Monday, October 7, 2013

Universal Noninvasive Prenatal Testing for Down's Syndrome?

Today's NY Times returns us to Noninvasive Prenatal Testing for Down's Syndrome. 

... The newest screening test, highly accurate and noninvasive, relies on fetal genetic fragments found in the mother’s blood. Available commercially from four companies, this test is so accurate in detecting Down syndrome that few, if any, affected fetuses are missed, and far fewer women need an invasive procedure to confirm or refute the presence of Down, according to studies in several countries.

The new test, done late in the first trimester of pregnancy, can also detect other genetic diseases, like extra copies of chromosomes 13 and 18, and a missing sex chromosome. It is not yet approved by the Food and Drug Administration, however, and the American College of Obstetrics and Gynecology currently recommends it only for women at high risk for having a baby with a chromosomal abnormality.
The author then cites Tufts' Dr. Diana Bianchi as claiming that a "low risk" woman can get this test done if she's willing to pay for it. Actually, that may not always be true. NY State still tightly regulates laboratories' offering these tests and has been restricting the use of this technology to those at highest risk - age, history, or finding on ultrasound.
There are some drawbacks to these tests. 
... In a recent article in The New England Journal of Medicine, however, Stephanie Morain, a doctoral candidate at Harvard who studies medical ethics, and her co-authors said the fetal DNA tests have some disadvantages. They miss some chromosomal abnormalities detected by standard screening techniques, and they are “not widely covered by insurance.” Prices for the tests range from about $800 to more than $2,000, although some companies offer “introductory pricing” specials at about $200.
The high variation in pricing suggests that as the technology is offered to those women at lower risk, the price should come down to the lower range. It's my belief that insurance coverage may actually serve to keep prices higher rather than lower, but that's for another day.
While the article goes on to say the  tests are only  valid only in singleton pregnancies, some labs are performing the test for women who are carrying twins.
Some caveats - the first being that these tests presently only test for specific chromosomes so that a normal result does not mean a normal baby. In fact, there is no normal baby test. Conversely, an abnormal test result should be confirmed by an invasive test before making any final decisions. Having personally witnessed a mistaken result, I cannot emphasize this enough at the present time.
Finally, I agree with Dr. Bianchi  that the recent research findings in mice give hope that the day that Down's Syndrome can be ameliorated by prenatal therapy may be sooner rather than later. 
Faster Please.

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