PGT (Preimplantation Genetic Diagnosis)

For couples planning to start a family, the most significant goal is ensuring the birth of a healthy child. Thanks to modern medical advancements, genetic issues can now be identified at the earliest possible stage—even before pregnancy begins.

Preimplantation Genetic Diagnosis (PGD/PGT) is the earliest method available for diagnosing genetic diseases. In this procedure, embryos fertilized in a laboratory are genetically analyzed before being transferred to the mother’s uterus. This process also provides the opportunity for gender selection.

This method is primarily utilized during IVF (In Vitro Fertilization) to screen embryos for hereditary conditions. It is particularly vital for individuals with a family history of genetic disorders who wish to prevent passing these conditions to their children. By analyzing embryos in a laboratory environment, specialists ensure that only genetically healthy embryos are selected for transfer.

In recent years, pre-transfer genetic screening has become a global standard. These examinations allow for a detailed analysis of genetic diseases that might manifest at birth or later in life. As a result, couples who are carriers of genetic disorders can confidently have healthy children.

What is Preimplantation Genetic Diagnosis (PGT)?

PGT stands for Preimplantation Genetic Diagnosis. It is the comprehensive genetic evaluation of embryos created in a laboratory setting before they are implanted into the mother’s womb.

Through this process, specific genetic disorders can be diagnosed, including:

• Cystic Fibrosis

• Fragile X Syndrome

• Myotonic Dystrophy

• Tay-Sachs Disease

• Thalassemia

Couples with known genetic risk factors can utilize this procedure to minimize the risk of having a child with a genetic disorder. PGT analysis is typically performed on the third or fifth day of embryo development.

How the Procedure Works:

• On the Third Day: When the embryo reaches the 7-8 cell stage, a biopsy is taken from 1 or 2 cells.

• On the Fifth Day (Blastocyst Stage): A biopsy is taken from the cells that will eventually form the placenta, providing a more comprehensive genetic map.

Why is PGT Recommended?

PGT is highly recommended in the following clinical scenarios:

• Advanced Maternal Age: To screen for age-related chromosomal abnormalities.

• Recurrent Miscarriages: To identify genetic factors that may prevent a pregnancy from reaching full term.

• Repeated IVF Failures: To ensure that the failure is not due to chromosomal issues.

• Known Genetic Risks: When one or both parents are carriers of a hereditary disease.

Advantages of PGT:

1. Detection of Chromosomal Abnormalities: Identifies issues like Down Syndrome before implantation.

2. Increased Pregnancy Rates: Healthy, screened embryos have a much higher chance of successful attachment to the uterine wall.

3. Reduced Miscarriage Risk: By selecting the most viable embryos, the likelihood of pregnancy loss is significantly lowered.

4. Gender Selection: Allows parents to balance their family according to their preferences.

Is PGT Performed for Everyone?

PGT is not a routine procedure performed for every couple. It is primarily preferred for couples who have a personal or family history of genetic disorders. It is also an essential application for couples identified as carriers of hereditary diseases to ensure they have a healthy child.

Preimplantation Genetic Diagnosis can be applied to children of couples with single-gene disorders or chromosomal structural abnormalities. Furthermore, PGT is recommended for couples where genetic alterations that may trigger cancer have been identified in their family history.

The decision to conduct a genetic screening is based on the couple’s request and the specialist’s evaluation. Following a detailed medical review and the identification of a genetic risk, PGT can be integrated into the treatment plan.

In Which Cases is PGT Recommended?

PGT is a specialized procedure requested under specific clinical circumstances. The conditions under which PGT is recommended include:

• Chromosomal Abnormalities: If either the prospective mother or father is a carrier of numerical or structural chromosomal disorders.

• History of Genetic Issues: Couples who have had a previous pregnancy or a child with a chromosomal disorder.

• Single-Gene Disorders: For conditions such as Thalassemia, Fanconi Anemia, and various immune system disorders.

• Carrier Status: When both partners are carriers of the same single-gene mutation or if one partner has a confirmed single-gene disorder.

• HLA Tissue Typing: When HLA typing is required for a sibling (e.g., for cases of Leukemia, Thalassemia, or Fanconi Anemia requiring stem cell compatibility).

• Genetic Predisposition: During the identification of diseases with a known genetic predisposition.

Does PGT Increase the Success Rate of IVF?

Since embryos in IVF are developed in a laboratory environment, PGT screening can be seamlessly performed before the embryo transfer. Experts emphasize that utilizing genetic diagnosis methods significantly enhances the chances of success in IVF treatments.

Clinical Benefits of PGT:

1. Higher Pregnancy Rates: It has been observed that PGT increases clinical pregnancy rates by selecting the most viable embryos.

2. Reduced Miscarriage Risk: The likelihood of pregnancy loss during the gestational period is significantly lowered when genetically healthy embryos are used.

3. Age and Fertility Factors: Even in couples without a known hereditary disease, the risk of chromosomal disorders can be high due to age.

Who Benefits Most from PGT in IVF?

• Prospective mothers over the age of 35.

• Women with a history of recurrent miscarriages.

• Couples who have experienced repeated IVF failures.

• Men with severe male factor infertility.

• Cases of unexplained infertility.

By integrating PGT, the overall success rate of IVF treatment is maximized, providing couples with the best possible path to a healthy pregnancy.