Researchers have developed a safer prenatal Down’s syndrome test:
Quake’s team demonstrated the accuracy of the new genetic test in a small study involving 18 women.It accurately identified the nine women with a Down’s syndrome pregnancy and three others with fetuses with different chromosomal disorders, the researchers wrote in the journal Proceedings of the National Academy of Sciences.
“It’s the first universal, noninvasive test for Down syndrome. So this should be the first step in putting an end to invasive testing procedures like amniocentesis and chorionic villus sampling,” Quake said in a telephone interview.
Blood tests for pregnant women like the alpha-fetoprotein test can find potential signs of a chromosomal disorder such as Down’s, but cannot diagnose it with certainty.
Quake said such tests serve as only “indirect and weak predictors of what’s going on.”
For a definitive determination, women must have an invasive diagnostic procedure such as amniocentesis or chorionic villus sampling. This is done typically after the 15th week of pregnancy.
These procedures carry a small risk — roughly 1 percent — of causing a miscarriage or birth defects.
Because of that, their routine use has been mostly by women age 35 and older at higher risk for having Down’s syndrome babies. Scientists have been working for years to devise safer, noninvasive tests suitable for any pregnant woman.
Quake said the new test also could be administered much earlier in a pregnancy than amniocentesis or CVS — potentially as early as five weeks after conception. And the results are back within a couple of days, instead of two to three weeks.