The head of our molecular genetics laboratory, Mgr.Rostislav Navrátil, Ph.D. was spoke about at current trends in preimplantation genetic testing of embryosthe conference: VITA NOVA in Bratislava.
Since the 1990s, Preimplantation Genetic Testing for Aneuploidies (PGT-A) has enabled us to detect chromosomal abnormalities in embryos resulting from the IVF process and thus increase the success rate of treatment of fertility disorders and, at the same time, significantly reduce the risk of pregnancy complications. From the initial analyses of a few selected chromosomes using the FISH method in the blastomeres of a three-day-old embryo, we have gradually progressed to the routine testing of multi-cell biopsies of the trophectoderm and the analysis of all human chromosomes. Modern massively parallel sequencing techniques replaced the older aCGH method in the last decade, which allowed us to detect chromosome mosaicism much better. We discovered very early that this type of aberration could affected a relatively significant percentage of embryos. In recent years, more and more workplaces have been dealing with the clinical impact of mosaic embryo transfer, which has led to efforts to create comprehensive recommendations from professional societies. As it turns out, the correct reporting of these findings also plays a very significant role in the correct setting of laboratory procedures, evaluation software and other technical aspects. Incorrectly set criteria and procedures can result in false-negative and false-positive results, which ultimately significantly misrepresent the conclusions of clinical studies after the transfer of mosaic embryos, to which the recommendations often apply.
Today‘s trends in the field of PGT-A primarily include efforts to reduce the false positivity and negativity of mosaic findings and overcome some of the technical limitations that classical analysis approaches have. This is, for example, the ability of the method to detect polyploidy or haploidy in a biopsy sample. The challenge in the coming years is mainly the technical evolution of preimplantation genetic testing methods, which will allow us to estimate better the clinical potential of embryos with certain types of chromosome aberrations, reduce the risk of unnecessary discarding of promising embryos and thus significantly increase the success rate of the entire IVF treatment.