Understanding PGT-A Mosaicism in Thailand: A Guide for Patients

What Is PGT-A Mosaicism?

When you undergo preimplantation genetic testing for aneuploidy (PGT-A) during IVF, the laboratory analyzes a small sample of cells from each embryo. The results typically classify embryos as euploid (normal chromosome number), aneuploid (abnormal chromosome number), or mosaic. A mosaic embryo contains a mixture of cells: some with the normal number of chromosomes and some with an abnormal number. This is different from a uniformly aneuploid embryo, where all cells show the same abnormality.

Mosaicism is reported as a percentage, such as 20% or 40%, indicating the proportion of abnormal cells detected in the biopsy sample. However, this percentage is an estimate based on the small sample tested and may not perfectly reflect the entire embryo. The interpretation of mosaic results is complex and evolving, and it is important to discuss your specific results with a genetic counselor.

How Are Mosaic Embryos Reported in PGT-A Results?

PGT-A results typically categorize embryos into three main groups: euploid, aneuploid, and mosaic. Mosaic results may be further described as low-level or high-level mosaicism, depending on the percentage of abnormal cells. Some laboratories also specify which chromosomes are affected and whether the abnormality is a gain or loss of genetic material.

Because there is no universal standard for reporting mosaicism, different clinics and laboratories may use slightly different criteria. This means that the same embryo could be classified differently by another lab. It is essential to ask your clinic how they define and report mosaicism, and what their experience is with mosaic embryo transfers.

What Does a Mosaic Result Mean for Your Embryo?

A mosaic result does not necessarily mean the embryo is abnormal or cannot lead to a healthy baby. In some cases, mosaic embryos may self-correct during development, or the abnormal cells may be confined to the placenta rather than the fetus. However, the outcomes are not guaranteed, and there is a risk of an ongoing pregnancy with chromosomal abnormalities.

The decision to transfer a mosaic embryo involves balancing the potential for a healthy live birth against the risk of miscarriage or a child with a chromosomal condition. This decision is highly personal and should be made in consultation with your medical team and a genetic counselor who can explain the specific risks based on your embryo’s mosaic pattern.

Why Genetic Counseling Is Essential

Genetic counseling is a critical step when you receive a mosaic PGT-A result. A genetic counselor can help you understand the technical aspects of mosaicism, interpret your specific results, and discuss the potential outcomes and risks. They can also explain the limitations of PGT-A, including the fact that it does not test for all genetic conditions and cannot guarantee a healthy baby.

In Thailand, genetic counseling services may be available at your fertility clinic or through a referral. It is important to ask your clinic about the availability of genetic counseling and to prepare questions before your appointment. A counselor can also help you consider alternative options, such as further testing or using a different embryo.

Questions to Ask Your Clinic About Mosaic Embryos

When discussing mosaic results with your clinic, consider asking the following questions:

• How does your laboratory define and report mosaicism?
• What percentage of abnormal cells is considered low-level versus high-level mosaicism?
• Which chromosomes are affected in my embryo, and what is the specific abnormality?
• What is your clinic’s experience with transferring mosaic embryos?
• What are the potential risks and outcomes for this specific mosaic pattern?
• Are there any additional tests that could provide more information?
• What is the process for genetic counseling, and can I speak with a counselor?

Next Steps: Making an Informed Decision

After receiving a mosaic result, take time to gather information and consult with your medical team. Here is a step-by-step approach:

1. Request a detailed explanation of your PGT-A report from your clinic.
2. Schedule a genetic counseling session to discuss the implications.
3. Ask about the likelihood of a healthy live birth with your specific mosaic embryo, based on available research and your clinic’s data.
4. Consider your personal values and risk tolerance when making a decision.
5. Discuss alternative options, such as using a euploid embryo if available, or undergoing further testing.

Remember that PGT-A is a screening tool, not a guarantee. It can reduce the risk of transferring an embryo with a chromosomal abnormality, but it cannot eliminate all risks. Your decision should be based on the best available information and your own preferences.

For more general information about PGT in Thailand, see our PGT in Thailand guide. You may also find our other guides helpful, or check the FAQ section for common questions.

Frequently asked questions

What is a mosaic embryo in PGT-A?

A mosaic embryo has a mixture of cells with normal and abnormal chromosome numbers. PGT-A can detect this mosaicism, but the percentage is an estimate from a small biopsy sample.

Can a mosaic embryo lead to a healthy baby?

In some cases, yes, but outcomes are not guaranteed. Mosaic embryos may self-correct or have abnormal cells confined to the placenta. However, there is a risk of miscarriage or a child with a chromosomal condition. Genetic counseling is essential.

How is mosaicism reported in PGT-A results?

Mosaicism is typically reported as a percentage of abnormal cells, sometimes categorized as low-level or high-level. Reporting criteria can vary between laboratories, so it's important to ask your clinic for details.

Should I transfer a mosaic embryo?

The decision depends on your specific situation, the mosaic pattern, and your risk tolerance. Discuss with your fertility specialist and a genetic counselor to understand the potential risks and benefits.

Is genetic counseling available in Thailand for mosaic results?

Many fertility clinics in Thailand offer genetic counseling or can refer you to a counselor. Ask your clinic about availability and how to schedule a session.

Continue your research

• PGT in Thailand overview
• PGT and IVF guides
• Frequently asked questions

Medical information notice: This article is educational and does not replace individual assessment, diagnosis, genetic counselling or treatment advice from a licensed clinician. Provider services, availability, fees and policies should be verified directly before booking.