Non-Invasive Prenatal Testing (NIPT)
EARLY detection of Down Syndrome and other fetal DNA abnormalities
Many expecting parents worry about the chance that their unborn baby has Down Syndrome (Trisomy 21) or some other genetic condition. Trisomy 21 is a genetic disease that nearly always develops after conception and therefore is NOT inherited from the parents. Amniocentesis has long been available as a diagnostic test but poses a risk of losing the pregnancy.
Starting in 2005, we have done the nuchal translucency test (the NT test) for the early detection of Down Syndrome. This is a safe test done at 12 weeks of pregnancy that can help determine if the chance for Down Syndrome is high or low with about 90% accuracy. But there is a new and better test now available!
New Technology can identify fetal DNA in the mother's blood
The newest technology is called Non-Invasive Prenatal Testing (NIPT). The NIPT blood test can be done on the mother’s blood and can determine with over 99% accuracy if the baby she is carrying does or does not have Down Syndrome and other conditions as well. The test is offered by many different labs. One version of the test that we like is called the MaterniT21 Plus test, available only from Sequenom Labs. Another is the Verifi test from Progenity.
[There are many labs now that offer NIPT but some do not run the test themselves, they send it to Illumina, the company that manufacturers the DNA sequencers used for this test. Progenity (see above) does this.]
Down Syndrome, also called Trisomy 21, means that the fetus has 3 copies of chromosome 21 instead of the normal 2 copies that the rest of us have. The NIPT test uses breakthrough technology to identify microscopic particles of cell-free DNA that are present in the mother’s bloodstream. The amount of DNA from the chromosome 21 is compared to DNA from other chromosomes in the blood sample. If the amount of chromosome 21 DNA is normal, then the baby does not have Trisomy 21.
Further advances in this type of testing continue to be made. For example, the NIPT full report includes testing for Trisomy 21 (Down Syndrome), Trisomy 18 (Edward Syndrome), Trisomy 13 (Patau Syndrome) fetal sex determination, detection of abnormal amounts of X or Y chromosome DNA, and other conditions as well, called micro-deletion syndromes.
The NIPT test checks for
abnormalities related to the number of X or Y chromosomes. Normal
females are XX and normal males are XY. However, there are certain rare
disorders, called sex-chromosome disorders, that occur spontaneously.
These include X0 (the baby has only 45 chromosomes, due to missing one X chromosome, which is called Turner Syndrome), and XXY, having an extra sex-chromosome, (called Klinefelter's Syndrome).
There is also XYY and XXX, even more rare. Some microdeletion syndromes can also be detected using this test. These are conditions where a portion of a chromosome is missing rather than an entire one.
In conclusion, a simple blood test, done as early as 10 weeks of pregnancy, can in the great majority of cases provide needed reassurance to concerned expectant parents by providing fetal DNA information - all done without posing any risk of pregnancy loss or having to go through an invasive medical procedure.
**COST ISSUES with NIPT TESTING**
An unexpected problem has developed due to these new NIPT DNA tests. They are very expensive tests and they are not always covered by health insurance providers even when we think they should be. Some labs will limit the patient’s out-of-pocket expense even if the test is denied by the insurance or if there is a high patient deductible.
We will help you work through this issue but you might wish to contact your insurer if you plan to have this test done to find out what your cost is. You also might have to contact the genetic testing laboratory to work out the final billing arrangements. We have been advised by the genetic testing labs that we work with that they will try to keep your out-of-pocket costs as low as they can.