Learn More About Genetics & Fertility
Genetic Testing & Counseling
Planning to start a family involves many decisions. Carrier screening and Preimplantation Genetic Testing (PGT) are tools that can provide important information and allow you to make the most informed choices.
Gentic Carrier screening
Genetic Carrier Screening
When you are pregnant or planning to become pregnant, you want everything to go right. While most babies are born healthy, with every pregnancy, there is a small chance of having a baby with a genetic disorder. Carrier screening provides specific information about your genes, your partner’s genes, and your potential risk for passing on an inherited disorder to your child.For people who know they are at an increased risk of passing on a specific genetic condition, PGT-M or preimplantation genetic testing for monogenic/single gene defects can be performed before pregnancy to reduce the risk of having an affected child greatly.
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What is Genetic Carrier Screening?
At IHR, we are strong advocates of pre-conception genetic screening (also called carrier screening) to our patients as part of our routine pre-conception counseling. Its benefit to patients and their future children is immeasurable! At a minimum, every female patient is requested to complete genetic screening, through a blood test. To reduce costs, if not covered by insurance, we only ask for the male partner to be tested if the female’s test returns positive as a carrier for any genetic diseases. We test the male to ensure he is not a carrier of the same genetic diseases. If a genetic disease is found, the couple has the option to use in vitro fertilization (IVF) with preimplantation genetic testing for monogenic disorders (PTG-M) to avoid passing that disease onto their offspring. Couples who choose not to undergo pre-conception genetic screening are asked to sign a form declining testing.
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Genetic screening tests gene mutations that fall into each of these three categories:
- Those mutations that are common in a certain ethnic group
- Recessive mutations (dominant genes often show symptoms and are typically known already)
- Those mutations that have some likelihood of causing serious disease in affected offspring. Even if you’re healthy and have never had a family member affected by these diseases, you could be a carrier of a genetic mutation(s), which can put your future children at risk. This makes screening all the more important.
The Potential Results
POSITIVE
A positive result means that a disease-causing variant was found, and you are a carrier of one or more of the disorders tested. Being a carrier typically does not affect your own health; however, it does mean that there is an increased risk of having a child with that disorder. The next step is usually to test your partner. Genetic counselors are also available to discuss your specific risks and concerns.
NEGATIVE
A negative result means that no disease-causing variants were identified for any of the disorders tested. A negative test provides reassurance because the chance of you having a child with any of the tested disorders is reduced. However, no test can detect all carriers, so there is still a small chance, called a residual risk, of being a carrier. Genetic counselors are available to discuss your specific risks and concerns.
Preimplantation Genetic Testing (PGT)
What is Preimplantation Genetic Testing (PGT)?
Preimplantation genetic diagnosis (PGT) is an advanced genetic test performed before pregnancy. Embryos obtained by IVF are tested for chromosomal abnormalities or a known genetic mutation. Only the unaffected ones are transferred into the uterus for the woman to conceive a healthy baby. We can look for things like cystic fibrosis, thalassemia, Tay-Sachs disease, sickle cell disease, and over two hundred other genetic diseases.
Genetic Counseling is provided by our strategic partners at Igenomix and Sema 4.
When is Preimplantation Genetic Testing Used?
PGT is used when chromosome abnormalities (aneuploidies) are associated with failed implantation, pregnancy loss, and the birth of children with multiple congenital anomalies. PGT provides a means of testing for these chromosome abnormalities and selecting the best embryos for transfer. Embryos with chromosome abnormalities are physically indistinguishable from healthy embryos; therefore, without PGT, abnormal embryos are equally likely to be transferred, reducing the chances of achieving a viable and healthy pregnancy.
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The Four Different Kinds Of PGT Procedures:
PGT-A: Aneuploidy, formerly called PGS. ( This is a general screen)
PGT-M for Monogenic disorders. (This looks for specific disorders that you and your partner are carriers of)
PGT-HLA for matching. (This looks for an HLA match for an affected child you already have)
PGT-SR structural, formerly translocations. (If you or your partner have chromosomes that are translocated, this test will look for embryos whose chromosomes balanced translocations, meaning they are compatible with life)
How PGT is Different From IVF?
In this type of cycle, the monitoring and retrieval are the same for you as in a regular IVF cycle as well as fertilization. However, after the retrieval, besides beginning the antibiotics, your cycle is complete. In the IVF lab, the embryologist will culture the embryos for 5-7 days and keep you updated on their progress. If you choose, all embryos that make it to the blastocyst stage are biopsied for testing and the embryos are then frozen. All biopsies will be sent to RGI for genetic testing. Therefore, there is no transfer at this time.
You should expect your period to begin 5—14 days after the retrieval. With this period, you are encouraged to come in for morning monitoring for a new baseline ultrasound and blood tests to either begin a Frozen Embryo Transfer (FET) cycle or to begin another fresh IVF cycle if you are trying to generate more embryos.
How You Can Prepare For PGT
Unless otherwise directed by your insurance, at IHR, we use RGI (Reproductive Genetic Innovations) for all our embryo testing. A consult with a genetic counselor at RGI is required if you are considering or need the embryos to be tested. They will consult with you regarding PGT expectations and will also have their own consent for you to sign. The consultation may take place either in person in their office in Northbrook or via the phone.
If you are doing PGT-M for a specific disorder, you must reach out to them as soon as you can as they will need time to prepare their probes to specifically tailor to your needs. Depending on the disease, the setup of these probes can take up to 6 weeks to complete. The IVF cycle cannot begin until the setup is complete. If you are planning on doing PGT-A only, then there is no setup required and no delay in getting started with your IVF cycle.
Do you have any other questions about PGT? Connect With Us.
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