Down Syndrome better detected in DNA blood test than "standard methods?"

 Dr. Mary Norton (UCSF) conducted a study of about 16,000 pregnant women and found that a cell-free DNA blood test performed at about 10-14 weeks gestation was able to diagnose Down syndrome more accurately than the standard screening methods. This test was also more effective in diagnosing Edwards syndrome and Patau syndrome, than the standard methods.
 In the United States alone, down syndrome is the most common genetic condition and it affects nearly 1 in every 700 babies born. Down syndrome occurs when an extra chromosome 21 is created and is copied in the cells through the body. As we know there are characteristics from this extra chromosome like flattened fatal features, reduced muscle tone, upward slanting eyes and small hands and feet.
  All pregnant women are offered testing and screenings for Down syndrome. During the first trimester, a test of both protein levels and hormones in the woman's blood are combined and to check for chromosomal abnormality linkage along with an ultrasound that measures the baby's neck tissue for increased fluid build up that could result in abnormalities. The results of the test and the ultrasound are compared with the mother's age to determine the risk of the baby having down syndrome.
  Pregnant women who are at a high risk of having a baby with down syndrome are recommnded to have the cell-free fetal DNA (cfDNA) test. This consists of a small amount of fetal DNA taken from the pregnant woman's blood, to detect any copies of chromosome 21. Dr. Norton and her team have said the cfDNA test has proved itself to be highly accurate in HIGH-risk women, however for the lower-risk women, the results are not as clear.
  For the cfDNA test, Dr. Norton and her team had 18,955 pregnant women from around age 30 from 35 different medical centers in over six countries. About 24% of these women were over 35, which increases the risk of down syndrome, giving the other 76% a lower risk. during the 10-14 week gestation, each woman was given the first trimester combined test AND the cfDNA test. Out of the 18,955, the team was able to get the test results and monitor pregnancy outcomes for 15,841 of the women.
   The team found that the cfDNA test was able to identify 38 cases of down syndrome while the first trimester test only detected 30 out of 38 cases. It was also learned that the cfDNA resulted in nine false-positive results while the first trimester combined test showed 854. There was also the detection in Edwards syndrome and Patau syndrome in the cfDNA test which was not as accurately found in the first trimester combined test.
  The result of the cfDNA test in women with a lower risk will lead to fewer false-positive results than the standard screening which in the overall result, there can be fewer invasive tests and related miscarriages, but health care providers and pregnant women themselves do need to be aware of the downfalls of the cfDNA testing much like any new study. The normal screening will capture a wider range of abnormalities.
I found this article to be really interesting. I think it is great that they are able to use blood tests rather than more invasive testing methods because it can be more comfortable and save more lives. The only downside to this like the article mentioned was that this blood test is not able to pick up a lot of other diseases or genetic mutations that the standard methods are able to identify. Maybe in the future that will be an advancement to look for!

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