Embryo genetic testing, also known as preimplantation genetic testing or PGT, is a laboratory examination that evaluates the chromosomal or genetic structure of an embryo before it is transferred to the uterus during in-vitro fertilization (IVF) treatment.
This examination is not necessary for every couple. Sometimes embryo evaluation relies on microscopic appearance; sometimes information at the chromosomal or genetic level contributes to the decision-making process. The couple's history and clinical presentation determine whether the test is needed.
No genetic test alone guarantees a healthy baby or pregnancy. The test provides a layer of information that supports the decision.
In Izmir, the decision for embryo genetic testing for couples planning IVF treatment is made based on the medical history, the purpose of the test, and the expected benefit. You can schedule an appointment with Assoc. Prof. Dr. Funda Göde to evaluate the suitability of PGT options for you.
Genetic testing of embryos is the examination of a small sample taken from an embryo developed in the IVF laboratory to evaluate either the number of chromosomes or a specific gene. The test can only be performed during an in vitro fertilization (IVF) process, as the embryos must be available in the laboratory.
PGT-A is a screening and embryo selection test that evaluates chromosome copy number before embryo transfer. PGT-M and PGT-SR are targeted tests performed for previously identified genetic risks.
Ultrasound during pregnancy, first-trimester combined screening, and cell-free fetal DNA testing are screening tests. Chorionic villus sampling (CVS) and amniocentesis are diagnostic tests. A PGT result does not completely replace these prenatal evaluations performed during pregnancy.
The aim of preimplantation genetic testing is to help identify the most suitable embryo for transfer. With PGT-A, embryos with the expected chromosome number are prioritized for transfer. When a known genetic disease is present, PGT-M and PGT-SR help evaluate that disease or an unbalanced chromosomal structure.
The expected benefit depends on the type of PGT being performed. PGT-M and PGT-SR evaluate embryos for a known genetic risk. PGT-A may provide additional information for embryo selection in selected cases. However, PGT-A has not been shown to increase the overall live birth rate in every patient group. No type of PGT can guarantee pregnancy.
There are three main tests, each designed to answer different clinical questions. The type of genetic testing used during IVF is determined according to the couple's medical history and clinical findings.
PGT-A stands for Preimplantation Genetic Testing for Aneuploidy. Before embryo transfer, it evaluates chromosome copy number in a cell sample taken from the outer layer of the blastocyst. A result described as "euploid" indicates that the expected number of chromosomes was detected in the analyzed cells. However, the sampled cells may not always represent the entire embryo. A PGT-A result does not exclude all genetic diseases or guarantee a healthy pregnancy.
As maternal age increases, chromosomal abnormalities become more common in embryos. Most of these abnormalities arise naturally during the aging process of the egg.
PGT-M is a test for monogenic (single-gene) disorders. If there is a known single-gene disease in the family or if the couple carries the disease, embryos can be evaluated for that specific genetic condition. Cystic fibrosis and Huntington's disease are examples of conditions evaluated with this method. PGT-M is considered when there is a known and clearly identified genetic disorder.
PGT-SR is designed for structural chromosomal rearrangements. Some individuals carry balanced chromosomal rearrangements (translocations). These individuals are usually healthy themselves, but their embryos may develop with unbalanced chromosomal structures. PGT-SR helps identify embryos carrying these unbalanced rearrangements.
The process begins with IVF treatment. Eggs are collected, fertilized in the laboratory, and the embryos are usually cultured until the blastocyst stage.
During the biopsy, a small sample is taken from the trophectoderm cells located in the outer layer of the blastocyst. These cells mainly contribute to the formation of the placenta. The inner cell mass, which develops into the baby, is intended to remain protected.
Compared with biopsies performed at earlier stages of embryo development, trophectoderm biopsy is considered to have a lower impact on the embryo. However, the possibility of some effect on the embryo cannot be completely excluded. The laboratory analysis method is selected according to the type of PGT being performed.
In PGT-A, methods such as next-generation sequencing (NGS) may be used to evaluate chromosome copy number. In PGT-M, a customized testing protocol may be required for the specific genetic variant identified within the family.
Following biopsy, embryos are generally cryopreserved using vitrification while awaiting the genetic report. Once the results are available, the embryo status and clinical plan are reviewed together, and a frozen embryo transfer may be scheduled. The reporting time varies depending on the laboratory and the type of genetic test used. The expected timeline is discussed during treatment planning.
In recent years, non-invasive approaches that do not require embryo biopsy have also been investigated. One example is the analysis of genetic material released into the embryo culture medium. Although these methods are promising, they have not yet replaced standard clinical practice.
Making a decision about embryo genetic testing becomes clearer with the right questions and a personalized treatment plan. To evaluate your genetic testing options according to your individual clinical circumstances,
You may contact Assoc. Prof. Dr. Funda Göde in İzmir. Together, we can plan your IVF treatment based on the latest scientific evidence.
Genetic testing is most clearly indicated for couples with a known inherited genetic risk. If there is a known single-gene disorder or carrier status within the family, PGT-M may be considered. If one partner carries a balanced chromosomal translocation, PGT-SR may be appropriate. In both situations, the goal is to determine whether the known genetic condition or chromosomal imbalance has been passed on to the embryos.
PGT-A may be considered for selected patients with advanced maternal age or repeated implantation failure. However, age alone is not sufficient to make this decision. Ovarian reserve, the expected number of embryos, previous treatment outcomes, and the couple's priorities should all be evaluated together. Current evidence does not conclusively show that PGT-A increases the overall live birth rate in these patient groups. Evidence supporting its routine use in recurrent pregnancy loss is also limited.
Following PGT-A, embryos are generally classified into several categories. One group consists of embryos with the expected chromosome number. Another group includes embryos with missing or extra chromosomes. A third category is known as mosaic embryos.
Mosaicism refers to the presence of different cell populations with different chromosomal structures within the same embryo. In some cases, the result falls between these two extremes. One reason is that the analysis is based on a very small number of sampled cells; when only a limited sample is analyzed, the result may remain statistically borderline. Such a result does not necessarily mean that the embryo should be discarded. Mosaic embryos can implant successfully and may result in the birth of apparently healthy babies, although implantation rates may be lower depending on the type of mosaicism.
Potential benefits of genetic testing include helping prioritize embryos for transfer and evaluating known single-gene disorders or chromosomal imbalances (PGT-M and PGT-SR).
The limitations are just as important as the advantages. Genetic testing can only be performed during IVF treatment and requires embryo biopsy. In some embryos, the results may be mosaic or inconclusive.
After evaluation, the number of embryos suitable for transfer may decrease, which may result in no embryo transfer during that treatment cycle. Therefore, current clinical guidelines do not recommend routine use of PGT-A for all patients with the aim of increasing live birth rates.
In treatment cycles involving genetic testing, embryos are usually frozen, and frozen embryo transfer is planned after the genetic results become available. In most cases, a single suitable blastocyst is selected for transfer, helping reduce the risk of multiple pregnancy.
The timing of transfer is determined by matching the developmental stage of the embryo with endometrial preparation. The duration of progesterone treatment, the embryo's condition after warming, and laboratory evaluation are all part of this planning process. References to a Day 5 or Day 6 embryo describe the developmental stage of the blastocyst rather than the transfer date itself.
A PGT result does not replace prenatal genetic evaluation during pregnancy. If pregnancy occurs, prenatal screening and diagnostic options are reconsidered according to the type of PGT performed and the test results. Genetic counseling is particularly valuable following PGT-M, PGT-SR, or mosaic embryo transfer.
The first step in embryo genetic testing in İzmir is determining whether the test is appropriate for the couple's individual circumstances. Maternal age, previous pregnancy and treatment history, known genetic risks within the family, and the condition of the available embryos all contribute to this evaluation.
Every decision is personalized. In practice, four main factors are considered:
The cost of genetic testing varies depending on the type of test, the number of embryos to be analyzed, and the laboratory procedures required. Genetic counseling, embryo biopsy, freezing, and thawing procedures may all be included in the overall treatment cost. In PGT-M applications, a customized test preparation may be necessary for the specific genetic variant identified within the family. Current pricing information is provided after the treatment plan has been finalized.
Kaynakça
Practice Committees of the American Society for Reproductive Medicine and the Society for Assisted Reproductive Technology. The use of preimplantation genetic testing for aneuploidy: a committee opinion. Fertil Steril. 2024;122(3):421-434.
National Institute for Health and Care Excellence. Fertility problems: assessment and treatment. NICE guideline NG257. London: NICE; 2026.
Practice Committee of the American Society for Reproductive Medicine. Indications and management of preimplantation genetic testing for monogenic conditions: a committee opinion. Fertil Steril. 2023.
Practice Committee of the American Society for Reproductive Medicine. Clinical management of mosaic results from preimplantation genetic testing for aneuploidy of blastocysts: a committee opinion. 2023.
American College of Obstetricians and Gynecologists. Preimplantation Genetic Testing. ACOG Committee Opinion No. 799. Obstet Gynecol. 2020;135:e133-e137.
del Arco de la Paz A, Giménez-Rodríguez C, Selntigia A, Meseguer M, Galliano D. Advancements and challenges in preimplantation genetic testing for aneuploidies: in the pathway to non-invasive techniques. Genes. 2024;15(12):1613.
The choice of test varies. PGT-A assesses the embryo's chromosome number, PGT-M evaluates a known single-gene disorder in the family, and PGT-SR assesses structural changes where chromosomes are unevenly distributed. Which test is necessary is determined based on the couple's history.
The sample is taken from the outer layer of the blastocyst, which will later contribute to the placenta. This method has a lower impact on embryo development compared to biopsy performed earlier. The risk is not zero. The biopsy, freezing, and thawing stages must be carried out in an experienced laboratory.
Genetic testing can help prioritize suitable embryos for transfer and assess for known genetic diseases. This information is valuable, but it does not guarantee pregnancy or a healthy baby.
Genetic testing is not a guaranteed success rate for every couple. It is considered in select cases, when a person's genetic and clinical profile suggests a potential contribution. The goal is to avoid unnecessary procedures and only use the test when it can truly benefit you.
The duration varies depending on the laboratory and center used. In genetic testing cycles, embryos are frozen and the transfer is planned after the results are received, so the process may not be limited to a single treatment cycle. We will clearly share your personalized schedule during the planning consultation.
No. Genetic testing is not necessary for every couple. It is most often considered when there is a known single-gene disorder or translocation carrier status in the family. PGT-A, on the other hand, is evaluated on an individual basis according to age, history, and previous treatment results.
Note: This content is for general informational purposes only and does not replace diagnosis or treatment. A physician evaluation is required for personal diagnosis and treatment planning.
