Genetic, Pregnancy Screening Tests for Baby and You
The number of conditions that can be detected in genetic screening is increasing. But which tests should you get?
“When I discovered that I was pregnant with Margot, I was overcome with happiness to know that our family would be growing again,” says Rebecca Weiss of Huntingdon Valley, PA.
Genetic counseling wasn’t even suggested six years ago when her first daughter was born; it wasn’t offered two years ago when her son was born either. “But then magically when I hit 35, all of the sudden, they were bringing up genetic counseling and screening,” says Weiss.
Genetic testing field grows quickly
Part of the reason, in addition to her age, is that genetic testing has advanced so quickly.
“Since screening is changing yearly, it can be overwhelming for patients to even know which tests are offered,” explains Erica Schindewolf, a genetic counselor at the Center for Fetal Diagnosis and Treatment at Children’s Hospital of Philadelphia. “If you were pregnant before, you might think you know, but there could be another option that came into the pipeline.”
Despite the increase in the number of genetic tests, it’s important to remember that the chance your baby will have a birth defect is usually 3 to 5 percent, says Zohra Ali-Khan Catts, director of cancer genetic counseling at Christiana Care Health System’s Helen F. Graham Cancer Center & Research Institute in Newark, DE.
Cost for tests continue to fall
Advancements in technology have led to more accurate testing for specific genetic conditions, at a reduced cost and with quicker results, says Lama Elkhoury, director of genetic counseling services at Sema4, a genetic-testing venture of Mount Sinai Health System, based in Stamford, Conn.
“Five or six years ago, to sequence just one gene could cost about $2,000 and take six-to-eight weeks to get the results back,” she says. “Now we can sequence hundreds of genes in carrier screening panels, with rapid turnaround time and at more affordable rates due to decreased sequencing costs.”
Despite the reduced costs, the decision to be tested sometimes depends on whether the family’s health-care coverage will pay for it.
“Often genetic testing is driven by the patient’s preference and insurance provider,” says Schindewolf.
Ideally, the best time to review your family’s health history is before you are pregnant.
A genetic screening determines if you and your partner are carriers for some of the most common genetic conditions that may affect the outcome of pregnancies and the likelihood of passing the mutation to your baby, explains Schidewolf. Many families mistakenly believe a genetic screening can check for all genetic conditions.
“It doesn’t, it only screens for 100 or 200 very selective conditions, but it’s definitely a good baseline risk assessment,” says Schindewolf, especially if you are part of a population that has a high frequency for some diseases, such as TaySachs among those of Ashkenazi Jewish descent.
‘Maybe we should slow down’
While it is possible to be screened for hundreds of conditions, should you?
Richard Fischer, MD, division head of maternal-fetal medicine at Cooper University Hospital of NJ, follows the recommendations of the American College of Obstetricians and Gynecologists, which suggests screening for the most commonly tested genetic conditions: cystic fibrosis, hemoglobinopathies, such as sickle-cell disease, and spinal muscular atrophy.
“The concern is that one lab tries to outdo the other by saying they have more tests, more screening, more detection, when the process has not been standardized,” Fischer says. “We are relying on the claims of these commercial companies to be the newest and the greatest.”
Screening may not be accurate for some rare diseases, he notes, which could cause patient anxiety, especially because the fetus cannot be tested to check for some conditions.
“Maybe we should slow down and just do the standard tests, unless there’s something in the family or a certain ethnic background that suggest you are at higher risk,” he says.
Once you are pregnant, testing can be done on the fetus for certain conditions. The Sequential screen that uses a blood test and ultrasound, done between 11 and 14 weeks and 16 to 18 weeks, detects about 99 percent of Down syndrome cases with a 3.5 percent false-positive rate, says Fishcer, and can detect about half of other chromosomal abnormalities.
The Non-Invasive Prenatal Test (NIPT) is also offered to all expectant moms but is recommended for women 35 and older because the risk of a chromosome abnormality is higher and the results are more accurate.
NIPT is the most sensitive screening option for Down syndrome, trisomy13, trisomy18, says Ali-Khan Catts. “A positive result means the baby has a higher chance to have the condition and a diagnostic test such as amniocentesis or chorionic villus sampling is recommended to determine if the baby has the condition. ”
Each state has its own set of tests it requires for newborns.
Pennsylvania tests for 38 genetic conditions and the results can sometimes be life saving.
Gerard A. Margiotti, Jr., MD, of Margiotti & Kroll Pediatrics, in Philadelphia and Bucks County, recalls when he got a call from the state at 10pm on a Saturday night.
“One of their tests was positive on a baby, and we were able to send the baby to CHOP,” he says. “The baby was treated and ended up being normal instead of having suffered risk of a serious reaction or death.”
You can find out what tests are required in Pennsylvania, New Jersey and Delaware at Babysfirsttest.org.
Lynda Dell is a Pennsylvania-based freelance writer.