Relationship between age and blastocyst chromosomal ploidy analyzed by noninvasive preimplantation genetic testing for aneuploidies (niPGT-A)

An Update on Non-invasive Approaches for Genetic Testing of the Preimplantation Embryo

Preimplantation Genetic Testing (PGT) aims to reduce the chance of an affected pregnancy or improve success in an assisted reproduction cycle. Since the first established pregnancies in 1990, methodological approaches have greatly evolved, combined with significant advances in the embryological laboratory. The application of preimplantation testing has expanded, while the accuracy and reliability of monogenic and chromosomal analysis have improved. The procedure traditionally employs an invasive approach to assess the nucleic acid content of embryos. All biopsy procedures require high technical skill, and costly equipment, and may impact both the accuracy of genetic testing and embryo viability. To overcome these limitations, many researchers have focused on the analysis of cell-free DNA (cfDNA) at the preimplantation stage, sampled either from the blastocoel or embryo culture media, to determine the genetic status of the embryo non-invasively. Studies have assessed the origin of cfDNA and its application in non-invasive testing for monogenic disease and chromosomal aneuploidies. Herein, we discuss the state-of-the-art for modern non-invasive embryonic genetic material assessment in the context of PGT. The results are difficult to integrate due to numerous methodological differences between the studies, while further work is required to assess the suitability of cfDNA analysis for clinical application.

Noninvasive preimplantation genetic testing for aneuploidies (niPGT-A) and the principle of primum non nocere

Perhaps with the intention of obtaining larger amounts of free-DNA, some groups are routinely postponing and establishing free-DNA collection in culture medium for Noninvasive preimplantation genetic testing for aneuploidies (niPGT-A) to day 6 for all blastocysts. A meta-analysis served as the basis for such decision, since statistically similar live birth rates were observed when the transfers of euploid blastocysts were performed on day 5 versus day 6 However, the euploidy analysis was conducted in only two studies However, after including the two more studies we performed a new meta-analysis that clearly showed the risks of losing live births with the decision of adopting the 6th day as the endpoint for gathering free-DNA. We would be losing 1.71x more live births.