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DNA Test Effective in Detecting Fetal Disorders

Update Date: Feb 27, 2014 11:04 AM EST

Due to advancements made in science and technology, expectant mothers can undergo tests to screen for any genetic disorders in their unborn child. In a new study, researchers set out to examine the effectiveness of different screening tests. They reported that one particular DNA test provided highly reliable results.

For this study, headed by executive director of the Mother Infant Research Institute at Tufts Medical Center in Boston, MA, Dr. Diana Bianchi, the research team compared the effectiveness of different genetic testing methods. The team found that the Illumina Inc's genetic test was more reliable in finding cases of trisomy disorders in comparison to ultrasound tests and blood draws. Illumina's test, Verifi, also had a lower rate of producing false positives. The study was funded by Illumina, a DNA-sequencing company based in San Diego, CA.

Verifi works by counting the number of DNA fragments that are tied closely with trisomy disorders, such as Down syndrome. When the test picks up a higher than usual number of DNA fragments, the unborn fetus could have some kind of disorder. The expectant mother could then undergo a conclusive diagnostic test for more information. Two popular diagnostic tests are amnicoentesis and chorionic villus sampling.

"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, reported by the Los Angeles Times. Greene was not involved in the study. "With this new test, the number of women who get inappropriately or improperly labeled as having an abnormal fetus is very small. So that's a major advantage."

These genetic tests have been approved by the American Congress of Obstetricians and Gynecologists as well as other professional societies for expecting mothers over the age of 35. Women with a history of fetal disorders have also been approved to get these tests. These groups, however, stated that there was not enough evidence to determine if genetic tests would be beneficial for low-risk women, which prompted Dr. Bianchi to conduct another study.

The research team recruited 1,914 low-risk women from U.S. cities who were pregnant with one child. The researchers administered a DNA test and the standard tests for all women. The team calculated that the false positive rate for the DNA test for Down syndrome was 0.3 percent. The false positive rate for the standard tests was 3.6 percent. Out of the 1,365 female patients who were tested during their first or second trimester, 51 of them had false positives from the standard tests whereas only four had false positives from the Illumina test. The researchers reported similar results for the remaining 544 women who were tested in their third trimester. Despite attempting to perfect these screening tests, some critics do not believe that these tests are helpful all the time.

"People with Down syndrome are artists. They're poets. They're athletes. Their lives are happy ones and fulfilling ones. I have a sister with Down syndrome who certainly is a life coach for not only myself but for my entire family," said Brian Skotko, co-director of the Down Syndrome Program at Massachusetts General Hospital in Boston, according to NPR. "If the new tests become a routine offering, then we have to start to ask: Will babies with Down syndrome slowly start to disappear?"

The study was published in the New England Journal of Medicine.

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