PGT-A: Preimplantation genetic testing for aneuploidies
The PGT-A method is performed prior to embryo transfer, and it...
decreases the risk of spontaneous abortions, complications during pregnancy or the birth of an affected child
allows to select the embryo with the biggest potential for transfer and thus increase the success of infertility treatment
is recommended mainly for women of higher reproductive age (35+), or in case of repeated spontaneous abortions and repeated unsuccessful IVF treatments, in case of chromosomal aberrations in a fetus or a child and after an oncological treatment
is performed by collecting several cells from the developing embryo
What is PGT-A?
Preimplantation genetic testing for aneuploidies (PGT-A) is performed during IVF treatment and allows to select the embryo with the biggest potential for transfer and thus increase the success of infertility treatment. By transferring such embryo we achieve better implantation success, decrease the risk of a spontaneous abortion and pregnancy complications tremendously and increase the chance of having a healthy offspring.
Who is PGT-A suitable for?
The probability of developing aneuploidies is rising with increasing maternal age. That means the main reason for fertility issues are women over 35 years of age. This method is therefore especially suitable for all the couples of higher reproductive age, as well as those who overcame multiple spontaneous abortions. Furthermore, it is intended for patients with unsatisfactory spermiogram parameters, after childbirth or abortion of the fetus with a congenital defect and after oncological treatment using chemotherapy or radiation therapy.
How does it work?
PGT-A uses Massively Parallel Sequencing method (MPS). During sample preparation, DNA of embryos is multiplied several times and subsequently, DNA of all 23 human chromosome pairs are read. Information about the number of such sequence reads is then compared with the control sample, which has the right copy number of all chromosomes. This way we can reveal if some sequences are abundant or missing in embryo sample. Thus we detect numerical aberrations of all human chromosomes and choose euploid embryos with the highest implantation potential for transfer.
What are the benefits of PGT-A using MPS?
The main benefit of PGT-A using MPS is the ability to examine all human chromosomes at once. In contrast with Array Comparative Genome Hybridization (aCGH) method used in the past, MPS allows us to examine up to 96 embryos in one run. At the same time, thanks to much higher resolution, we can detect so-called segmental aneuploidies, where only part of the chromosome is abundant or missing in embryo cells. Moreover, a greater dynamic range of sequencing methods gives more precise information about chromosomal mosaicism - a situation where there are aneuploid cell lines along with the normal cells in a human embryo.