A question that paves the way for the PGTA test

You’re about to begin a surrogacy process and some questions arise: Is it possible to know before pregnancy if the embryo is at risk of any disease? Is there a test that can give us clues, without waiting for pregnancy or birth? This question leads us to the heart of this article: the PGTA test, and how it can help determine the embryo’s genetics before transfer.

Let’s explore together: what the PGTA test is, how it fits into a surrogacy process, what it can and cannot reveal about the embryo’s genetics, the benefits, limitations, and decisions that prospective parents need to know.

What is the PGTA test?

In our previous article, Is it possible to select the sex of the baby in surrogacy using the PGTA test? (link to article from 04/11) we discussed how the PGTA test (also known as PGT-A , from the English Preimplantation Genetic Testing for Aneuploidy) can help us identify the sex of the baby before pregnancy.

Additionally, this test analyzes whether the embryo has the correct number of chromosomes—that is, whether there are any aneuploidies, such as having extra or missing chromosomes—which is fundamental to ensuring proper development.

However, when we talk about “identifying potential genetic diseases in the embryo” thanks to the PGTA test, it’s important to clarify that this technique doesn’t detect all genetic diseases. Its main function is to identify alterations in the number of chromosomes, which can influence embryo implantation, development, or even lead to chromosomal syndromes.

How is the PGTA test performed?

Let’s look at the process step by step, in a simple way:

1. During an IVF cycle (or within a surrogacy process where the embryo is created in the laboratory) embryos are obtained (generally up to the blastocyst stage, day 5 or 6).
2. Tissue sampling is performed on an embryo: the embryologist extracts one or more cells from the embryo (usually from the trophectoderm, which is the part that will give rise to the placenta) without affecting, as far as possible, its viability.
3. These cells are genetically analyzed: using techniques such as next generation sequencing (NGS), the number of chromosomes (the 23 pairs) is determined and they are classified as “euploid” (normal number) or “aneploid” (altered number) or even “mosaic”.
4. Based on the result, a decision is made as to which embryo(s) have the highest probability of implantation and the lowest risk of miscarriage or other complications.
5. In a surrogacy process, the selected embryo is transferred to the surrogate’s uterus. This technique is thus integrated into the surrogacy program.

Why might it be useful in a surrogacy process?

When we talk about surrogacy, intended parents typically go through several complex steps: donor or gamete selection, embryo creation, transfer, decision about the surrogate, etc. Incorporating the PGTA test into the process can offer the following benefits:

• Improving embryo selection: By knowing the embryo’s genetic makeup (in chromosomal terms) before implantation, the likelihood of selecting the chosen embryo increases, reducing the risk of implantation failure. In other words, PGTA allows for the selection of chromosomally normal embryos from among all of a patient’s developing embryos.
• Reducing the risk of miscarriage: By avoiding the transfer of embryos with serious chromosomal abnormalities, the likelihood of a miscarriage is reduced.
• Optimizing the IVF/surrogacy cycle: sometimes resources, time, and emotions are heavily involved; a more informed selection can avoid failed cycles that increase stress and costs.
• Transparency for prospective parents: For those opting for surrogacy, knowing that the PGTA test has been performed can provide peace of mind and greater control over the process.

In summary, the PGTA test is a valuable tool in the surrogacy process. Its purpose is to ensure the health and viability of the embryo before it is transferred to the surrogate, providing peace of mind and confidence to the intended parents.

What genetic diseases can the PGTA test detect? And which ones can’t it detect?

This is where it’s important to be very clear. Because the phrase “to know the possible genetic diseases of the embryo” suggests a broad scope, when in reality the test refers mainly to chromosomal abnormalities (aneuploidies) and not to all genetic variants or individual mutations. Let’s differentiate:

What does the PGTA test detect?

• Alterations in the total number of chromosomes in the embryo (for example , having 47 instead of 46, organized into 23 pairs) that can lead to syndromes such as trisomy 21, trisomy 18, monosomy X, etc.
• Large alterations in chromosomal structure in some cases (depending on the laboratory).
• Identification of euploid embryos (correct number of chromosomes) versus aneuploid embryos.

What can’t the PGTA test detect?

• It does not detect all individual genetic diseases caused by single gene mutations (those are covered by another test: the so-called PGT-M).
• It cannot guarantee that an embryo labeled as “normal” (euploid) will implant successfully or that there will be no problems during pregnancy or at birth. For example, according to the American Society for American Society for Reproductive Medicine (ASRM): “The value of PGT-A as a routine test for all patients undergoing IVF has not been demonstrated.”
• It is not a “guarantee of a healthy baby.” The embryo’s genetics are only one of the factors that influence it (the mother’s health, the environment, other epigenetic aspects , etc., also play a role).
• It does not detect all genetic variants or small or complex mutations (e.g., multiple recessive diseases, point mutations, etc.) unless PGT-M is used in addition.

So what is meant by “genetics of the embryo”?

When we talk about “embryo genetics” in this context, we are primarily referring to the embryo’s chromosomal genetics (i.e., whether the embryo has the correct number of chromosomes). In more common usage, “embryo genetics” might imply inherited diseases, but it’s important to clarify that the PGTA test does not cover all of them. In short: the PGTA test allows us to identify certain chromosomal abnormalities in the embryo, which is an important part, but not the whole picture, of embryo genetics.

When is the PGTA test recommended in surrogacy?

In a surrogacy process, the decision to perform the PGT-A test will depend on several factors. Some of the most frequent scenarios are:

• Age of the donor or eggs: if the eggs come from an older woman, the risk of aneuploidy is higher, so the PGTA test may make more sense.
• History of implantation failure or recurrent miscarriages. In these situations, chromosomal selection of the embryo may be valuable.
• Desire to optimize the surrogacy cycle, especially if there are few embryos available, or if only one embryo is to be transferred (thus reducing the risk of multiple pregnancy).
• Budget and risk assessment: Like any additional technique, the PGTA test involves costs and minor risks related to the embryo biopsy (although these risks are small). Therefore, prospective parents and the team should assess whether the test offers a clear benefit in their case.

It is important to emphasize that the PGT-A test is not automatically recommended for all cases, and it should be clearly explained what patients can and cannot expect. The ASRM cautions: “The value of routine PGT-A testing for all patients has not been demonstrated.”

What are the specific benefits of the PGTA test?

We list the main benefits in clear language, so that anyone can understand them:

• Higher probability of choosing a “chromosomally normal” embryo: when using the PGTA test, a euploid embryo may be preferred over an aneuploid one, which improves the chances of success.
• Reduced risk of miscarriage: By avoiding the transfer of embryos with chromosomal abnormalities, the possibility of premature termination of pregnancy is reduced.
• Optimization of the surrogacy process: less uncertainty, fewer failed cycles, less emotional strain for prospective parents.
• More informed choice: parents who use surrogacy feel more in control when they know the results of the PGTA test before the transfer.

How to interpret the results of the PGTA test in the context of surrogacy?

When the PGTA test results come in, expectant parents need to understand what they mean and how to deal with them. Here are some practical tips:

• If it’s euploidy: this means that, in that chromosomal analysis, the number of chromosomes is correct. This is a good sign for the transfer, but it doesn’t guarantee 100% success.
• If it’s aneuploidy: this means there’s an extra chromosome, a missing chromosome, or a significant abnormality. In many cases, that embryo is discarded for transfer because the risk of failure or miscarriage is higher.
• If the embryo is mosaic: some tests detect that some cells are normal and others are not. This situation requires further analysis and discussion with the medical team regarding risks, the possibility of transfer, etc.
• In the surrogacy process, you should discuss with the clinic or specialized center: how many embryos did we generate?, how many were biopsied?, what percentage were euploid?, what is the transfer strategy?
• It’s also important to combine the PGTA test result with other key factors: the surrogate’s health, the quality of the laboratory, experience in embryo transfer, etc. It’s not just about the embryo’s genetics, but about the entire environment.

How does the PGTA test fit into the surrogacy workflow?

To understand this better, let’s imagine the typical flow:

Gamete/donor selection (eggs, sperm) → In vitro fertilization and culture to blastocyst → Embryo biopsy and PGTA test → Results, selection of euploid or best chromosomally classified embryos → Embryo transfer to the surrogate (in the case of surrogacy) → Pregnancy monitoring until delivery.

In this process, the PGTA test acts as a filter for information about the embryo’s genetics, helping to make more informed decisions before transfer. Thus, for those using surrogacy, the PGTA test represents an additional tool for safety and process optimization.

Recommendations for prospective parents considering the PGTA test in surrogacy

Here are some recommendations to help you make informed decisions:

• Look for experience and good references in the PGTA test. For more information, you can contact our family advisor (link to calendar).
• Ask how many embryos they have in their cycle, how many were evaluated, and how many turned out to be euploid. That gives you an idea of the real picture.
• Verify that the surrogate mother (in the case of surrogacy) is in good health and that the transfer environment is optimal; the genetics of the embryo are important, but they are not everything.
• Ask for a clear explanation of the results: what do “euploid”, “aneploid”, and “mosaic” mean? Make sure you understand the terms.
• Consider the additional cost and weigh it against the potential benefit in your case.
• Have realistic expectations: the PGTA test improves odds, but doesn’t guarantee success. Being emotionally prepared is also key.
• Talk to your fertility specialist: depending on your history (donor’s age, number of embryos, history of miscarriages, etc.) the recommendation may vary.

Conclusion

The preimplantation genetic testing (PGTA) test is a powerful tool in the field of assisted reproduction and surrogacy. It allows for the identification of the embryo’s genetic makeup in chromosomal terms before implantation, which can increase the chances of success, optimize resources, and provide greater confidence to prospective parents. However, it is not a magic bullet: it has limitations, costs, does not detect all genetic diseases, and does not guarantee a perfect pregnancy.

If you are considering surrogacy, Gestlife will ensure you understand the implications of the PGTA test, weigh the benefits and costs, and maintain realistic expectations. Ultimately, it’s about making an informed, supported, and conscious decision.

Frequently Asked Questions ( FAQs )

Does the PGTA test guarantee that the baby will be born healthy?

No. The PGTA test analyzes the number of chromosomes in the embryo, which is an important factor, but it does not detect all genetic diseases. Furthermore, other factors (the mother, the environment, other genes) also play a role.

When is the PGTA test recommended in a surrogacy process?

It is especially recommended when the donor is of advanced maternal age, when there is a history of miscarriages or implantation failures, or when there are few embryos available. However, it is not mandatory in all cases.

Is the PGTA test very expensive or risky?

It could have additional costs, and taking tissue samples from the embryo carries a small risk. This should be weighed against the potential benefits in each specific case.

If the embryo is euploid , can the others be discarded?

Not necessarily discarded, but priority is given. If there is only one euploid embryo, that one is usually transferred first. The others can be kept in reserve or other options can be considered.

Is it possible for the PGTA test to say an embryo is “abnormal” and then result in a healthy baby?

Yes, in some cases the results may not be 100% conclusive. There are cases of embryos categorized as aneuploid that have later resulted in healthy babies. That’s why careful interpretation is required.

Does the PGTA test replace other genetic tests?

No. The PGTA focuses on whole chromosomes (aneuploidies). If you want to detect a specific genetic disease caused by a point mutation or recessive diseases, you need the PGT-M test or other specialized genetic tests.

What should I ask my specialist if I’m considering the PGTA test?

How many embryos were evaluated, how many were euploid, what technology they use (NGS or other), what their success rates are, what their experience is with surrogacy, what the cost is, what risks are involved, and what the transfer strategy is in that specific case.