If you are going through IVF, you have probably encountered the phrase "PGT," and possibly seen several versions of it: PGT-A, PGT-M, PGT-SR. These are distinct types of preimplantation genetic testing, each designed to screen embryos for a different category of genetic concern before transfer. They are not interchangeable, and knowing which applies to your situation is an important part of informed IVF planning.
This article explains what each type of PGT does, who it is typically recommended for, and how these tests fit into the broader picture of individualized fertility care at Hanabusa IVF.
What Is Preimplantation Genetic Testing?
Preimplantation genetic testing refers to the process of biopsying cells from an embryo, typically at the blastocyst stage on day 5 or 6 of development, and analyzing those cells for genetic characteristics before the embryo is transferred to the uterus. The goal is to select embryos most likely to implant successfully and result in a healthy pregnancy.
All three types of PGT require a blastocyst biopsy performed in the embryology lab. The biopsied cells are sent to an external genetic testing laboratory, and results typically return within five to ten business days. During that time, embryos are cryopreserved and await results before any transfer decisions are made.
PGT-A: Preimplantation Genetic Testing for Aneuploidy
What It Tests
PGT-A screens embryos for chromosomal abnormalities, specifically, whether each embryo has the correct number of chromosomes (46 in humans). An embryo with too many or too few chromosomes is called aneuploid. Aneuploid embryos are the leading cause of failed implantation and early pregnancy loss in IVF.
Who It Is Typically For
PGT-A is most commonly considered for patients over 35, patients with recurrent implantation failure or recurrent pregnancy loss, patients with prior IVF cycles that produced poor embryo quality, and those who simply want the highest confidence that the embryo being transferred is chromosomally normal before proceeding.
What It Reveals
PGT-A results classify embryos as euploid (chromosomally normal), aneuploid (chromosomally abnormal), or mosaic (a mix of normal and abnormal cells). Euploid embryos have a significantly higher implantation and live birth rate per transfer than untested embryos, particularly for older patients.
"PGT-A is a tool, not a requirement. For some patients, it provides meaningful reassurance and reduces the risk of a failed transfer. For others, particularly those with fewer embryos or at younger ages, the calculus is different. We discuss this decision individually with every patient."
— Dr. Lyndon Chang, Medical Director at Hanabusa IVF
PGT-M: Preimplantation Genetic Testing for Monogenic Disorders
What It Tests
PGT-M screens embryos for a specific, known genetic mutation that one or both parents carry. Unlike PGT-A, which looks at chromosome number, PGT-M is a highly targeted test designed for families at risk of passing on a specific inherited disease.
Who It Is For
PGT-M is recommended when one or both partners are carriers or are affected by a single-gene disorder, conditions such as cystic fibrosis, sickle cell disease, Huntington's disease, spinal muscular atrophy, BRCA mutations, and many others. It can also be used for HLA matching in cases where an existing child needs a stem cell transplant from a sibling donor.
What It Involves
PGT-M requires significant preparation before the IVF cycle begins. The testing laboratory must design a probe specific to your mutation, a process that typically takes four to eight weeks. This means PGT-M planning starts well in advance of the retrieval cycle. The result identifies which embryos have inherited the mutation and which have not.
PGT-SR: Preimplantation Genetic Testing for Structural Rearrangements
What It Tests
PGT-SR tests embryos for chromosomal structural abnormalities, specifically, translocations, inversions, and other rearrangements of chromosomal material. These structural changes can be inherited from a parent who carries the rearrangement in a balanced form but who may pass on an unbalanced form to embryos, causing developmental problems or recurrent pregnancy loss.
Who It Is For
PGT-SR is recommended for patients who have been identified, usually through a blood karyotype, as carrying a chromosomal structural rearrangement. Couples where one partner carries a balanced translocation often experience recurrent miscarriage because many of their embryos inherit the unbalanced form. PGT-SR identifies which embryos carry the balanced or normal arrangement and are suitable for transfer.
Can These Tests Be Combined?
Yes. In some cases, multiple types of PGT are appropriate. A patient carrying a BRCA mutation who is also 40 years old might choose both PGT-M (to screen for BRCA) and PGT-A (to screen for chromosomal abnormalities) simultaneously. At Hanabusa IVF, the decision about which type of preimplantation genetic testing to pursue, if any, is made after a thorough discussion of your history, family history, age, and what information the testing would provide.
"The question I ask patients is always: what decision would this test help you make? If PGT-A would change whether or how you proceed with a transfer, it may be worth doing. If it would not change anything, that is also a valid reason not to pursue it. The test should serve the patient's decision-making, not the other way around."
— Dr. Diana LeBlanc, a Fertility Specialist at Hanabusa IVF
Limitations of Preimplantation Genetic Testing
PGT is a powerful tool, but it has limitations worth understanding. Embryo biopsy carries a small risk of damage to the embryo. PGT-A results are based on a small number of cells sampled from the outer layer of the blastocyst and may not perfectly reflect the genetic composition of every cell in the embryo. PGT also cannot screen for every possible genetic condition; it tests for what it is specifically designed to detect. Hanabusa IVF works with Gattaca, a specialized PGT-A testing provider, to ensure rigorous testing standards and result interpretation.
Frequently Asked Questions
What is the difference between PGT-A and PGT-M?
PGT-A screens all embryos for chromosomal number (aneuploidy), which is relevant for most IVF patients. PGT-M screens for a specific, known genetic mutation in the family — it requires preparation before the cycle and is used when parents carry a heritable single-gene disorder.
Do I need PGT-A if I am under 35?
PGT-A is not required for younger patients, and the benefit is more modest than for older patients because chromosomal abnormality rates in eggs are lower. The decision depends on your history, embryo count, and goals. Your physician at Hanabusa IVF can help you weigh the benefits and trade-offs for your situation.
How long does PGT take?
PGT-A results typically return within five to ten business days after biopsy. PGT-M requires four to eight weeks of preparation before the retrieval cycle begins. Embryos are cryopreserved during the waiting period.
Can PGT guarantee a healthy baby?
No. PGT screens for specific genetic categories but cannot detect every possible condition. A euploid embryo has a higher likelihood of implanting and resulting in a healthy pregnancy, but it does not guarantee a live birth or the absence of conditions not covered by the test.
Who is PGT-SR for?
PGT-SR is for patients who carry a chromosomal structural rearrangement, such as a balanced translocation, identified through a blood karyotype. It helps identify which embryos carry the balanced or normal chromosome arrangement and are suitable for transfer.
Genetic Testing as One Part of Individualized Care
Preimplantation genetic testing is one of the most clinically powerful tools available in IVF, but it is most valuable when it is chosen thoughtfully, for the right reasons, in the right patient. At Hanabusa IVF, the decision about whether and which type of PGT to pursue is part of a broader, individualized conversation about your goals, your history, and what information will actually help you make better decisions. If you are wondering whether genetic testing is right for your IVF cycle, a consultation at Hanabusa IVF is the right place to work through that question.
