Prenatal testing today
Many genetic testing options are available for pregnant women and their health care providers today. The purpose of these tests is to look for certain fetal health problems during pregnancy. Some tests are called “screening” tests and others are called “diagnostic” tests.
Traditional screening tests are used to predict the chance for a pregnancy to have certain chromosome conditions. These tests are not invasive; in that they involve a blood draw from the mother and sometimes an ultrasound. Some screening tests require more than one office visit to perform multiple blood draws and ultrasound examinations at very specific times in pregnancy. Results from many screening tests will provide a “risk score” (such as 1 in 500 or 1 in 50) that describes the chance of a fetus having trisomy 21 (Down syndrome). These risk scores can be confusing. A screening test may be “negative” (or low risk) in as many as 30% of pregnancies affected by one of these chromosome conditions. Also, a screening test will be “positive” (or increased risk) in about 5% (1 in 20) of women who have the test, even though most of these women have healthy pregnancies. This means a woman whose fetus has a chromosome problem may incorrectly receive a negative (or low risk) result, and a woman with a normal fetus may receive a positive (or high risk) result.
Screening tests can help women and their providers decide whether to have an invasive diagnostic procedure. It is generally recommended that patients receiving a “screen positive” result be offered an invasive diagnostic procedure to confirm if the fetus has a chromosome abnormality.
Diagnostic procedures, such as amniocentesis or chorionic villus sampling (CVS), can determine whether a fetus has trisomy 21 (Down syndrome), trisomy 18, or other chromosome conditions. The invasive nature of these procedures can give rise to concern among some patients.
verifi® prenatal test
In response to this need, Illumina is proud to offer the verifi® prenatal test, a non-invasive test that detects multiple fetal chromosomal aneuploidies. The test detects three primary chromosomal aneuploidies for trisomies 21, 18 and 13 from a single blood draw as early as 10 weeks estimated gestational age. Trisomies occur when three, instead of the usual two, copies of a chromosome are present.
In addition, Illumina also offers the sex chromosomes test option, which includes the detection of Turner syndrome (Monosomy X), Triple X (XXX), Klinefelter syndrome (XXY), and Jacobs syndrome (XYY), the most common fetal sex chromosome abnormalities (also called sex chromosome aneuploidies). Sex chromosome aneuploidies are conditions in which there is a change from the usual 2 copies of sex chromosomes in males (XY) or females (XX). All of these conditions may cause mental or physical disabilities, with different levels of severity.
This test is available for singleton and twin pregnancies.*
A sample of your blood is drawn and the genetic material is tested. This test uses a technology called “massively parallel DNA sequencing” to count the number of copies of these chromosomes, and then uses a calculation method to determine if there are too many or too few copies of these chromosomes present.
Indications for use
This screening test may be an option for you to consider if:
You have a confirmed singleton or twin pregnancy of at least 10 weeks gestational age, and meet any of the following criteria:
- You are considered to be of advanced maternal age (35 years or older [singleton pregnancy] or 32 years or older [twin pregnancy] at time of delivery)
- You have an abnormal or “positive” serum screen
- Your ultrasound shows concerns or abnormalities with fetal growth and/or development
- You have a personal or family history of chromosomal aneuploidies for trisomies 21, 18, 13, or other sex chromosome aneuploidies
Your test report will include one of three possible results for chromosomes 21, 18, and 13: No Aneuploidy Detected, Aneuploidy Detected, or Aneuploidy Suspected (Borderline Value). Sex chromosomes will be reported as No Aneuploidy Detected or Aneuploidy Detected. In the case of a twin pregnancy, Y chromosome presence will be reported as Detected or Not Detected.
- A No Aneuploidy Detected test result means that this test identified the expected number of copies of chromosomes reported
- An Aneuploidy Detected test result means that this test identified too many or too few copies of one of the chromosomes as seen on the report. This can indicate either a trisomy or a sex chromosome aneuploidy
- An Aneuploidy Suspected test result means that this test identified more copies than expected of the chromosomes reported. This means that your provider should follow up on this result to obtain more information
The verifi® prenatal test is a highly accurate advanced screening test that is non-invasive. Genetic counseling before and after testing is recommended. Results of “Aneuploidy Detected” or “Aneuploidy Suspected” are considered positive and patients should be offered invasive prenatal procedures for confirmation. A negative test does not ensure an unaffected pregnancy. Chorionic villus sampling and amniocentesis provide definitive diagnostic information, but are not without risks to you and your baby.
Illumina is excited to be at the forefront of improving noninvasive prenatal testing options with its proprietary technology to evaluate multiple fetal chromosomes across the genome. Founded with strong academic and scientific support from major medical and clinical research institutes, the company is committed to helping clinicians offer the latest in prenatal care to patients.
*The verifi® prenatal test for chromosomes 21, 18, and 13, is available for singleton and twin pregnancies. Sex chromosomes aneuploidy testing is available for singleton pregnancies only. An optional test for twin pregnancies tests for the presence of the Y chromosome.