In today’s landscape of advanced reproductive medicine, Pre-Implantation Genetic Testing for Aneuploidy (PGT-A) stands out as a vital tool for couples embarking on fertility treatments. Here’s a closer look at what PGT-A involves, its purpose, and how it can impact your fertility journey.
What is PGT-A?
PGT-A is a genetic test that screens embryos for the correct number of chromosomes before implantation. This test, often requested by your fertility doctor, involves taking a biopsy of a few cells from an embryo at the five or six-day development stage. These cells are then analysed in the genetic testing laboratory to assess chromosomal integrity.
A healthy embryo has 46 chromosomes in each cell, but sometimes there may be extra or missing chromosomes, leading to what we call aneuploidy. Identifying aneuploid embryos helps avoid implantation of embryos with chromosomal abnormalities, which are less likely to result in a healthy pregnancy. By selecting embryos with the correct number of chromosomes, known as euploid embryos, we increase the chances of a successful pregnancy.
Who Can Benefit from PGT-A?
PGT-A is particularly recommended for certain groups, including:
- Women of Advanced Maternal Age: The likelihood of chromosomal abnormalities increases with maternal age, so women over a certain age are often advised to undergo PGT-A.
- Couples with a History of Pregnancy Loss: Recurrent miscarriages can sometimes be due to chromosomal abnormalities, so identifying these issues before implantation may help prevent further losses.
- Those Experiencing Recurrent Implantation Failure: If previous attempts at implantation have failed, PGT-A can help determine whether chromosomal abnormalities might have been a contributing factor.
Understanding Your PGT-A Results
After analysis, PGT-A results fall into three main categories:
- Euploid: These embryos have 46 chromosomes, which is ideal, and are most likely to lead to a healthy pregnancy.
- Aneuploid: These embryos have either missing or extra chromosomes. They are generally not recommended for implantation due to the lower likelihood of resulting in a successful pregnancy.
- Mosaic: Mosaic embryos contain a mix of normal and abnormal cells. This result can be complex, and in such cases, a genetic counsellor will review the findings with you to determine the best path forward.
The Role of Genetic Counselors in PGT-A
Genetic counsellors are essential in helping you understand genetic tests like PGT-A. We provide guidance on what the results mean for your fertility journey and discuss potential next steps. If your results are challenging to interpret—such as in the case of mosaic embryos—a genetic counselor can offer insights on your options and help you make informed decisions.
Limitations of PGT-A
It’s important to know that while PGT-A is an advanced screening tool, it has limitations. For instance:
- Microdeletions and Duplications: PGT-A cannot detect small chromosome deletions or duplications, known as microdeletions or microduplications.
- Single Gene Disorders: Conditions such as cystic fibrosis or sickle cell disease cannot be identified with PGT-A.
- Complex Genetic Conditions: Disorders like autism, heart disease, or cancer involve complex genetics beyond what PGT-A can screen for.
PGT-A is a powerful tool for selecting embryos with the greatest chance of leading to a healthy pregnancy. Read more on Genetic Counsellor – committed to providing the insights and support you need to make the best choices for your fertility journey.
By Kelly Loggenberg, Genetics Counsellor at Next Biosciences