A test analyzing fetal DNA found in a pregnant woman’s blood proved much more accurate in screening for Down syndrome and another chromosomal disorder than the now-standard blood test, a new study has found. The promising results may change how prenatal screening for genetic diseases is done, though the test is costly and generally not yet covered by insurance for women at low risk.
The study, published in The New England Journal of Medicine, found the fetal DNA test was 10 times better in predicting cases of Down syndrome than the standard blood test and ultrasound screening, and five times better in predicting the other disorder, Trisomy 18. It also greatly reduced the number of false-positive results.
It could prevent many women who would otherwise get the standard blood test from needing to confirm positive results with invasive tests, which can be stressful, much more costly and carry small risks of miscarriage.
“Nine out of 10 women who are currently being referred for further testing would not need invasive tests,” said the lead author of the study, Dr. Diana Bianchi, the executive director of the Mother Infant Research Institute at Tufts Medical Center’s Floating Hospital for Children.
She is a paid advisory board member for Illumina, one of the laboratories performing the test. Illumina, which is based in San Diego, financed the study.
Greene, an associate editor at The New England Journal of Medicine, said that the study “would sort of be purer from an academic perspective if somebody else pays for it,” but that companies are “the ones that are going to finance the research to get it to where it’s marketable.”
He added, “We can’t have our cake and eat it too.”
