Preimplantation Genetic Testing (PGT)
Preimplantation genetic testing (PGT) is an advanced procedure performed during in vitro fertilization (IVF) to carefully evaluate embryos for genetic or chromosomal abnormalities before implantation. This process helps increase the likelihood of having a healthy pregnancy. For many, PGT offers an added sense of reassurance and hope on their path to parenthood.
Types of Preimplantation Genetic Testing
There are different types of PGT, each designed to assess embryos for specific genetic or chromosomal abnormalities. These tests are also sometimes referred to as preimplantation genetic diagnosis (PGD) and preimplantation genetic screening (PGS). Each type of PGT serves a unique purpose and can provide valuable information to help guide the IVF process.
Preimplantation Genetic Testing for Monogenic/Single Gene Disorders (PGT-M)
Preimplantation genetic testing for monogenic/single gene disorders (PGT-M), formerly known as preimplantation genetic diagnosis (PGD), is used to identify embryos carrying specific genetic mutations or chromosomal abnormalities. PGT-M is often recommended for individuals or couples who are carriers of inherited genetic disorders or have a family history of certain conditions, helping them select the healthiest embryos for transfer.
To perform PGT-M, a single cell is biopsied from each viable embryo around day 5 of development. These cells are sent to a specialized genetics lab where they are screened for specific genetic mutations. While awaiting the results, the embryos are cryopreserved. Once results are available, the embryos identified as free of the targeted genetic conditions are prioritized for transfer, increasing the likelihood of a successful pregnancy and the birth of a healthy baby.
How Does PGT-M Improve Pregnancy Rates?
PGT-M improves pregnancy rates by detecting embryos affected by inherited genetic conditions before implantation. This early identification helps prevent the transfer of embryos that may result in failed implantation, miscarriage, or serious health issues after birth. PGT-M is commonly used to screen for conditions such as:
- Chromosomal Translocations: A rearrangement of chromosome parts, which can be balanced or unbalanced. Unbalanced translocations can lead to implantation failure, miscarriage, or physical and developmental disorders.
- Single-Gene Disorders: Conditions caused by mutations in a single gene. PGT-M can detect over 4,000 single-gene disorders, with common examples including cystic fibrosis, Tay-Sachs disease, fragile X syndrome, myotonic dystrophy, and thalassemia.
Who Can Benefit from PGT-M?
PGT-M may be recommended for individuals or couples who:
- Are known carriers of a single-gene genetic disorder
- Have a family history of a chromosomal condition such as Down syndrome, Turner syndrome, Klinefelter syndrome (XXY), or Edwards syndrome
- Are women over 35, as the risk of chromosomal abnormalities increases with age
- Have experienced recurrent miscarriages
- Have had a failed IVF cycle due to unexplained reasons
Preimplantation Genetic Testing for Aneuploidy (PGT-A)
Preimplantation genetic testing for aneuploidy (PGT-A), formerly known as preimplantation genetic screening (PGS), is used to assess embryos for chromosomal abnormalities before implantation. PGT-A helps identify embryos with the correct number of chromosomes, reducing the risk of miscarriage and implantation failure. This additional information allows the embryology team to select the healthiest embryos, increasing the likelihood of a successful pregnancy.
PGT-A is performed by biopsying one or two cells from each embryo around day 5 of development. These cells are analyzed in a specialized genetics lab to determine whether the embryo has the normal number of 46 chromosomes—23 contributed by each partner. Embryos with the correct number of chromosomes have the highest potential for implantation and healthy development.
How Does PGT-A Improve Pregnancy Rates?
PGT-A improves pregnancy rates by identifying embryos with aneuploidy, a condition where an embryo has too many or too few chromosomes. Aneuploidy is a leading cause of miscarriage, implantation failure, and genetic conditions. By screening for chromosomal abnormalities, PGT-A allows providers to transfer only chromosomally normal embryos, increasing the chances of a healthy pregnancy. Additionally, PGT-A supports the use of single embryo transfer (SET), minimizing the risk of complications associated with multiple pregnancies.
Who Can Benefit from PGT-A?
PGT-A may be recommended for individuals or couples who:
- Have experienced multiple unexplained miscarriages
- Are 35 or older, as the likelihood of chromosomal abnormalities increases with age
- Have had previous implantation failures during IVF
- Wish to reduce the risk of transferring an embryo with chromosomal abnormalities
Schedule a Consultation for PGS & PGD Genetic Screening
These diagnostic technologies can provide a much higher degree success for patients who fit the criteria, but determining which test to perform and when to perform it can be a difficult decision. We would love the opportunity to discuss PGD and PGS with you in person. We invite you to learn more about our fertility clinic locations in Austin, Dallas, Houston, McAllen, and San Antonio, get five-star patient support, or request an appointment to get started.
