Prenatal Test Identifies Trisomy 21 and Trisomy 18

In a study carried out in 13 US clinics a classification algorithm was developed using the prenatal test that correctly classified all trisomy 21 and trisomy 18 test samples.

Verinata Health, Inc. (St Carlos, CA, USA), a privately-held company dedicated to maternal and fetal health, developed the prenatal test, which uses massively parallel DNA sequencing of cell free fetal DNA from maternal blood.

For the study, blood samples were collected from 1,014 pregnant women at 13 US clinic locations prior to an invasive prenatal procedure (chorionic villus sampling (CVS), or amniocentesis). Samples were selected for use as training or test samples. From the 119 samples selected for the study, cell-free DNA (cfDNA) was extracted from the maternal plasma and the cfDNA was sequenced using massively parallel sequencing. Sixty-five of the samples were used as a training set to define a classification algorithm that was able to identify correctly 100% of trisomy 21 and trisomy 18 samples in an independent test set.

The algorithm also detected trisomy 9 in one test sample as well as the presence of trisomy 21 in two sets of twin pregnancies having at least one affected fetus. All 47 test samples were correctly classified for the autosomes and sex chromosomes.

Lawrence W. Platt, MD, professor of obstetrics and gynecology at the David Geffen School of Medicine at the University of California Los Angeles (UCLA; USA) and director of the center for fetal medicine and Women's Ultrasound in Los Angeles, remarked, "As the standard of practice is now to offer prenatal diagnosis to all of our patients, independent of age, the need for noninvasive diagnostic testing for chromosomal abnormalities without risk of miscarriage continues to be one of the highest priorities in diagnostic testing."

Results of the study appeared online in the April 2011 issue of Clinical Chemistry.

Related Links:
Verinata Health
David Geffen School of Medicine at UCLA