Test for Down Syndrome Called 'Major Advance'

A DNA-based blood test appears to be more committed in detecting attainable Down syndrome in unborn children than new screening methods for the genetic illness, researchers publicize.

The test exhibited absolute authenticity in a clinical measures, detecting Down syndrome in all 38 women whose children had familial the sickness, the researchers description in the April 2 issue of the New England Journal of Medicine.

By comparison, gratifying screening methods and no-one else detected Down syndrome in 30 of the 38 expecting mothers, the psychotherapy authors said.

In the test, clinicians analyze fetal DNA circulating freely in a pregnant girl's bloodstream. Greater quantities of fetal DNA -- assumed pronounce cell-clear DNA -- in a girl's blood are an indication that her unborn child suffers from Down syndrome, the researchers said.

"It is handily a enlarged test than what we'back hint to currently using," said scrutiny guide author Dr. Mary Norton, a professor and vice chair of clinical and translational genetics at the University of California, San Francisco. "If one is looking at screening specifically for Down syndrome, there's no ask this test is augmented for that tilt."

Despite its accuracy, experts inform that mothers should follow happening any sure result taking into consideration an invasive methodical test such as amniocentesis past making any decisions re their pregnancy.

"Nobody wants a needle in their uterus considering they can obtain a blood test, but that's just not the quirk it works in 2015," said Dr. Joe Leigh Simpson, senior vice president of research and global programs at the March of Dimes. "This [supplementary exam] is a major bolster, but you'a propos yet going to have to uphold the results."

Simpson compared a certain repercussion in a cell-pardon DNA exam to a distinct cancer screen. "We'approaching speaking not going to be treated for cancer vis--vis the basis of an X-ray. We'just about going to have a biopsy to locate out what the matter actually is," he said.

Down syndrome occurs when a baby has an additional copy of chromosome 21 in its DNA. The birth oddity can cause mammal and studious disabilities, as swiftly as lifelong health problems.

Up to now, screening for Down syndrome has effective an earlier blood exam and an ultrasound, the U.S. Centers for Disease Control and Prevention says. The blood test looks for patterns of various substances in a mom's blood that are connected as soon as chromosomal problems that guide to Down syndrome, though the ultrasound examines the fetus for indications of birth defects.

The new clinical proceedings compared this screening method to the cell-clear DNA screening test, which takes place at 10 to 14 weeks of pregnancy and has been handy back 2011.

Earlier studies of cell-pardon DNA screening focused upon older women believed to be at difficult risk for birth defects, but this proceedings followed forward-thinking than 15,000 women when an average age of 31. One-quarter were gone 35, the age at which women traditionally have been considered high risk.

Besides its mighty accuracy, the cell-pardon DNA test plus had a much lower disloyal-sure rate than happening to usual screening -- 0.06 percent opposed to 5.4 percent taking into consideration all right screening, the psychiatry authors said.

"There's no ask that cell-arbitrator not guilty DNA for screening for Down syndrome is a augmented mousetrap," Simpson said.


The test does have drawbacks, however.

Because it is focused specifically upon Down syndrome, the cell-forgive DNA screening test can overlook indications of tallying types of birth defects detected by conventional screening methods, Norton said.

The test along with won't take motion properly for pregnant women without satisfactory fetal DNA loose in their bloodstream.

Obese women, in particular, are less likely to have sufficient forgive-loose fetal DNA, Norton said.

The test moreover can be fooled if a mom has an excessive amount of fetal DNA from some substitute source, once an undiagnosed cancer or a twin that has died in utero, Simpson said.

Sara Weir, president of the National Down Syndrome Society, noted an even broader event subsequent to both the cell-forgive DNA test and supplementary blood screening tests for birth defects -- they aren't regulated by the U.S. Food and Drug Administration, but by an arm of the Centers for Medicare and Medicaid Services.

"The FDA is the gold to your liking for variable drugs, diagnostics and supplementary devices, and we would considering to see these tests regulated by the FDA," Weir said. "We are scared that women are going to make decisions upon maintaining their pregnancy based upon disloyal positives. It needs to be greater than before regulated."

The clinical measures was funded, in share, by Ariosa Diagnostics, manufacturer of a cell-loose DNA prenatal screen.