Non-invasive prenatal genetic screening: an interview with Dr. Charles Strom, Senior Medical Director, Quest Diagnostics
What syndromes can be screened for using non-invasive prenatal genetic testing?
A new category of non-invasive genetic screening tests is gaining a great deal of interest in the medical field – including from Quest Diagnostics — for its potential to help screen women during pregnancy for genetic abnormalities known as trisomies, the most common of which is Down syndrome.
This new category of blood tests evaluates cell-free fetal DNA in circulating maternal blood. Quest Diagnostics, which is a leader in genetic and women’s health diagnostics, is very interested in this field and recently announced it will soon offer access to a test called Panorama, which was developed by Natera.
The Panorama test can help physicians screen for chromosomal abnormalities associated with trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome) as well as monosomy X (Turner syndrome).
How prevalent are these syndromes?
The most recent data from the U.S. Centers for Disease Control and Prevention indicate that about 6,000 diagnoses of Down syndrome are made in the United States every year, making it the most common genetic condition.
While Edwards syndrome, Patau syndrome and Turner syndrome are far less common, they can cause significant forms of disability.
Please can you outline how prenatal genetic tests have traditionally been carried out?
Since the 1960s, pregnant women have been offered the option of screening or testing for Down syndrome and other trisomies. Both amniocentesis and chorionic villus sampling (CVS) are medical procedures which require insertion of a needle into the amniotic sac to extract fluid (amnio) or a small amount of tissue (CVS). The tests are highly accurate, but they both carry a slight risk of risk of miscarriage.
For the past 20 years women had the option of having a screening test called maternal serum screening, initially in the second trimester and now in the first trimester or both. These screening tests had a low specificity with only about 5% of pregnancies with high risk results being affected with a trisomy. Their sensitivity was only about 80%.
In December 2012, the American Congress of Obstetricians and Gynecologists (ACOG) issued a medical opinion stating that cell-free fetal DNA testing is one option that can be used as a primary screening test in women at increased risk of aneuploidy (abnormal numbers of chromosomes). It may also be offered as a follow-up test for women with a positive first-trimester or second-trimester screening test result.
What risks do invasive prenatal genetic tests pose?
Invasive prenatal tests such as amniocentesis and CVS are associated with a small risk of miscarriage, estimated to be between 1-2% for CVS, and 0.5% for amniocentesis.
While these numbers sound small, as many as 800,000 women may be considered high-risk under the ACOG guidelines and therefore possible candidates for these invasive procedures each year.
A “low risk” test result from Panorama may help some women, in consultation with their physician, to consider forgoing invasive procedures. In this way, Panorama may help promote healthy pregnancies.
Please can you give an introduction to the new non-invasive prenatal test Panorama™?
Panorama is a test developed by Natera that uses cell-free fetal DNA in circulating maternal blood to screen for chromosomal abnormalities associated with trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), trisomy 13 (Patau syndrome) and monosomy X (Turner syndrome). Panorama can be used as early as the ninth week of pregnancy.
Panorama is a lab-developed test that was developed, validated and is now offered by Natera’s CLIA-certified laboratory in San Carlos, Calif. Quest Diagnostics will begin to offer physicians access to Panorama™ in certain regions of the United States in March and nationwide in April 2013, and physician clients of Quest Diagnostics will be able to forward specimens for testing to Natera’s lab. We are excited to bring this innovative technology to our physician clients and women for whom Panorama may be considered an option.
What does a test result mean?
Panorama is a non-invasive screening test that provides early information for assessing pregnancy risks. A ‘low risk’ Panorama test result indicates a very low likelihood that a pregnancy is affected, although it cannot guarantee it is not.
Nonetheless, this information may help a woman consider, in consultation with her physician and results of other medical assessments, whether to pursue or forgo invasive diagnostic testing, which carries a slight risk of miscarriage.
What benefits does this test have over traditional invasive tests?
Panorama test results provide information to help a woman consider whether to pursue or forgo invasive diagnostic testing. This is potentially important to promoting a healthy pregnancy, because invasive procedures carry a slight risk of miscarriage. In this way, Panorama may promote healthy pregnancies.
Are there any limitations of Panorama™?
The non-invasive prenatal screening test market has many strong offerings, but we at Quest Diagnostics determined that Natera was the best option for our company and physician clients at this time.
Will Panorama™ replace the need for invasive prenatal tests?
Panorama is a non-invasive screening test, not a diagnostic test. Whether it replaces CVS or amniocentesis in a distant future remains to be seen. We are focused on the value of this technology today in promoting healthy pregnancies.
What impact do you think Panorama™ will have on prenatal testing?
We at Quest Diagnostics are proud to provide information services that can help women make decisions affecting their health, and Panorama is consistent with this goal. Cell-free fetal DNA tests have, very quickly, gained recognition from ACOG and other medical associations.
How do you think prenatal testing will develop in the future?
Tremendous advances are being made in genomic testing, including those associated with cell-free fetal DNA. By offering physicians and patients access to Panorama, Quest Diagnostics is delivering on its commitment to provide clinically important innovations aligned with guideline-based care, and we’ll continue to explore new technologies that can provide diagnostic information to promote good health.
What ethical issues does prenatal testing raise?
Panorama is a screening test to help a woman and her physician consider whether to forgo invasive diagnostic procedures that have a slight risk of miscarriage. In this way, it may help to promote healthy pregnancies.
What are Quest Diagnostics’ plans for the future?
We’ll continue to monitor the market and development of new technologies to ensure we are providing the finest prenatal diagnostics to patients and clinicians.
Diagnostic information services are vital to empowering better health, and we take seriously our commitment to helping women and all of our patients access the best technologies from which to make well-informed healthcare decisions.
By providing access to Panorama, we’re very proud to be delivering on our commitment to provide clinically important innovations aligned with guideline-based care.
About Dr Charles Strom
Charles M. (“Buck”) Strom, MD, PhD, FAAP, FACMG, HCLD, is senior medical director, genetics, for Quest Diagnostics Nichols Institute, the research and development center of Quest Diagnostics, the world’s leading provider of diagnostics information services.
In this role, Dr. Strom is responsible for research and development and medical consultations in the areas of cytogenetics, biochemical genetics and molecular genetics for Quest Diagnostics’ nationwide network of physician clients.
Dr. Strom’s research and development has resulted in new clinical testing methods (several of which are patented or patent pending) for cystic fibrosis, Fragile X and other genetic and developmental disorders.
Dr. Strom is board certified in clinical genetics, biochemical genetics and clinical molecular genetics. A sought-after speaker on genetics and developmental disorders, he has authored or participated in numerous studies published in peer-reviewed publications.
Dr. Strom received his medical degree with honors from the Pritzker School of Medicine, University of Chicago.