A study published in The Journal of Maternal-Fetal and Neonatal Medicine demonstrates that the fraction of fetal cell-free DNA (cfDNA) in maternal blood is unaffected by the mother's presumed risk for trisomy, offering support for the use of non-invasive prenatal testing (NIPT) for detecting genetic conditions such as Down syndrome in a broad patient population. Lead and senior authors of the study were Dr. Herb Brar, Director of Riverside Perinatal Diagnostics Center, and Dr. Mary Norton, Professor of Obstetrics and Gynecology, Lucile Packard Children's Hospital at Stanford University, respectively.
Results of the study, a post-hoc comparative analysis of the previously published "Non-invasive Chromosomal Evaluation" (NICE) study, showed that there were no significant differences in the fraction of fetal cfDNA in maternal blood in women who were stratified into three different trisomy risk groups based on maternal age, prenatal screening results or nuchal translucency measurement. The amount of fetal cfDNA in maternal blood is the principal factor in successfully detecting trisomies with NIPT. Trisomy refers to the presence of three chromosomes rather than two. Certain trisomies are known to cause genetic conditions. The study is available at: http://informahealthcare.com/doi/abs/10.3109%2F14767058.2012.722731
"The results of this study were particularly significant because they showed that fetal fraction of cfDNA does not vary significantly among pregnant women regardless of their predetermined trisomy risk," said Dr. Herb Brar. "This adds to the growing amount of research that suggests NIPT can offer an effective prenatal screening option in the general pregnant population."
NIPT is a new screening option that analyzes cell-free fetal DNA circulating in maternal blood to evaluate the risk of having a baby with Down syndrome and other common genetic conditions. It involves a single blood draw as early as 10 weeks' gestation and delivers a greater than 99 percent detection rate for trisomy 21, which causes Down syndrome. NIPT, using the Harmony™ Prenatal Test, also has shown to have fewer false positive test results; up to 50 times less than traditional prenatal screening options such as maternal serum screening.