Preimplantation Genetic Testing (PGT)

Preimplantation Genetic Testing (PGT) is a type of genetic screening test that is performed on embryos prior to transfer. The main purpose of PGT is to identify which embryos are more likely to result in an on-going pregnancy and prioritize embryos for transfer. 

There are three main types of PGT:

1. PGT-A (also known as PGT for aneuploidies): This type of PGT screens embryos for numerical chromosomal abnormalities, such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13). Biopsy for PGT-A can be performed on day 5 or day 6 of embryonic development.
2. PGT-M (also known as PGT for monogenic/single gene disorders): This type of PGT screens embryos for specific genetic disorders caused by mutations in a single gene, such as cystic fibrosis, sickle cell anemia, and Tay-Sachs disease. PGT-M requires the use of specialized techniques. Biopsy for PGT-M can be performed on day 5 or day 6 of embryonic development.
3. PGT-SR (also known as PGT for structural rearrangements): This type of PGT screens embryos for chromosomal rearrangements, such as translocations and inversions, that can cause infertility or increase the risk of miscarriage. PGT-SR requires the use of specialized techniques, which can be initiated and performed on day 5 or day 6 of embryonic development.

Advantages of PGT:

• Improving the chances of an ongoing pregnancy by selecting embryos that have a negative screen for genetic abnormalities
• Reducing the risk of miscarriage by avoiding the transfer of embryos with chromosomal abnormalities
• Decreasing the risk of passing on inherited genetic disorders to offspring
• Helping individuals and couples with a family history of genetic disorders to make informed decisions about starting a family

Limitations of PGT:

• PGT is an invasive procedure that involves the biopsy of five to ten cells from the developing embryo, also known as a blastocyst, which carries a small risk of harm to the embryo
• PGT is expensive and not covered by all insurance plans, which can make it difficult for some individuals and couples to access
• PGT does not guarantee a healthy pregnancy or a healthy baby, as other factors, such as environmental and lifestyle factors, can also affect fetal development and health
• PGT results can be inconclusive, which can lead to uncertainty and anxiety for individuals and couples
• PGT may also raise ethical and moral questions, such as the use of genetic testing to select embryos based on traits or characteristics that are not medically necessary

If you would like to know more about PGT, please schedule a pre-test genetic counselling session.

If you have had PGT on your embryos and would like a second opinion on the results, please schedule a comprehensive genetic counselling appointment. All results are reviewed by a clinical and laboratory geneticist to ensure you are provided with the most relevant and recent recommendations.