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Preimplantation genetic testing (PGT) is a reproductive technology comprised of three DNA based tests used in concert with in vitro fertilization (IVF) cycles to increase the potential for a healthy and successful pregnancy and delivery. PGT also allows the option for couples wanting to know the sex of their embryos before transfer to uterus.
Indications for the use of PGT cover a wide range of reproductive issues falling into three general categories: (1) to determine that an embryo has the correct chromosomal content prior to transfer, avoiding embryos with chromosomal gains, or losses called aneuploidy, (2) to detect inherited single-gene disorders, or (3) to identify structural chromosome rearrangements and/or unbalanced translocations.
Women of advanced reproductive age (over 38 years of age).
Couples with a history of recurrent unexplained miscarriages.
Couples who have experienced several failed IVF cycles.
Partners who are carriers of balanced structural chromosome rearrangements called balanced translocations.
Partners who are carriers of single-gene disorders like Huntington's disease or cystic fibrosis.
Partners with certain types of sperm abnormalities including low motility, low sperm count, and/or severe male factor infertility.
In vitro fertilization (IVF) is the most widely used method of assisted reproductive technology (ART) and combined with PGT (formerly PGS) can significantly increase the likelihood of a successful pregnancy. Using IVF, embryos are created and grown in the laboratory for 5 to 6 days until they form an early embryo called a blastocyst. The blastocyst embryos are subsequently biopsied to remove a few cells from the outer shell called the trophectoderm, and these cells are sent to Fairfax Diagnostics for DNA extraction and genetic analysis using PGT. PGT uses a method called Next Generation Sequencing (NGS). This technology determines the amount of DNA present for each chromosome in cells removed from the developing embryo. Gains or losses of complete chromosomes or parts of chromosomes are identified by NGS and a dedicated software algorithm. For sex determination, NGS testing can determine the presence of the sex chromosomes, XX or XY, for females or males respectively.
Organized in the form of a blog, this short and concise overview by ASRM, with illustrations, provides the general reader and couples considering PGT with an easily digestible introduction to the process.
Preimplantation genetic testing (PGT) is a reproductive technology comprised of three genomic assays used in concert with in vitro fertilization (IVF) cycles to increase the potential for a healthy and successful pregnancy and delivery. The suite of PGT assays is used (1) to determine that an embryo has the correct chromosomal content prior to transfer, avoiding embryos with chromosomal gains or losses called aneuploidy, (2) to detect inherited single-gene disorders, or (3) to detect structural chromosome rearrangements and/or unbalanced translocations.
PGT for monogenic disorders (PGT-M) is a reproductive technology used with an IVF cycle for at-risk couples to determine that an embryo used for transfer does not contain an inherited genetic disorder, thus ensuring that the disorder is not passed on to children. PGT-M is performed with PGT for Aneuploidy (PGT-A) to select embryos for transfer that are free of genetic disease as well as chromosomally normal (euploid).
PGT for aneuploidy (PGT-A) determines if an embryo has the correct number of chromosomes prior to implantation in the uterus. Chromosomes are structures within cells that contain the genetic material called DNA which is important for healthy development. For couples undergoing IVF, PGT-A can significantly increase the chance of a pregnancy and birth of a healthy child by transferring only chromosomally normal embryos.
PGT for structural rearrangements (PGT-SR) is a reproductive technology used with an IVF cycle for couples that carry chromosomal structural rearrangements (translocations). PGT-SR can identify embryos for transfer that contain balanced chromosomal content thus avoiding pregnancies carrying a severe chromosomal abnormality.
Looking for more information on PGT at Fairfax Diagnostics? Here are some frequently asked questions.
For couples pursuing testing for aneuploidy (PGT-A) and structural chromosome rearrangements (PGT-SR), a method called Next Generation Sequencing (NGS) is used. This technology determines the amount of DNA present for each chromosome in cells removed from the developing embryo. Gains or losses of complete chromosomes or parts of chromosomes are identified by NGS and a dedicated software algorithm. For gender determination, NGS testing can determine the presence the sex chromosomes, XX or XY, for females or males respectively.
Embryos created using standard IVF protocols with intracytoplasmic sperm injection (ICSI) are grown in the laboratory for 5 to 6 days until they form an early embryo called a blastocyst. The embryo is subsequently biopsied to remove a few cells from the outer layer, also called a trophectoderm, which is destined to form the placenta.
After biopsy, embryos are frozen and stored while the cell’s genetic material is tested for abnormalities using PGT. After PGT analysis, results are evaluated by the medical and genetics teams, then a Fairfax Diagnostics genetic counselor will discuss results with the patient/couple and a frozen embryo transfer (FET) cycle is planned for the healthy embryo(s).
Yes. Substantial data indicates that PGT does not increase birth defects over that of the general population. Removal of a few cells from the outer layer (trophectoderm) does not alter the ability of that embryo to develop a normal pregnancy; in fact, biopsy avoids disrupting the embryo’s inner most cells that will form the fetus. In embryos undergoing PGT testing, many fewer pregnancies will end in miscarriages due to chromosomal disorders since abnormalities are identified prior to embryo transfer.
Fairfax Diagnostics requires counseling for all PGT-M and SR patients. Also, we recommend consultation for PGT-A, if necessary.
Due to the complexity of testing for these genetic disorders, patients should have a full consultation with a medical geneticist or genetic counselor to determine if this option would fit their family’s needs. To schedule a telephone consultation, click the link below.
Contact us directly at 703-289-1860, email us at info@fairfaxdiagnostics.com, or click the contact us link below.
To get started with PGT at Fairfax Diagnostics contact us today.