Tuesday, November 1, 2011

New test for EARLY detection of Down Syndrome

Many expecting parents worry about the chance that their unborn baby has Down Syndrome. This genetic disease 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. Alternatively, the nuchal translucency test (the NT test) is a safe test done at 12 weeks of pregnancy can help determine if the chance for Down Syndrome is high or low with about 90% accuracy.
However, there is now an amazing blood test that can be done on the mother’s blood and can determine with 99% accuracy if the baby she is carrying does or does not have Down Syndrome. The test is called the MaterniT21 test, available only from Sequenom Labs.
The MaterniT21 test was validated in high-risk couples that had either advanced maternal age, an abnormal fetal ultrasound or abnormal screening test, or a family history of Down Syndrome. We still do not know if the accuracy will be as high for low-risk couples, but there is every reason to believe that it will.
Down Syndrome, also called Trisomy 21, means that the person has 3 copies of chromosome 21 instead of the normal 2 copies that the rest of us have. The MaterniT21 test uses breakthrough technology to identify microscopic particles of DNA from the baby that are present in the mother’s bloodstream.  The amount of DNA from the fetal chromosome 21 is compared to DNA from other fetal chromosomes in the blood sample. If the amount of chromosome 21 DNA is normal, then the baby does not have Trisomy 21. Thus 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.

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