Preimplantation genetic testing for aneuploidies (PGT-A) of human blastocyst

The aim of preimplantation genetic testing (PGT) is to analyse the state of health of an embryo biopsied and screened considering the chromosomal set or known genetic mutations, before the transfer to the uterus. The couple requesting a PGT undergoes assisted reproductive techniques (ART) in order to produce embryos that are biopsied through an invasive procedure and then analysed for specific genetic diseases or chromosomal aberrations. Embryos affected by genetic diseases or chromosomal abnormalities are not selected for clinical use while the remaining, which are euploid, are potentially able to allow a pregnancy. PGT-A (preimplantation genetic testing for aneuploidies) is a test performed on embryos in order to detect numerical chromosomal abnormalities. According to different studies performed in IVF cycles, PGT-A reduces time to live birth, avoiding the transfer of abnormal embryos, according to maternal age. In fact, there has been a reduction of the time to live-birth when PGT-A was performed on blastocysts of women over 35 years- old-mark, underlining the importance of maternal age as an indication for PGT-A. Considering the availability of only one blastocyst for the transfer, PGT-A improves the implantation rate for embryo transfer and decreases total pregnancy loss, avoiding also the transfer of aneuploid embryos which can be ineffective and potentially risky. Although current methods have shown an improvement, there is still a debate regarding the effectiveness of this technique. Further studies are also investigating the possibility to perform a less invasive test, but, nowadays, PGT-A is considered a valid procedure in order to evaluate the health of the embryos and allow an improvement in IVF cycles by lowering miscarriage rates and selecting competent embryos for reproductive purposes.