Safer Down Syndrome Test Hits Market Monday

Oct 18, 2011 4:26pm

Starting Monday, moms to be can opt for a safer prenatal test for Down syndrome — a genetic condition marked by mental retardation and early death that affects one in 691 babies.

MaterniT21, developed by San Diego-based biotech company Sequenom, can detect fetal DNA in the mother’s blood as early as 10 weeks into the pregnancy. That DNA reveals whether the fetus has the extra copy of chromosome 21 that causes Down syndrome.

Current prenatal tests, which require a sample of either amniotic fluid or placenta, are more invasive and carry a small risk of fetal injury or miscarriage.

“We believe that the MaterniT21 [test] will provide physicians and their patients with critical new information to help them make better informed decisions about the patients’ healthcare and pregnancies,” Sequenom CEO Harry Hixson Jr. said in a statement.

In a Sequenom-sponsored study, MaterniT21  spotted 209 of 212 Down syndrome cases — a feat researchers say would  save lives.

“This method can substantially reduce the need for invasive diagnostic procedures and attendant procedure-related fetal losses,” the study authors wrote in a report published Monday in the journal Genetics in Medicine.

But some experts worry the safer test could lead to more screening and more terminated pregnancies.

“The number of American women who will have to grapple with this information prenatally will substantially increase,” Dr. Brian G. Skotko of the Down syndrome program at Children’s Hospital Boston told the New York Times.

While MaterniT21 correctly identified 98.6 percent of Down syndrome cases, it incorrectly identified three of 1,471 normal fetuses as having the disorder, earning it a false positive rate of 0.2 percent. The existing tests — amniocentesis and chorionic villus sampling — have a false positive rate of up to 5 percent.

The risk of Down syndrome increases with maternal age, rising from one in 1,250 for a 25-year-old to roughly one in 100 for a 40-year-old. Sequenom said it developed the test for the estimated 750,000 high-risk pregnancies in the U.S. each year.

Like similar tests used to determine unborn babies’ sex or paternity, MaterniT21 has not been approved by the U.S. Food and Drug Administration.

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