Non-invasive blood test could reshape standards in prenatal testing

New research has found that routine screening using a non-invasive test that analyzes fetal DNA in a pregnant woman's blood can accurately detect Down's syndrome and other genetic fetal abnormalities in the first trimester. Published early online in Ultrasound in Obstetrics & Gynecology, the results suggest that the test is superior to currently available screening strategies and could reshape standards in prenatal testing.

Current screening for Down's syndrome, or trisomy 21, and other trisomy conditions includes a combined test done between the 11th and 13th weeks of pregnancy, which involves an ultrasound screen and a hormonal analysis of the pregnant woman's blood. Only chorionic villus sampling and amniocentesis can definitely detect or rule out fetal genetic abnormalities, but these are invasive to the pregnancy and carry a risk of miscarriage.

Several studies have shown that non-invasive prenatal diagnosis for trisomy syndromes using fetal cell free (cf) DNA from a pregnant woman's blood is highly sensitive and specific, making it a potentially reliable alternative that can be done earlier in pregnancy.

An Ultrasound in Obstetrics & Gynecology study by Kypros Nicolaides, MD, of the Harris Birthright Research Centre for Fetal Medicine at King's College London in England, and his colleagues is the first to prospectively demonstrate the feasibility of routine screening for trisomies 21, 18, and 13 by cfDNA testing. Testing done in 1005 pregnancies at 10 weeks had a lower false positive rate and higher sensitivity for fetal trisomy than the combined test done at 12 weeks. Both cfDNA and combined testing detected all trisomies, but the estimated false-positive rates were 0.1% and 3.4%, respectively.

News-Medical.net, June 10, 2013

 

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