Preimplantation genetic screening of embryos (PGT-A, PGT-M)
An incorrect number of chromosomes in the embryo can be one of the many causes of unsuccessful IVF cycles. A condition in which the embryo has extra chromosomes or is missing some chromosomes is called aneuploidy. Preimplantation genetic testing (PGT-A), which is performed during IVF, makes it possible to select a viable embryo with a normal number of chromosomes. Chromosome aneuploidy screening of embryos prior to embryo transfer makes it possible to select only embryos without recognisable genetic abnormalities. The aim of this examination is to increase the chance of a healthy child and the success rate of the IVF cycle.
Experts recommend it not only to couples with genetic risks, but also to all other couples with:
- advanced age of the woman
- unexplained recurrent miscarriages
- chromosomal translocations
PGT-M ( Preimplantation Genetic Diagnosis) for rare diseases is intended for couples where there is a proven risk of passing on a serious genetic disease that is transmitted from parents to descendant through a single genetic defect.
Preimplantation genetic diagnosis is a method that enables the selection of a healthy, genetically unaffected embryo. This method is characterised by the fact that it is always combined with assisted reproduction methods and IVF and that the embryo is selected before it is transferred to the woman’s uterus. Different types of genetic diseases have different risks of transmission to the offspring and have different requirements for the selection of an embryo suitable for transfer.
For families with a genetic burden, PGT-M is the only reliable method to rule out the transmission of serious hereditary diseases to the offspring. Each couple must undergo a series of different tests before being accepted into an assisted reproduction programme. A clinical expert carries out a comprehensive diagnostic assessment to get an idea of which stimulation protocol is suitable for the partner and which specific methods and procedures should be used in the IVF cycle. If it turns out that the partners belong to the risk group, the IVF specialist recommends pre-implantation embryo diagnostics, which begins with a consultation with a clinical geneticist.
The retrieved eggs are fertilised by IVF and cultivated for 5 days until the blastocyte stage. A micromanipulator is then used to remove a small group of cells from each embryo. This sample is sent to a genetic laboratory where it is analysed. The method is very gentle and poses no risk to the future foetus.
