Genetics

Preimplantation genetic testing is a highly specialised technique designed to identify chromosomal aberrations (deviations and changes) or monogenic hereditary diseases before an embryo is transferred to the uterus. The main goal of the testing is to select only the embryos in which no abnormality was detected.

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Through the studying of chromosomal embryo construction it was discovered that the presence of aneuploidy (chromosome deviations) is one of the leading causes of infertility. The examination of the embryo chromosomes can increase the success rate of assisted reproduction. 

The indication for preimplantation genetic testing is most commonly due to the following factors:

  • High risk of chromosomal abnormalities, or serious monogenetic hereditary disease
  • Genetic deviations linked to the gender of the embryo
  • Numerous miscarriages
  • Previous early birth or abortion of an embryo with chromosomal abnormality
  • Numerous unsuccessful rounds of IVF
  • Higher age of the female partner

The pre-implantation genetic testing is performed in the early embryo development stage. After the mechanical opening of the zona pellucida, 5-10 cells are abstracted and they are investigated using one of the methods described below. The embryo biopsy is usually carried out on the 5th day after the fertilisation. Only the embryos that are found to be healthy are then chosen for the embryo transfer.

 The indication for all genetic testing is decided by the doctors.

PGT-A with NGS method

NGS - Next Generation Sequencing - is one of the most high-tech genetic testing methods. The testing is done on the cells that are taken from the embryos in the early blastocyst stage - the 5th day of development. It allows the early detection of structural problems, or any other deviations, on all 24 chromosomes. It is also highly sensitive to the detection of genetically abnormal embryos, having close to a zero mistake rate. NGS testing is especially suitable in cases where one of the partners is a carrier of a genetic disease, for couples who have had numerous miscarriages or for the more mature aged female partner. The indication for NGS is always decided by the doctor.

PGT-M with PCR method

PCR - Polymerase Chain Reaction: A diagnostic method aimed at the detection of specific inheritable genetic diseases. It is applicable for all known monogenic genetic mutations. If there is further suspicion from the doctor or any other reason for indication, further NGS examination is possible on the remaining healthy embryos.

PGT with FISH method

FISH - Fluorescence In Situ Hybridisation: A method of genetic testing, which is performed on 1 or 2 embryo cells. Those cells are taken out on day 3 of the embryos development. The FISH method allows the detection of various anomalies in chromosomes 13, 15, 16, 18, 21, 22, X and Y. It is impossible to test the aneuploidia in other chromosomes, which lowers the accuracy of this method. In comparison with NGS, there is a greater risk of false positive or false negative results. For this reason, the FISH method is nowadays considered outdated.

 

MATCH+

MATCH+ – an additional examination of the 600 most frequent genetic mutations (suitable mainly in therapies with egg donation). The examination ensures safe matching and optimal genetical compatibility of the donor and partner, while still respecting the phenotypical and other requests of the couple.

*Every person is a carrier of various mutations that do not have any impact on the person. However, in the case where two people with the same mutation partner, it may result in a higher risk of conceiving a genetically handicapped child.

 

Prenascan

Prenatal testing is performed based on the mother’s blood collection in the 10th week of pregnancy. This test allows us to discover the common chromosomal abnormalities with a single or twin pregnancy. This method is focused on trisomy detection and is recommended for females with marginal test results from the 1st trimester screening. This method is used almost exclusively with women who underwent assisted reproduction or with women above 35 years of age.

 

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