Validation of simultaneous preimplantation genetic testing (PGT) for aneuploidy, monogenic, and polygenic disorders

Preimplantation genetic testing in assisted reproduction technology

A significant proportion of clinically recognized pregnancies end in miscarriage. About 50 % of early pregnancy losses are due to chromosome abnormalities. In assisted reproduction technology (ART), a high proportion of top-quality embryos with morphological values are aneuploid whenever they have been evaluated in terms of genetic integrity in human preimplantation embryos either from in vitro or in vivo matured oocytes. It is plausible to think of preimplantation genetic testing (PGT) as a means of increasing pregnancy rates and minimizing the risk of fetal aneuploidy. It is believed that PGT will assume a prominent role in the field of ART, especially in a successful pregnancy, so it is embraced recently as a popular diagnostic technique. The PGT includes three sub-categories of PGT for aneuploidies (PGT-A), PGT for single gene / monogenic disorders (PGT-M), and PGT for chromosome structural rearrangements (PGT-SR). PGT-A is used to detect aneuploidies and previously it was known as PGS. PGT-M, formerly known as PGD, is intended to reduce monogenic defects. Previously known as PGS translocation, PGT-SR is PGT to identify structural chromosomal rearrangements. Since many of the old and new definitions for PGT are still vague and confusing for some researchers in the field of reproductive genetics, the main purpose of this study is to introduce all PGT classifications as well as elaborate on different aspects of this technology to improve ART outcomes.

Past, Present, and Future Strategies for Enhanced Assessment of Embryo's Genome and Reproductive Competence in Women of Advanced Reproductive Age

Recent advancements in genomic analysis allow testing of an increasing number of genetic features in human preimplantation embryos. Typical single gene mutation and whole chromosomes testing can now be integrated with assessment of mitochondrial DNA and polygenic conditions. Diagnostic expansion into epigenetic and transcriptomic assessment in the near future are potential technological targets which may improve the prognostic outlook of patients of advanced reproductive age and overall in vitro fertilization (IVF) treatment outcomes. In this review, we discuss the technological progress of recent years and their future applications in preimplantation genetic testing in IVF.