How Genetic Testing at PREG Can Shed New Light on Your Fertility Journey
The idea of pregnancy alone can bring on a swirl of emotion with so much focus on what the future might hold. But pregnancy itself—not to mention the challenges that many women face in becoming pregnant—can be a fraught experience, full of mysteries to be unwound.
So it’s not unusual for prospective parents to want to take a deeper look at what’s going on inside their bodies through tests that are becoming a more routine part of the fertility process with every passing year.
Genetic testing can help determine whether a prospective parent carries the mutation for a certain genetic disorder that may be passed on to the child. When performed as part of in vitro fertilization (IVF), it can help determine which of a woman’s embryos have the best chance of resulting in a successful pregnancy. It can help determine why women are losing repeated pregnancies, why they’re entering menopause early, and also help figure out the reason behind male infertility.
All of those tests are conducted at Piedmont Reproductive Endocrinology Group, a fertility practice located in the Nexton area of Summerville. “There are many reasons we see patients. Sometimes it’s not difficult to get pregnant, but it’s difficult staying pregnant. We’re here to help explain some of that,” says Dr. Edward Tarnawa, medical director at PREG Lowcountry, which recently relocated from Mount Pleasant to Nexton, where he performs comprehensive fertility evaluation and treatment along with his associate, Dr. Kathryn Snow.
“In the old days, that was easier said than done because the price was prohibitive. We can now screen for several hundred conditions in a single blood test. In the majority of cases, insurance will cover it without issue. Even when it's out of pocket, the testing, depending on the platform that you use, typically won't exceed $400 for both members of a couple, making it accessible, and patients need to be aware of it.”
Carrier risks can depend on ancestry
Some genetic disorders can be passed down from parents to their children. According to the American College of Obstetricians and Gynecologists, if both parents are carriers of a recessive gene for a disorder, there is a 25 percent chance that their child will inherit the mutation from each parent and will have the disorder. There is also a 50 percent chance the child will be a carrier of the disorder, as the parents are, although those risks can vary depending on ancestry.
Carrier screening, performed through a simple blood draw or cheek swab, can be conducted before a couple even begins the path toward pregnancy. Although carrier screening can check for hundreds of genetic disorders, cystic fibrosis—caused by a genetic mutation that changes a protein regulating the movement of salt in and out of cells—is among the most prominent.
“Cystic fibrosis is an extremely serious condition that in its usual form leads to severe pulmonary disease, often from young age, and it can lead to a shortened lifespan. The likelihood that someone is a carrier is a lot higher than most people think, depending to some extent on ancestry,” Dr. Tarnawa says. “It’s as common as one in 25 for individuals of some ethnicities, so it's recommended that all couples be aware of the availability of cystic fibrosis carrier screening.”
The results of carrier screening can lead to difficult conversations between couples, physicians, and counselors.
“I think it's best to talk about the scenarios before the testing is even performed,” Dr. Tarnawa says. “And that's something we take the time to do: talk with patients about the potential implications of the results. Whether they be clinical or moral/ethical, it's important to know with any type of medical testing why it’s being performed.”
Enhancing chances of pregnancy
There are also types of genetic screening specifically tailored to a fertility setting that help enhance a woman’s chances of becoming pregnant. PGT-A, preimplantation genetic testing for aneuploidy, is performed in the setting of IVF and involves eggs that are retrieved and fertilized in a laboratory setting. The eggs are cultured for several days at PREG’s on-site IVF lab. Resulting embryos that reach a stage called blastocyst—when the embryo is ready for implantation into the uterus—become the candidates for embryo transfer.
Once those embryos reach the transferable stage, the part that becomes the placenta can be biopsied. That biopsy indicates which embryos have the correct number of chromosomes and which do not. “It’s a way for us to avoid futile embryo transfers that will not lead to success,” Dr. Tarnawa says. “It leads to a much higher success rate on a per-embryo transfer basis and reduces the risk of conditions such as Down syndrome. It can also reveal the genetic sex of the embryos prior transfer, but doesn’t have to be disclosed if patients don’t wish to be made aware of this information.”
Another type of PGT test allows physicians to search for certain gene mutations that might place a child at risk for genetic disorders. “Among those embryos with the correct number of chromosomes, we can then identify the ones which harbor that pathogenic set of mutations,” Dr. Tarnawa says, “and then give the patient the clearest understanding of what they have to work with and what their reproductive risk status would be.”
PREG also offers tests that can explore the reason behind recurrent pregnancy loss, which can have a genetic component stemming from the way chromosomal material is packaged. There are also genetic tests for male factor infertility, which can save the male from other tests that can be risky and invasive. Additionally, there are tests to search for the cause of early menopause, which can have its root in genetic abnormalities, some of which can be passed down in a family, and potentially increase the risk of certain genetic conditions in children.
“It's a genetic world in which we live,” Dr. Tarnawa says. “This testing is available and it's important, but it requires time to go through the rationale for the testing—what it's looking for and how it can impact management. That takes time and patience. We devote the proper time to making sure that the patients are fully counseled about what we can offer and what they can do with the information.”
Interested in learning more about genetic testing options or other matters related to fertility? Contact PREG at (843) 881-7400, visit their website at PREGOnline.com, or visit their office at 5500 Front St., Suite 410, in Summerville. The largest fertility practice in the Carolinas, PREG also has comprehensive fertility/IVF centers in Columbia and Greenville as well as offices in Spartanburg and Asheville, NC.