Embryo Genetic Testing (PGT-A or PGT-M)
Embryo genetic testing is a modern technique used as part of in vitro fertilization (IVF) and allows the evaluation of the embryos’ genetic material before embryo transfer.
Through preimplantation genetic testing, physicians can identify embryos that have a greater chance of developing into a healthy pregnancy, thereby helping improve treatment outcomes and reduce the risk of miscarriage.
What is preimplantation genetic testing of embryos?
Preimplantation genetic testing of embryos is a specialized test performed on embryos created through in vitro fertilization. With this method, the genetic material of the embryos is examined before embryo transfer in order to detect possible chromosomal or genetic abnormalities.
The procedure involves taking a small number of cells from the embryo in the laboratory, which are then analyzed using advanced genetic techniques. Based on the test results, embryos that do not show genetic abnormalities are selected for transfer to the uterus.
Preimplantation testing is an important tool for couples facing fertility difficulties or those with an increased risk of passing on genetic diseases.
What types of preimplantation testing are available?
Preimplantation genetic testing includes different types of examinations, which are used depending on the reason for analyzing the embryos. The two most common types are PGT-A and PGT-M.
PGT-A (Preimplantation Genetic Testing for Aneuploidy)
PGT-A is used to detect chromosomal abnormalities in embryos, meaning cases where there is an extra or missing chromosome. Such abnormalities may affect embryo implantation or lead to miscarriage.
The method helps select embryos with a normal number of chromosomes, which have a greater chance of developing into a healthy pregnancy.
PGT-M (Preimplantation Genetic Testing for Monogenic Diseases)
PGT-M is applied when there is a risk of transmitting specific inherited diseases. The test allows the detection of genetic mutations associated with specific conditions before embryo transfer.
In this way, embryos that do not carry the specific genetic disease can be selected, reducing the risk of transmitting the condition to the child.
In which cases is embryo genetic testing recommended?
The test is often used in cases such as:
- recurrent miscarriages, where there may be chromosomal abnormalities in the embryos
- advanced maternal age, when the risk of chromosomal abnormalities increases
- multiple failed IVF attempts
- family history of genetic diseases
- carriers of inherited conditions, where there is a risk of transmitting a specific genetic mutation
In these cases, embryo genetic testing can help select embryos without genetic abnormalities, increasing the chances of achieving a healthy pregnancy.
The process
How is preimplantation genetic testing of embryos performed?
Collection of cells from the embryo
In an embryology laboratory, a small sample of cells is taken from the embryo.
Genetic analysis
The cells are examined using specialized genetic methods to identify potential abnormalities.
Evaluation of results
Experts are evaluating the results of the genetic testing of the embryos.
Selection of suitable embryos
Embryos that do not exhibit genetic abnormalities are selected.
Embryo transfer
The selected embryos are transferred to the uterus as part of the in vitro fertilization process.
Legal Framework for Embryo Genetic Testing (PGT) in Greece
In Greece, preimplantation genetic testing is governed by Law 3305/2005 and the updated guidelines of the National Authority of Medically Assisted Reproduction (EAIYA). PGT is permitted following an application and approval by the EAIYA, with the aim of preventing the transmission of genetic diseases or chromosomal abnormalities to the child.
PGT-M (for monogenic diseases)
Approval from the EAIYA is required, and mandatory genetic counseling by a geneticist must take place beforehand. Approval is granted provided it is documented that the couple carries genes responsible for a specific inherited disease.
Typical examples include thalassemia and cystic fibrosis. There is no age restriction—the indication is exclusively clinical/genetic.
PGT-A (for chromosomal aneuploidies)
Approval from the EAIYA is granted provided specific criteria are met, such as advanced reproductive age, recurrent miscarriages, or repeated failed IVF attempts.
More specifically:
- Women over 40 years old: PGT-A is approved freely due to the documented increase in chromosomal abnormalities with age.
- Women under 40 years old: documentation of a specific clinical indication is required—recurrent miscarriages or at least three failed IVF attempts.
In all cases, Greek law prohibits the use of PGT for sex selection, except in cases of sex-linked diseases, and the procedure must be accompanied by genetic counseling.
Success rates of preimplantation genetic testing
Preimplantation genetic testing can help improve IVF outcomes, as it allows the selection of embryos without chromosomal or genetic abnormalities.
The effectiveness of the method depends on various factors, such as the woman’s age, the quality of the embryos, and the couple’s medical history. In many cases, the use of preimplantation testing can increase the chances of achieving a healthy pregnancy and reduce the risk of miscarriage.
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