Preimplantation
Genetic Testing (PGT)

Preimplantation Genetic Testing (PGT)

Preimplantation Genetic Testing (PGT), earlier known as Preimplantation Genetic Diagnosis (PGD), is a specialized genetic testing technique used during in vitro fertilization (IVF) to identify specific inherited genetic conditions in embryos before they are transferred to the uterus. In this process, a few cells are carefully taken from the developing embryo and examined in a laboratory to check for known genetic mutations or abnormalities.

PGT is mainly recommended for couples who carry certain genetic conditions or have a family history of inherited diseases, as it helps in selecting embryos that are free from those disorders and supports the chances of a healthy pregnancy.

PGT and Its Types: PGT-A, PGT-M, and PGT-SR

Preimplantation Genetic Testing (PGT) includes different types of tests that are used during IVF to check embryos for genetic or chromosomal problems before they are transferred to the uterus. Each type of PGT is designed for a specific purpose, depending on the couple’s medical history and the kind of genetic risk involved.

The main types of PGT include:

PGT-A (Preimplantation Genetic Testing for Aneuploidy): This test checks whether the embryo has the correct number of chromosomes. It helps identify embryos with extra or missing chromosomes, which can affect implantation or lead to miscarriage.

PGT-M (Preimplantation Genetic Testing for Monogenic Disorders): This type is used when there is a known genetic condition in the family caused by a single gene. It helps detect specific inherited diseases and allows doctors to select embryos that do not carry that condition.
PGT-SR (Preimplantation Genetic Testing for Structural Rearrangements): This test is recommended when one of the parents has a structural change in their chromosomes, such as a translocation. It helps identify embryos with a balanced chromosomal structure.

The choice of which type of PGT to use depends on the couple’s medical background and the advice of the fertility specialist.

Who Should Consider PGT?

Preimplantation Genetic Testing (PGT) may be recommended for couples who have a higher chance of passing certain inherited genetic conditions to their child. This testing is usually considered when there is a known genetic risk in the family or when doctors want to reduce the chances of a genetic disorder being passed to the baby during IVF treatment.

PGT may be considered in the following situations:

When one or both partners are carriers of a known genetic disorder.
If there is a family history of inherited diseases.
When a couple has previously had a child with a genetic condition.
If there have been repeated pregnancy losses where a genetic factor may be involved.
When doctors want to reduce the risk of passing specific genetic mutations to the baby.

Why is PGT Recommended in IVF Treatment?

Preimplantation Genetic Testing (PGT) is recommended in IVF to check embryos for certain inherited genetic conditions before they are placed in the uterus. This helps doctors identify embryos that do not carry specific genetic disorders, which can reduce the chances of passing these conditions to the baby and support a healthier pregnancy.

PGT may be recommended to:

Reduce the risk of inherited genetic diseases
Identify embryos without specific genetic mutations
Help doctors select healthier embryos for transfer
Lower the chances of certain genetic conditions in the baby
Support safer and more informed embryo selection during IVF

Conditions That Can Be Detected with PGT

PGT is used to identify genetic and chromosomal conditions in embryos before they are transferred during IVF. It includes different types of testing based on the concern. PGT-M checks for single gene disorders that can be passed from parents to children, especially when a specific condition is known in the family. PGT-A is used to detect chromosomal abnormalities, such as extra or missing chromosomes. PGT-SR is used to identify structural chromosome issues, like translocations, and helps in selecting embryos with a balanced chromosomal structure.

Some examples of conditions that PGT may help detect include:

Thalassemia
Cystic Fibrosis
Sickle Cell Disease
Huntington’s Disease
Muscular Dystrophy
Tay-Sachs Disease
Certain inherited metabolic disorders

How Does the PGT Process Work?

Preimplantation Genetic Testing is performed as part of the IVF process to check embryos for specific genetic conditions before they are transferred to the uterus. The aim is to identify embryos that do not carry the particular genetic disorder being tested. The testing is done at a very early stage of embryo development in a specialized laboratory.

The PGT process usually involves the following steps:

Egg retrieval and fertilization: The woman’s eggs are collected and fertilized with sperm in the laboratory to create embryos.
Embryo development: The embryos are allowed to grow in the lab for a few days until they reach a suitable stage for testing.
Embryo biopsy: A few cells are carefully taken from each embryo without affecting its overall development.
Genetic testing: The removed cells are examined in the laboratory to check for the specific genetic condition.
Embryo selection: Embryos that do not carry the tested genetic disorder may be chosen for transfer to the uterus.

Closing Words

Preimplantation Genetic Testing (PGT) is an important advancement in IVF that helps doctors identify genetic and chromosomal conditions in embryos before transfer. With different types such as PGT-A, PGT-M, and PGT-SR, this testing allows a more detailed evaluation based on the couple’s specific needs and medical history, supporting better embryo selection and improving the chances of a healthy pregnancy.

However, the decision to use PGT or any of its types should always be made after proper medical guidance. Consulting with a fertility specialist can help couples understand which type of testing is suitable for their individual condition and treatment plan.

PGT

Preimplantation Genetic Testing (PGT)