![]() When a conceived cell implants into the mother, the cell has divided into further cells that perform certain functions. Some of us may remember cellular biology: the nucleus, mitochondira, etc. Now, here’s where we time travel back to high school. In the professional medical committee opinions and materials from the testing laboratories, where reference is made, often it is to “cell free fetal DNA.” So, I suppose I should be forgiven for not understanding that the DNA was not, in fact, fetal DNA. Figure 1 displays these laboratories’ respective NIPT tests in clockwise order, respectively. Currently, in the United States, there are four laboratories that provide NIPT: Sequenom, Ariosa, Verinata, and Natera. NIPT has received a lot of media attention, due in no small part to the private laboratories promoting their various versions of it. In talking about the newest form of prenatal testing, non-invasive prenatal testing (“NIPT”), he off-handedly mentioned, “well everyone knows cffDNA is really placental DNA.” Well, this everyone did not. One of the first conference attendees to walk up to talk about my poster was a medical geneticist that, we figured out, was stationed with me when I was in the United States Air Force. (I’ll have more on my particular poster later). Poster presentations are where you stand in front of a poster and present on the information it displays. There is where I learned I was mistaken about the basis for newest form of prenatal testing. This past week I gave a poster presentation at the Annual Clinical Meeting for the American College of Medical Genetics (ACMG). The Harmony non-invasive prenatal test is available as early as 10 weeks of pregnancy.For years, I’ve been presenting at conferences on prenatal testing for Down syndrome, explaining how the new tests are based on cell free fetal DNA or “cffDNA.” Turns out I was wrong. Amniocentesis results are accurate 99.9% of the time. Amniocentesis is associated with a small risk of miscarriage (approximately 0.5%). An amniocentesis is usually performed around or after the 16th week of pregnancy. ![]() The fluid is then sent to the laboratory to test the chromosomes. ![]() Amniocentesis (Amnio Test): Procedure that withdraws a small amount of the amniotic fluid that surrounds the fetus.CVS results are accurate approximately 98% of the time. CVS is associated with a small risk of miscarriage (approximately 1%). CVS is typically performed between 10 and 12 weeks of pregnancy. The tissue is then sent to a laboratory to test the chromosomes. Chorionic villi sampling (CVS): Procedure that takes a small amount of tissue from the developing placenta.Your healthcare provider may offer you one of the following follow-up diagnostic procedures to confirm: This means fewer than 1 in 1,000 Harmony tests yields a false-positive result. Harmony has a less than 0.1% false-positive rate for trisomies 21, 18 and 13. If the Harmony prenatal test shows you are high risk, it does not necessarily mean that the pregnancy has one of these genetic conditions. With traditional screening, as many as 1 in 20 women will receive a false-positive result. Traditional screening tests (maternal serum screening, first trimester screening, Quad screening) can miss as many as 20% of Trisomy 21 cases in pregnant women.
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