This webinar describes a study that used two independent next-generation sequencing (NGS) platforms to gain insight into the impact of different types of aneuploidies during preimplantation genetic testing.
Preimplantation genetic testing of aneuploidies (PGT-A) enables the selection of euploid embryos in order to increase implantation rates and reduce miscarriage rates after embryo transfer. NGS platforms provide high resolution and dynamic range for detection of sub-chromosomal segmental aneuploidies and mosaicism, but the impact of these findings remains unclear.
In this webinar, Jakub Horák of Repromeda, a center for reproductive medicine and preimplantation genetic diagnosis in the Czech Republic, describes a study that compared the reproducibility of different aneuploid findings in order to gain a better understanding of their impact.
The study included 95 embryos that previously analyzed at the blastocyst stage (day 5/6) by trophectoderm biopsy and the VeriSeq™ PGS Kit from Illumina. After blastocyst re-expansion, a second trophectoderm sample of the same size was biopsied for analysis using the PG-Seq™ platform from Perkin Elmer. While detection of whole chromosomal aneuploidy was highly concordant between two samples of the same embryo (97 percent), poor reproducibility (10 percent to 50 percent) was observed for segmentals and mosaics.
These results are consistent with the assumption that the vast majority of whole chromosomal aneuploidies originate in meiosis and affect the whole embryo. In contrast, segmentals and mosaics result from genetic instability in the first mitotic divisions during early embryo development and could possibly result in a healthy livebirth when chromosomally normal cell lines are present in the developing embryo.
Dr. Horák discusses the impact of these conclusions, including the fact that these findings should be reflected in PGT-A result reporting and patient counselling.