Non-invasive chromosome screening for embryo preimplantation using cell-free DNA

Abstract

Preimplantation genetic testing (PGT) is a widely adopted screening method that can be performed to identify and select embryos with normal ploidy; however, PGT relies on embryo biopsy, that is, polar body, embryo cells, or trophectoderm biopsy, to obtain embryonic DNA, increase its technical limitations. Studies have indicated that biopsy may have an influence on the quality and development of embryos, and increase the chance of abnormal epigenetic modifications. Therefore, non-invasive PGT (niPGT) detection of cell-free DNA (cfDNA) has gradually become a hot research topic in the field of assisted reproduction. Studies showed cfDNA could be detected in blastocyst fluid and spent culture medium (SCM) in vitro cultured embryos. The cfDNA collection requires less skill and makes lower risk to embryos. Some studies have been conducted to evaluate the feasibility of SCM-based niPGT approaches. When comparing the ploidy consistency of cfDNA in SCM, its consistency to the conventional PGT for aneuploidies results fluctuated widely, it is critical to recognize the factors influencing accuracy. These contradictory results may be related to factors such as the difference in SCM sampling methods and sampling time, and the definition of consistency. In this review, we aimed to comprehensively summarize how researchers use embryonic cfDNA to conduct niPGT detection. It also systematically reviews the factors affecting the accuracy of the test and its underlying issues, as well as prospective applications. We hope to provide a basis for future niPGT research and a useful reference for the standardized operation of niPGT that can be widely applied in clinical practice.

Analyzing Cell-free Genomic DNA in Spent Culture Media: Noninvasive Insight into the Blastocysts

“…This provides further benefits to invasive PGT (iPGT), which relies heavily on embryo biopsy or blastocentesis. SCM-based PGT offers a viable option for assessing cultured embryos with diminished implantation potential, 26 which are not suitable for iPGT. SCM-PGT features a rapid turnaround time (less than 12 h from SCM collection to genetic analysis), potentially providing results before embryo transfer or cryopreservation.…”

A review of pre-implantation genetic testing technologies and applications

“…Although a few groups have reached ploidy concordances between BF samples and TE biopsy higher than 97%, the non-invasive method remains inferior to gold standard TE biopsy [110] . In addition, the amount of cfDNA in BF is relatively small, leading to false positive or false negative occurrences due to the uneven distribution of WGA and ADO [111] .…”

Clinical outcomes of single blastocyst transfer with machine learning guided noninvasive chromosome screening grading system in infertile patients

“…Preimplantation genetic testing for aneuploidy (PGT-A) is a clinically used genetic screening test for chromosomal ploidy of embryos, which can select normal blastocysts for transfer, thereby decreasing the miscarriage rate of patients, increasing the live birth rate, and shortening the time to achieve pregnancy [ 1 , 2 ]. However, PGT-A relies on invasive trophectoderm biopsy, which may affect embryo implantation, development, and even pose a risk to the long-term safety of the offspring [ 3 – 5 ]. In addition, PGT-A reports copy number variations (CNVs) in terms of euploidy and aneuploidy, with euploid embryos being selected for transfer, mosaic and aneuploid embryos being not selected for transfer.…”