Preimplantation Genetic Testing (PGT)

Preimplantation genetic testing (PGT) comprises a set of molecular biological methods that allow assessment of the genetic status of an embryo prior to its implantation into the uterus (embryo transfer). The primary benefit of PGT is a reduced risk of transferring an embryo with a genetic abnormality. This helps prospective parents avoid difficult decisions and psychological stress associated with the possibility of pregnancy termination, which may negatively affect a woman’s health and her future ability to conceive.

PGT also contributes to a reduction in the number of embryo transfers and shortens the time required to achieve a healthy pregnancy. Our IVF center was among the first to introduce blastocyst-stage biopsy (day 5–6 of embryo development) for PGT. We therefore have many years of experience, which is crucial for maintaining embryo viability.

The main advantages of testing embryos at the blastocyst stage include minimal embryo damage during biopsy and higher diagnostic accuracy. Only embryos that develop properly are tested, and the ability to biopsy multiple cells further increases the precision of the analysis.Depending on the type of genetic abnormality being investigated, PGT is divided into PGT-A, PGT-SR, and PGT-M.

PGT-A, formerly known as preimplantation genetic screening (PGS), is performed during IVF and enables the selection of an embryo with a normal number of chromosomes for uterine transfer.

At Sanatorium Helios, this examination is performed using Next Generation Sequencing (NGS) technology.

Chromosomal aneuploidies in embryos may result in developmental arrest at various stages, failure of implantation, the need for pregnancy termination, or the birth of a child affected by conditions such as Down syndrome. The aim of PGT-A is therefore to increase IVF success rates and improve the likelihood of delivering a healthy child.

Our long-term experience shows that preimplantation genetic testing techniques increase live birth rates by more than 30%. For this reason, we recommend this examination to all couples undergoing IVF treatment.

PGT-SR (formerly also classified under PGS) is indicated when one or both partners are carriers of a balanced chromosomal translocation or another structural chromosomal rearrangement. Currently, we analyze structural rearrangements as well as aneuploidies using NGS technology.

PGT-M (formerly preimplantation genetic diagnosis – PGD) is intended for couples with a known risk of transmitting a serious genetic disorder caused by a mutation in a single gene. The most common conditions in our population include those screened during predictive genetic testing (GEN-TEST 1).

Couples may learn about their genetic risk through predictive testing; however, we are more often contacted by couples who have already had a child (frequently one who sadly passed away) diagnosed with a severe inherited disease.

In the past, such couples were faced with the choice of either remaining childless or risking disease transmission and potentially undergoing prenatal diagnosis followed by pregnancy termination.

Thanks to PGT-M, these couples now have the opportunity to have healthy children. By biopsying cells from embryos and performing PGT-M analysis, we are able to determine whether an embryo is genetically healthy, a carrier, or affected by a mutation associated with the future development of a specific monogenic disease.

The principle of PGT-M is based on direct and indirect DNA diagnostic methods using polymerase chain reaction (PCR).

Information regarding health insurance coverage of PGT-A/SR and PGT-M examinations (formerly PGS and PGD) will be provided by our IVF physicians and coordinators.

*Adapted from: Recommended Procedure No. 4 – Guidelines for Preimplantation Genetic Laboratory Testing, 2017, Czech Society for Medical Genetics (SLG).