Learn more about the change in terminology from PGS/PGD to PGT-A/PGT-M
Patients who visit our Southern California fertility doctors are sometimes curious why there was a change from PGS/PGD to PGT-A/PGT-M. A common misconception is that these types of preimplantation genetic tests are now different, but that is not the case. The change in these terms just allows for a more accurate representation of what the tests do.
Until relatively recently, fertility specialists used the terms PGS, or preimplantation genetic screening, and PGD, or preimplantation genetic diagnosis, to describe the genetic testing of embryos. Now, PGS is PGT-A, or preimplantation genetic testing for aneuploidy, while PGD is PGT-M, or preimplantation genetic testing for monogenic/single gene defects.
Why fertility specialists went from PGS/PGD to PGT-A/PGT-M
Understanding why and how we use these types of preimplantation genetic testing provides more comprehensive insight into the change from PGS/PGD to PGT-A/PGT-M. Each test can play an important role in helping our patients conceive a healthy baby.
PGT-A, formerly PGS, is how we determine whether an embryo is aneuploid (having too few or too many chromosomes). Aneuploidy can cause miscarriage, embryo implantation failure or chromosomal disorders like Down syndrome. The name for this test now includes the term “aneuploidy” because that’s what it tests for.
PGT-M, formerly PGD, screens embryos for genetic defects involving a single gene, like cystic fibrosis. The name for this test now includes the term “monogenic/single gene defects,” as that’s what it tests for.
We hope these new terms make it easier for patients to understand the purpose of each test.
The ideal candidates for PGT-A and PGT-M
PGT-A and PGT-M can help fertility specialists ensure they only transfer genetically normal embryos. However, some patients are better candidates for PGT-A, and others for PGT-M.
Who needs PGT-A? A woman can benefit from PGT-A if she is over age 35 and free of inheritable genetic issues. The woman should also have a partner with no known inheritable genetic disorders or should be using a healthy sperm donor. PGT-A is also helpful for women who have experienced recurrent miscarriages or unsuccessful IVF cycles.
Who needs PGT-M? Women and men with known inheritable genetic disorders, like cystic fibrosis or sickle cell disease, should likely utilize PGT-M. This test allows the embryologist to test the embryos for whatever disorder the patients carry.
Our Southern California fertility doctors help patients understand the purpose of the two types of preimplantation genetic testing. They can also help hopeful parents determine which test might give them the best chance of taking home a healthy baby. Contact us for more information about the shift from PGS/PGD to PGT-A/PGT-M.