Prenatal blood test detects Down syndrome

LOS ANGELES – A prenatal blood test that can detect Down syndrome in a fetus in early pregnancy is now available to doctors in 20 U.S. cities, says the developer of the test, Sequenom Inc.

The test is a milestone in prenatal testing because it’s the first noninvasive way to detect trisomy 21, the most common cause of Down syndrome.

Until now, women have had to undergo amniocentesis or chorionic villus sampling, both invasive tests, to detect Down syndrome.

A more recent strategy was to combine ultrasound testing with blood tests, but that test required confirmation with amniocentesis or CVS.

The blood test measures fetal DNA in the mother’s bloodstream. It is safe and effective, according to a study published online last week in the journal Genetics in Medicine. That study on pregnancies at high risk for Down syndrome found a detection rate of 98.6 percent (209 of 212 pregnancies). The false-positive rate was 0.2 percent (three of 1,471), and testing failed in 13 pregnancies.

Sequenom, the San Diego-based maker of the test, called MaterniT21, said it will initially be available to doctors who request it in 20 metropolitan areas in the U.S.

The out-of-pocket cost to patients with insurance will be no more than $235, the company said.

It will take eight to 10 days for doctors to receive the results of the test.