DNA test Helps Identify Genetic Disorders in Unborn Children: Study

Prenatal DNA screening is effective in detecting Down syndrome in unborn children, according to a study.

 Researchers compared the effectiveness of various standard tests like ultra sound exams, simple blood tests and prenatal gene-screening in detecting genetic disorders and Downs syndromes. Researchers found that genetic test from a DNA sequencing firm Illumina Inc are more reliable in detecting trisomy disorders like Down syndrome, Edward syndrome and Patau syndrome.  

The Illumina test called verifi measures the DNA fragments in the unborn child by drawing a small amount of amniotic fluid or the liquid inside the womb that protects the fetus. The test confirms trisomy disorders only if more than two copies of chromosomes are found in the DNA of the fetus.

Dr. Michael Greene, chief of obstetrics at Massachusetts General Hospital, who wasn't involved in the study said , " 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. 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," reports Los Angeles Times.

The researchers collected blood samples for DNA testing and used standard screening tests of 1,914 women who were pregnant with one child to measure the false positive rates of detection. The mean age of the participants was approximately 30 years.

The results showed the false positive test for various DNA tests for Down's Syndrome was 0.3 percent and 3.6 percent for standard tests. The number of women from a total of 1,356 women who were tested during the first or second trimester showing false-positive for standard and Illunima tests were 51 and four respectively. The results were similar for the remaining 544 women who underwent tests during the third trimester.

According to the data by the Centers for Disease Control and Prevention (CDC), every year almost 6,000 babies are born with Down's syndrome in the U.S. meaning nearly one out of every 700 babies suffer from the condition. The new Verfi tests are approved by the American Congress of Obstetricians and Gynecologists who call it " a new generation test"  for all women including those ages 35 and above, with  high risks for giving birth to children with Down's syndrome or a family history of the condition.  

The research titled DNA Sequencing versus Standard Prenatal Aneuploidy Screening is published in the New England Journal of Medicine.