Preimplantation genetic testing: current challenges and future prospects.

INTRODUCTION: Preimplantation genetic testing (PGT) is now a widely applied procedure in genetic practices and ART, with more than one third of ART Centers in US already utilizing PGT technology. Its indications have also been significantly extended to include common late-onset disorders and non-genetic conditions, such as testing for HLA match. Areas covered: This is a critical review of the developments in PGT, with emphasis on their outstanding limitations and directions for the future research and practice in the area of PGT. Expert commentary: The application of the new higher resolution PGT technologies has led to the identification of genetic variations, the biological and clinical importance of which is not sufficiently understood. It is obvious that the current selection process of embryos with the highest developmental potential requires a further improvement, as significant proportion of transferred euploid embryos still fail to result in an ongoing clinical pregnancy. More research will be needed to upgrade PGT for different conditions into a single universal test in the same biopsy material. To avoid a potential damage of embryo biopsy procedures, one of the important challenges will be the development of non-invasive approaches to PGT.