Analysis of Concordance of Pre-implantation Aneuploidy Genetic Testing Results Obtained Using Next Generation Sequencing on Illumina Platform in Cells of Various Parts of Trophoblast

Abstract

Study Objective: To study trophoblast (TB) cells taken from various sections of the embryo using Next Generation Sequencing (NGS) on Illumina platform, and to compare data in order to identify the degree of discordance between various samples from one embryo. Study Design: Comparative study. Materials and Methods. For the study, we used human embryos at early development stages, which originated from artificial insemination of germ cells taken from healthy donors with normal karyotype within the scope of the in vitro fertilisation program. We selected 14 human embryos originating from insemination of oocytes of 10 donors aged 20 to 32 years old with sperm taken from 9 donors from the semen bank of the International Centre for Reproductive Medicine. Two embryos underwent degradation during defrosting. For 12 embryos, we performed a repeated TB cells biopsy from two independent sections: one biopsy from TB adjacent to inner cell mass (ICM) cells and the other TB biopsy from blastocyte pole opposite to the embryoblast. Study Results. A comparison of molecular karyotype of TB cells taken from various sections of blastocyte in 12 embryos, 36 samples (3 sample for each embryo), demonstrated partial discordance only in one observation. In initial study, molecular karyotype of an embryo showed trisomy 16 syndrome: Seq(16)x3,(XY)x1. In the follow-up study, we found an additional deletion in the form of mosaicism in chromosome 7 section adjacent to ICM of the embryo: Seq(16)x3,(7q21.3 -> 7q36.3)x[0.5]). All other results demonstrated complete concordance irrespective of a TB section in question or a laboratory where sequencing was performed. Conclusion. It may be concluded that pre-implantation aneuploidy genetic testing of 5-day-old embryos using Next Generation Sequencing on Illumina platform allows obtaining reliable information on chromosomal abnormalities and can be successfully used to identify aneuploidy in pre-implantation embryos. Keywords: pre-implantation aneuploidy genetic testing, Next Generation Sequencing, in vitro fertilisation, aneuploidy, embryo mosaicism, chromosomal pathology.