In the past 10 years, there has been copious amounts of genetic research. In fact, when I worked in the Massachusetts Legislature, I assisted in the amendment of a law (M.G.L. Chapter 151B), to provide genetic protections for individuals since genetics would be playing a large role in medical care in the decades ahead. One area that genetic testing is playing a new role, is in pre-natal care.
With my background in health care, as well as being pregnant, I have done a lot of research recently on a newly public non-invasive DNA test that screens for three common fetal abnormalities. These abnormalities are often referenced as T21 (Down Syndrome), T18 (Edwards Syndrome) and T13 (Patau Syndrome). This new test is currently offered as an alternative to amniocentesis for patients who screen positive for a risk of Down Syndrome or the other two chromosomal abnormalities.
The information on the test is primarily found on medical websites, which can be often hard to understand through all the medical jargon, and mis-information is often found on pregnancy forum boards. So after an interview with a genetic counselor who was part of the study, a review of the medical literature, public press releases and articles, I will do my best to help anyone reading this to get some generally accurate information that is in one place and (hopefully) easier to read.
What is it?
In the fall of 2011, a company called The Sequenom Center for Molecular Medicine® (Sequenom) published a peer review study showcasing the use of a noninvasive blood test to detect and analyze the DNA in pregnant women. Rather than harvesting placental tissue cells as is required for chorionic villus sampling (CVS), or entering the uterus to sample the amniotic fluid surrounding the baby (as is done with amniocentesis), circulating DNA can be obtained from maternal blood. Since it is just a maternal blood draw, there is no fetal risk as associated with amniocentesis or CVS.
What does it test?
The MaterniT21 test is currently known for testing for the T21 chromosome – the chromosome known to be associated with Down Syndrome. However, according to a press release issued by the company on January 8, 2012, Sequenom stated “In addition, the study results determining the accuracy of the MaterniT21 in detecting two additional fetal abnormalities, Trisomy 18 and Trisomy 13, are scheduled to be published in a peer review journal during the first quarter of this year.” So despite the name MaterniT21, the DNA test does scan for T18 and T13 chromosomes as well.
How long has it been available?
Some are concerned that the published Fall 2011 study only had a small sample group (212 women). However, it was just a part of a study. The testing has been done since the late 1990s, but it was not made available to the overall general public because the cost of the test (from collection and transfer to analysis and reporting) was so high ($10,000 to $15,000). It is similar in concept, if you will, to the past production costs of flat-screen TVs. If you recall, a few years ago it would cost you thousands of dollars for a 32 inch LCD TV, and you could only find them in specialty electronic stores. However, the production costs got better and now you can get a flat screen TV for ~$300 at a variety of locations like Walmart. So it doesn’t mean that there was no such thing as a flat screen TV before you were able to buy one, or that no one was using them. It was only accessible to a certain segment of the population. Using that as an example, as the cost of the MaterniT2 test has decreased, so the number of women who are able to access the MaterniT21 test has increased.
What does it cost?
More and more insurance companies are covering the cost of the test, which costs approximately $1,000 to $2,000, and those covered by HMO plans may need to get prior approval. However, Sequenom works with your insurance company for payment. However, if the insurance company rejects the claim, or you are not insured, most patients are only liable for a maximum of $235.
What is the process?
Your blood is either taken at your health care provider’s office or you are sent to a separate lab, which may be a distance away depending on your home state. The blood is currently sent to California for analysis, and it takes approximately eight business days for the pregnant woman to receive the test results.
How does it work?
The lab scans your blood looking for the DNA chromosomes. Scientists (or genetists) know that 3-6% of the blood in your body is from the fetus or carries the fetus’ genetic makeup. They scan your blood to see how often, for example, the T21 chromosome comes up. If they see it more than they should, that is the red flag that someone is making more of it, because if you are carrying a fetus with 3 strands of the T21 DNA (what causes Down Syndrome) and not 2 strands, it would be seen more often in your blood scan. Since you don’t have Down Syndrome, they assume it is the fetus producing the extra chromosome and would give you a positive result. If it looks the way they expect, it is negative. It is important to note that the results provided will be either positive or negative for T21 and positive for T18 or T13. (If you hear nothing about T13 or T18, it is therefore presumed negative.)
How accurate is it?
The key is that, while 99% accurate, it is not definitive as the amnio or a CVS. It is still considered a screen because it is screening your DNA. However, it is superior in accuracy than traditional trimester blood test screenings, quad tests, integrated screening, or sequential screenings since it is actually scanning for DNA and not hormones. Yet a CVS or amniocentesis actually analyzes the DNA strand itself.
So with the MaterniT21 test, you still have a risk factor; albiet a lower one prior to receiving the test. For some, this is still an acceptable level of assurance. For others, it is a more acceptable risk than the miscarriage risks associated with CVS or amniocentesis, which also have higher false positive rates than the MaterniT21 test. So, it is important to speak with a genetic counselor to determine how your own findings, after a first trimester screening, a quad test, integrated or sequential screening, relates to the screening and diagnostic options available to you and your particular needs, wants and desires.
More and more information will be disseminated to the public over the next year as this test is marketed, published, reported, and otherwise provided as an option for pre-natal care screenings. As always, talk to your medical provider to see what is right for you.
Disclaimer: I am not a doctor so any information provided within this post should not be construed as medical advice or counseling, and was based on data interpreted by me. For full information, you should visit the sites linked within this post or conduct your own research and analysis, including those living with Down Syndrome. I received no compensation for this post.
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