DNA test screening in fetuses backed

LOS ANGELES — It’s billed as a faster, safer and more accurate way of screening expectant mothers for fetal abnormalities like Down syndrome, and proponents say it has become standard for prenatal care.

But as companies market their DNA-testing services, some experts complain that the tests have not been proved effective in the kind of rigorous clinical trials required of new drugs.

But a study published last week by the New England Journal of Medicine has verified that one of the tests can identify likely cases of Down syndrome and other genetic disorders caused by extra chromosomes in low-risk women with greater reliability than traditional screening methods.

The genetic test, marketed by the DNA-sequencing firm Illumina, did a better job of identifying cases of trisomy disorders than did tests based on ultrasound exams and blood draws, said Dr. Diana Bianchi, study leader and executive director of the Mother Infant Research Institute at Tufts Medical Center.

The genetic test also had a lower rate of false positives. “The current testing scares the wits out of a very large number of women, relatively speaking, who when they go through further testing are found to have totally normal fetuses,” said Dr. Michael Greene, chief of obstetrics at Massachusetts General Hospital.