New Test for Trisomy 21 Less Invasive

    The age at which women are choosing to start a family is getting older and older. With increased age comes a greater risk of Down Syndrome (Trisomy 21) at birth. According to the American Journal of Obstetrics & Gynecology, a blood plasma test during pregnancy may be just as efficient at predicting risk of Trisomy 21 as more invasive tests.

    Testing involves fetal DNA sequencing from maternal plasma. Researchers already have the test that can evaluate fetal DNA, but they continue to work out the kinks and reduce the cost of testing so it can be more readily available to expecting mothers. Today, chemical markers are more commonly used to determine risk of Trisomy 21. Based upon the new test, maternal plasma is used for fetal DNA sequencing and the extra chromosome may be found during the testing.



    Nearly 450 women at increased risk for Trisomy 21 were involved in the study. The test resulted in 39 positive tests for Trisomy 21 with only one false positive. This gave the researchers a specificity percentage of 99.7%.

    Doctors continue to use maternal plasma testing for a variety of chromosomal and fetal disorders in hopes of increasing the viability of the results and giving expecting mothers a better, more accurate result.

    Source: American Journal of Obstetrics & Gynecology. Mathias Ehrich, MD; Cosmin Deciu, MSc; Tricia Zwiefelhofer; John A. Tynan, DPhil; Lesley Cagasan, MSc; Roger Tim, DPhil; Vivian Lu; Ron McCullough, DPhil; Erin McCarthy; Anders O. H. Nygren, DPhil; Jarrod Dean; Lin Tang, DPhil; Don Hutchison, MSc; Tim Lu, DPhil; Huiquan Wang, DPhil; Vach Angkachatchai, DPhil; Paul Oeth, MSc; Charles R. Cantor, DPhil; Allan Bombard, MD; and Dirk van den Boom, DPhil. March 2011 Edition.