PGT-A vs PGT-M vs PGT-SR: Which Genetic Test Is Right for You?

If you are exploring IVF and genetic testing, you may have come across terms like PGT-A, PGT-M, and PGT-SR. These are three types of preimplantation genetic testing, each designed to answer a different question about embryos before transfer. This guide explains the differences in plain English, so you can have a more informed conversation with your fertility team.

At a Glance: The Three Main Types of PGT

• PGT-A checks embryos for an abnormal number of chromosomes (aneuploidy).
• PGT-M looks for a specific single-gene disorder that one or both parents carry.
• PGT-SR detects structural rearrangements of chromosomes, such as inversions or translocations.

Each test requires IVF, embryo biopsy, and genetic analysis. The choice depends on your medical history, family history, and the reason you are considering testing.

What Is PGT-A?

PGT-A, or preimplantation genetic testing for aneuploidy, screens embryos for the correct number of chromosomes. Humans typically have 46 chromosomes in each cell. An embryo with too many or too few chromosomes is called aneuploid. Most aneuploid embryos fail to implant or result in miscarriage. PGT-A aims to identify embryos with the expected number of chromosomes, which may help reduce the risk of miscarriage and improve the efficiency of IVF by selecting embryos more likely to develop normally.

PGT-A is often offered to patients of advanced maternal age, those with recurrent pregnancy loss, or those who have had multiple failed IVF cycles. However, it is not a guarantee of a healthy baby, and some embryos with normal chromosomes may still fail to implant or develop.

What Is PGT-M?

PGT-M, or preimplantation genetic testing for monogenic disorders, is used when there is a known single-gene condition in the family, such as cystic fibrosis, sickle cell disease, or Huntington’s disease. It identifies embryos that have inherited the specific genetic mutation. This test is typically offered to couples who are carriers of an autosomal recessive or dominant disorder, or who have a family history of a specific genetic condition.

PGT-M requires prior genetic testing of the parents to identify the exact mutation. The test is highly specific and can help reduce the risk of having a child affected by that particular disorder. However, it does not screen for all genetic conditions, and it requires careful genetic counseling before and after testing.

What Is PGT-SR?

PGT-SR, or preimplantation genetic testing for structural rearrangements, is used when one or both parents have a chromosomal rearrangement, such as a balanced translocation or inversion. These rearrangements usually do not cause health problems in the carrier, but they can lead to embryos with unbalanced chromosomes, which may cause miscarriage or birth defects. PGT-SR identifies embryos with a normal or balanced chromosome arrangement, increasing the chance of a successful pregnancy.

PGT-SR is typically recommended for couples where one partner has a known structural rearrangement, often identified after recurrent miscarriages or a child with a chromosomal abnormality.

How Do the Tests Differ?

Feature	PGT-A	PGT-M	PGT-SR
What it screens for	Abnormal number of chromosomes	Specific single-gene disorder	Structural chromosomal rearrangements
Who might consider it	Patients with advanced maternal age, recurrent miscarriage, or repeated IVF failure	Couples with a known single-gene disorder in the family	Couples where one partner has a balanced translocation or inversion
Requires prior genetic testing of parents?	No	Yes, to identify the specific mutation	Yes, to confirm the rearrangement
Main goal	Select embryos with the correct number of chromosomes	Avoid transferring embryos affected by a specific genetic disease	Avoid transferring embryos with unbalanced chromosomes

Which Test Is Right for You?

There is no one-size-fits-all answer. The right test depends on your medical and family history. Here are some general considerations:

• If you have no known genetic condition but are concerned about age-related chromosomal abnormalities, PGT-A may be discussed.
• If you or your partner are carriers of a specific genetic disease, PGT-M may be relevant.
• If you have experienced recurrent miscarriages and a chromosomal rearrangement has been identified, PGT-SR may be offered.

Your fertility clinic will recommend testing based on your individual situation. It is important to understand that PGT is not mandatory for all IVF patients, and it does not guarantee a successful pregnancy or a healthy child.

What to Consider Before Testing

Before deciding on PGT, consider the following:

• Genetic counseling: Speak with a genetic counselor to understand the implications of testing and results.
• Accuracy and limitations: No genetic test is 100% accurate. There is a small risk of misdiagnosis or inconclusive results.
• Embryo biopsy: The biopsy procedure is invasive, though the risk to the embryo is considered low.
• Cost and logistics: PGT adds to the cost of IVF and may require shipping samples to a specialized laboratory.
• Emotional readiness: Results may be complex, and you may face decisions about whether to transfer embryos with uncertain results.

Questions to Ask Your Clinic

• Which type of PGT do you recommend for my situation, and why?
• What is the laboratory’s experience with this specific test?
• How long will it take to receive results?
• What are the risks and limitations of the biopsy and testing?
• Will I have genetic counseling before and after testing?
• What are the costs involved, and are they covered by any package?

Next Steps

1. Review your medical and family history with your fertility specialist.
2. Ask for a referral to a genetic counselor if you are considering PGT-M or PGT-SR.
3. Discuss the potential benefits and limitations of each test in your specific case.
4. Make an informed decision based on your values and medical advice.

For more information about PGT in Thailand, visit our PGT in Thailand page. You can also explore our guides and FAQ sections for additional insights.

Frequently asked questions

Can PGT-A detect all genetic disorders?

No, PGT-A only screens for an abnormal number of chromosomes. It does not detect single-gene disorders or structural rearrangements. Other tests like PGT-M and PGT-SR are needed for those conditions.

Is PGT-M only for couples with a known genetic disease?

Yes, PGT-M is typically used when there is a known single-gene disorder in the family. It requires prior genetic testing of the parents to identify the specific mutation.

What is the difference between PGT-A and PGT-SR?

PGT-A checks for an abnormal number of chromosomes, while PGT-SR checks for structural rearrangements like translocations or inversions. PGT-SR is used when a parent has a known chromosomal rearrangement.

Is PGT mandatory for all IVF patients?

No, PGT is not mandatory. It is an optional test that may be recommended based on your medical history, age, or family history. Discuss with your clinic whether it is appropriate for you.

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.