failures, mosaicism, and the limited accuracy of trophectoderm biopsy in representing the full chromosomal status of the blastocyst persist. Therefore, additional genetic information is needed to complement traditional PGT methods. This study investigated whether biopsy-related droplets (BRDs) contain detectable genetic material and evaluated their characteristics and potential clinical applications.

A total of 318 BRDs were collected from 105 patients undergoing PGT-A. These droplets, generated during the biopsy process, underwent genomic DNA amplification and next-generation sequencing to detect copy number variations (CNVs).

The nucleic acid content of BRDs showed no significant correlation with blastocyst morphological grade, but was associated with the developmental day and chromosomal ploidy detected by PGT-A. BRDs of non-euploid blastocysts had higher nucleic acid content than those from euploid ones. Among 91 BRDs with successful CNV detection, 80.22% showed chromosomal ploidy results consistent with PGT-A. The clinical pregnancy rate for BRD-identified euploid blastocysts was significantly higher (84.62%) compared to those with failed or undetectable BRD results (58.00%). Notably, 8 of the 9 non-euploid blastocysts identified by BRD testing did not result in pregnancy. Furthermore, for 5 blastocysts that underwent secondary biopsy after initial PGT-A failure, chromosomal ploidy results from BRD analysis and secondary PGT-A were 80% consistent.

BRD-based genetic analysis may serve as an auxiliary tool to PGT, improving embryo selection and transfer decisions by providing additional chromosomal insights.