What is Preimplantation Genetic Testing (PGT)
Intended parents choose to do IVF with preimplantation genetic testing (PGT) to substantially decrease the chance of having a child with a certain genetic or chromosomal condition. PGT (formerly PGD) can be used to identify embryos at risk of having a specific genetic or chromosomal condition.
During your PureOvum consult, you will be asked to consider and decide on any potential tests you’d like to have completed on your developing embryos. These tests can highlight several things from gender to the presence of any potential genetic disorders.
The American Congress of Obstetricians and Gynecologists (ACOG) recommends genetic testing when preparing for and managing a successful pregnancy.
Preimplantation Genetic Testing Overview
- Preimplantation genetic testing (PGT) of embryos has made tremendous advances since its introduction in 2005. Although genetic testing could be performed on human cells before 2005, techniques were developed to perform genetic testing on just a few cells removed from a developing embryo.
- Genetic testing allows prospective parent(s) undergoing in vitro fertilization (IVF) to test for a specific gene or chromosomal copy number abnormalities before transferring the embryo into the uterus. This can increase pregnancy rates and decrease miscarriage rates.
- Chromosomes are structures found in the center of the cell nucleus. A human typically has 23 pairs of chromosomes, for a total of 46 individual chromosomes. An embryo receives 23 chromosomes from the sperm and 23 from the egg. Chromosomes are made up of genes, which contain the genetic information that instructs the body on how to function.
- Embryos can be tested before an embryo transfer for their chromosomal copy number or rearrangement (preimplantation genetic testing – PGT) or a specific singe gene mutation (PGT-M).
- This testing is performed on cells from an embryo biopsy on the 5th or 6th day of embryo development. Embryos are frozen, or “banked,” until results of the genetic testing are available.
- Embryos that are identified to have the correct number of chromosomes (euploid) and/or do not carry the specific mutation tested for (“unaffected”) can then be transferred into the patient in a separate FET (frozen embryo transfer) cycle.
Would I Benefit from PGT During Egg Donor Treatment?
PureOvum is privileged to be physician-owned — in turn able to provide compassionate and professional clinical expertise. The Fertility Specialists Medical Group has performed PGT for a wide variety of inherited pediatric and adult-onset genetic conditions and chromosomal abnormalities using different genetic technologies and protocols.
PGT can be valuable for all hopeful parents using IVF to conceive and is especially useful and highly recommended for certain groups of patients, such as those with:
- Advanced maternal age (35 years or older)
- Previous IVF failure
- A previous child with a genetic condition
- A history of recurrent miscarriages
- Unexplained infertility
- Family history of genetic disease
The availability of in-house genetic fertility specialists is a unique aspect of our West Coast egg donor program — as they help our patients understand their genetic risks and options and interface with the laboratory while accompanying patients on their journey to parenthood via IVF and egg donation.
PGT (Preimplantation Genetic Testing) is available for most serious genetic conditions if the gene mutation or chromosomal condition in the family has been identified through genetic testing.
If you are found to have an increased risk of having a child with a genetic condition, our fertility specialists recommend IVF with one or more types of preimplantation genetic testing.
- PGT-A: Preimplantation genetic testing for aneuploidy. PGT-A examines the 23 pairs of chromosomes within individual cells from each embryo. Embryos with the typical number of chromosomes are called euploid and most likely will result in a successful pregnancy. Those with ab-normal chromosome composition are called aneuploid and most likely will either not implant or result in a baby with a genetic condition.
- PGT-M: Preimplantation genetic testing for monogenic/single-gene defects. Rather than counting chromosomes in cells taken from embryos, as with PGT-A, PGT-M explores specific genes, searching for a specific genetic defect that is known to run in your family or for which you or your partner is known to be a carrier.
- PGT-SR: Preimplantation genetic testing for chromosomal structural rearrangements. Combined with PGT-A, PGT-SR tests your embryos for specific structural changes for which you and/or your partner are at risk. Such rearrangements can hinder the chance of implantation, increase miscarriage rates or the chance of birthing a baby with a chromosome disorder.
These conditions are caused by DNA mutations in a single gene.
Some examples of single-gene conditions for which PGT can be done are:
- Pediatric conditions such as cystic fibrosis, spinal muscular atrophy, thalassemia, and sickle cell anemia
- Metabolic disorders such as Tay-Sachs disease and Fanconi anemia
- Hereditary cancer syndromes such as breast/ovarian cancer predisposition (known to be associated with BRCA1 or BRCA2 genes), Lynch syndrome, and hereditary diffuse gastric cancer
- Inherited neurologic and muscular conditions such as Huntington’s disease, spinocerebellar ataxia, frontotemporal dementia, muscular dystrophy, and myotonic dystrophy
- X-linked conditions such as Fragile X syndrome, hemophilia, adrenoleukodystrophy, and Duchenne muscular dystrophy
- Inherited heart disease such as hypertrophic or dilated cardiomyopathy, long QT syndrome, and other arrhythmias; autosomal recessives, autosomal dominant, and X-linked genetic disorders