Advanced/Secondary Blood Test for Detecting down Syndrome

Yes, I took the Maternity21 test. I took it as the ONLY test I took, as it is diagnostic, and I didn't see the point in doing the screen when the Maternity21 is so accurate. It also let me know the sex of the baby at 11 weeks. It isn't consider an advanced or secondary test, it is the new go to test.

Sorry I can't help you with taking it due to irregular results.

I took the MaterniT21 test this summer when my screening test gave me a high risk factor for DS. I too had it done because it was a non-invasive test compared to the amnio, and with three other children (who don't have it) I just wanted to be as prepared as possible if this one would have it. My OB and the High Risk/genetics Dr. both recommended this test. My results came back negative for DS. I can't tell you how accurate they were yet as I am still 6 weeks away from delivery.

The test was very simple... I went to the lab with the kit the Dr. gave me. They drew the blood and packaged to be sent. Then about 10 days later they called with the results.

Yes - it's very new and highly accurate for DS and the Trisomys.

My friend lost her baby after a CVS and was happy to have just a blood test this time!

I'm just starting to learn about fetal risk testing for my job, and had not heard of the test yet, so I did a little research. The test, MaterniT21 plus, is made by a laboratory in San Diego (Sequenom: see www.sequenom.com) that specializes in chromosomal testing. They've developed a shotgun method that looks at fetal DNA in the mother's blood that comes from cells shed by the fetus to the placenta. It's an interesting technique, and one that appears to be very promising. Here's what you should know about it to help you make an informed decision:

The test is a "laboratory developed test." It was developed by a single lab and as such, is exempt from FDA control. This means that the FDA has not done anything to substantiate the claims of the test or the studies used to evaluate it.

There have only been 3 published studies using this test, all of which are authored by the scientists who developed the tests (that is, the company). This is not necessarily bad, just a bit limited. I was able to read the abstracts of each of the 3 studies, but I'll have to order the papers to get more detail. From what I can see from the abstracts, however (which is limited), studies look like they were conducted appropriately and responsibly, and at least one study had a large enough sample size to yield reliable statistics. The other two are probably adequately powered; this is a statistical term which means that the number of people tested was smaller than desirable, but probalby enough to yield reliable statistics, none-the-less.

The results are, I must say, quite good. For detecting trisomy 21 (Down Syndrome), the test is ~99.1% sensitive and 99.9% specific. This means that the test detects trisomy 21 when it is actually present 99.1% of the time, and does NOT falsely detect trisomy 21 in a "normal" pregancy. These are remarkable numbers, and are about as close to ideal as you can get for a test, and appear to apply almost equally as well for pregancies involving multiples (twins, tripliets), as for singletons. I say almost, because another statistical indicator, the confidence interval, is quite wide for sensitivity in multiples (59 - 100%, vs. 96.3 - 99.8% for singletons), meaning that there could be a much larger margin for error in correctly identifying a trisomy, if present. Sensitivity and specificity are equally as good for detecting two other trisomies: 13 (Patau Syndrome) and 18 (Edwards Syndrome), which are much more severe and debilitating than Down Syndrome (but also rare).

Something to keep in mind, however, is that all of the trials thus far are still considered pilot studies and were ONLY performed in women considered to have high-risk pregnancies. The largest trial studied the test in 4664 high-risk pregnancies, and the study authors' conclusion was: "Extending the scope of previous reports, this study demonstrates that plasma DNA sequencing is a viable method for noninvasive detection of fetal trisomy 21 and warrants clinical validation in a larger multicenter study."

Note that even the authors feel more testing is necessary to substantiate the claims of the test. Also, note that this test is, by the company's own claims, only for use in high-risk pregancies; that is, only for women who are of advanced maternal age (over 35, I assume), have a personal/family history of chromosomal abnormalities, have had a fetal ultrasound abnormality suggestive of aneuploidy (incorrect number of chromosomes), or who have had another positive serum screening test (alpha-fetoprotein). It is NOT designed to be a first-line test -- it is, by the company's own claims, intended to be a secondary, follow-up test to confirm a risk that has already been identified.

Currently, it appears this test is only being offered in a limited number of cities, and are carried out by a single lab. The cost is ~$1900, although apparently it may be covered by some insurance companies, with a patient shared cost of ~$235. If you have had a first-line test and have been informed that you're at greater risk of giving birth to a child with a chromosomal abnormality, this test could be a better option that CVS as it is non-invasive (just a simple blood draw). Keep in mind, however, that you will only get information about these three types of trisomy. There are many other genetic disorders that can be tested for using CVS or amniocentesis, so if your obstetrician has concerns about disorders other than trisomy 13, 18, or 21, the MaterniT21 plus test wil not be useful.

I hope this will help you make your decision, and I wish you all the best for a healthy pregnancy and delivery.