The investigators state that a DNA-based blood exam shows to be more efficient in identifying probable Down syndrome in future children than other screening techniques for the hereditary condition.
The investigators’ statement in the April 2 issue of the New England Journal of Medicine says that in an experimental tryout, the exam showed exemplary precision in identifying Down syndrome in all 38 women whose offsprings had inherited the condition.
They stated that in contrast, traditional screening techniques only identified Down syndrome in 30 of the 38 pregnant women. In the examination, doctors scrutinize fetal DNA flowing liberally in an expecting woman’s bloodstream. Larger amounts of fetal DNA – also recognized as cell-free DNA — in a woman’s blood signify that her expected child endures from Down syndrome.
“It is clearly a better test than what we’re currently using. If one is looking at screening specifically for Down syndrome, there’s no question this test is better for that purpose,” states research head writer Dr. Mary Norton, a lecturer and vice chair of clinical and translational genetics at the University of California, San Francisco.
Specialists advise that mothers ought to follow up any affirmative outcome with an enveloping diagnostic exam like amniocentesis prior to creating conclusions concerning their pregnancy regardless of its correctness.
“Nobody wants a needle in their uterus when they can get a blood test, but that’s just not the way it works in 2015. This [new test] is a major advance, but you’re still going to confirm the results, ” says Dr. Joe Leigh Simpson, superior vice president of research and global projects at the March of Dimes. Simpson evaluated an affirmative outcome in a cell-free DNA test to an affirmative cancer screen. “We’re not going to be treated for cancer on the basis of an X-ray. We’re going to have a biopsy to find out what the situation actually is,” he stated.
When an infant has a spare copy of chromosome 21 in its DNA, Down syndrome arises. The birth deficiency can cause bodily and psychological disorders, with lifetime wellbeing complications.
The U.S. Centers for Disease Control and Prevention stated that until now, screening for Down syndrome has concerned an advance blood exam and an ultrasound. The exam searches for patterns of different matters in a mother’s blood that are linked with chromosomal complications that direct to Down syndrome, whereas the ultrasound inspects the fetus for symptoms of birth deficiencies. The recent medical tryout evaluated this screening technique to the cell-free DNA screening exam, which happens at 10 to 14 weeks of pregnancy.
Previous investigations of cell-free DNA screening centered on older women thought to be at superior threat for birth deficiencies, although this tryout went after over 15,000 women with a common age of 31. One-fourth were more than 35, the age upon which women usually have been assumed high threat. The research writers stated that the cell-free DNA exam also had greatly lower false-positive average than typical screening, besides its firm precision — 0.06 percent against 5.4 percent with typical screening.
“There’s no question that cell-free DNA for screening for Down syndrome is a better mousetrap,” says Simpson. Yet, the exam does have negative aspects. Since the cell-free DNA screening exam centers exclusively on Down syndrome, it can neglect symptoms of further kinds of birth deficiencies identified by typical screening techniques, says Norton.
The exam also won’t function accurately for pregnant women with no sufficient fetal DNA hovering in their bloodstream. Fat women, for example, are less expected to have sufficient free-hovering fetal DNA, says Norton.