It is well established that human oocytes are extremely often aneuploid. It is the most common chromosome abnormality in humans and the leading genetic cause of miscarriages and congenital birth defects. It also lowers pregnancy rate and decreases the chance for conception. Initially it was thought that this issue affected only older women. However it has been shown that the frequency of aneuploidy, in cleavage stage embryos, can vary from 50 % in young women to even more than 80 % in women over the age of 42.
Nowadays, Preimplantation Genetic Screening (PGS) for aneuploidies is very powerful tool for embryo selection, allowing us to detect genetically abnormal embryos. Although, PGS performed with current methods (FISH, aCGH) was reported to improve pregnancy outcomes, more efficient tools were still needed. The ultimate goal is finding a non invasive procedure allowing sequencing of each embryo’s whole genome. A step forward is a routine clinical use of next generation sequencing (NGS) for biopsied embryos, which we present in our article. In this study we evaluated the effect of PGS-NGS on pregnancy and embryo implantation rate in women treated by means of long stimulation protocol in vitro fertilization (IVF) cycles.
Our study involved performing PGS-NGS on samples obtained from blastomere biopsy of cleavage stage embryos and transferring the embryos in fresh cycle. 45 patients were included in the group that underwent PGS-NGS, and 53 patients treated at the same time were selected to serve as a control group. All of them suffered from repeated implantation failures. They were selected according to age, cause of infertility, duration of infertility and AMH level. They did not differ in other hormonal parameters which we routinely verify.
Our result have shown a significant improvement in the treatment outcomes. The implantation rate was nearly 30 percentage points higher when PGS with NGS was performed (61.5 % vs. 34.8 %, p< 0.01). This is a proof for huge usefulness of NGS for infertility treatment purposes.
More detail description of this study as well as advantages of NGS over currently used PGS methods is available in our article :