A new study suggests that DNA testing during the early stage of pregnancy can more accurately detect fetal abnormalities, thus lessening chances of going through invasive screening procedures.
Researchers led by Diana Bianchi, M.D. of Tufts Medical Center in Boston found that DNA testing in pregnant women on the ninth to 10th week of pregnancy can screen for disorders brought by missing or excess chromosomes such as Edward syndrome and Down syndrome.
According to the National Down Syndrome Society (NDSS), one in every 691 babies born in the United States has Down Syndrome which is the most commonly occurring chromosomal defect.
Edwards Syndrome, on the other hand, occurs in one in every 5,000 babies thus considering it a rare disease.
Bianchi's team recruited about 2,000 pregnant women who underwent standard prenatal screening and fetal DNA testing. Both procedures identified eight chromosomal abnormalities, including five of Down syndrome.
However, the false alarm rate for Down syndrome identified through DNA testing, which is 0.3 percent, was way lower than the rate identified through standard prenatal screening, which is 3.6 percent.
Additionally, the DNA testing gave fewer false alarms for Patau syndromes (trisomy 13) and Edwards syndrome (trisomy 18). This means far fewer pregnant women would be subjected to a series of diagnostic testing, including invasive ones such as amniocentesis.
"It offers women a safe and accurate alternative" for prenatal screening, said study leader Bianchi to the Associated Press.
Standard prenatal screening includes ultrasounds and different blood tests. It detects a problem but doesn't directly test for one. Once the problem is detected, the mother will be asked to undergo diagnostic testing that pose a small risk of miscarriage.
DNA testing, on the other hand, will just use a sample of the mother's blood. DNA from the mother's blood sample will be sequenced and mapped to various chromosomes. The result will then be compared to what's normal at that stage of pregnancy.
According to College of Obstetricians' genetic committee head Nancy Rose, M.D., though it looks promising, it only involved a very small number of participants. A larger research would be needed to substantiate changes in the screening recommendations for pregnant women, NPR reported.
Further details on this study can be read in the Feb. 27 issue of the New England Journal of Medicine.
