Corrected on 10/07/08: An earlier version of this article
incorrectly suggested that all pregnant women should get, rather
than be offered, Down syndrome screening. Pregnant women have
been waiting a long time for a blood test to definitively
diagnose Down syndrome, and one may finally be on the near
horizon. Researchers report in the Proceedings of the National
Academy of Sciences that they've overcome a significant hurdle
in providing such a test, which won't require them to sort
maternal genetic material from a fetus's. Another test
manufactured by Sequenom could be ready as early as June,
according to the New York Times. Neither method, though, has
been rigorously tested in enough women to ensure that it will
predict, with absolute certainty, which babies carry the Down
genetic defect and which ones don't. The disorder occurs in as
many as 1 in 800 babies and causes mental retardation, facial
abnormalities, heart defects, and other problems. At this point,
the two definitive ways to diagnose Down involve