Hemolysis and Fetal Fraction in Cell-Free DNA Blood Collection Tubes for Noninvasive Prenatal Testing.

Background: Lysis of maternal white blood cells in prenatal cell-free DNA (cfDNA) test samples increases the level of maternal DNA and consequently decreases fetal fraction.

Objective: The objective of this study was to determine whether hemolysis, traditionally used as a marker for cell lysis, is correlated with a decrease in fetal fraction in maternal blood samples collected in specialized cfDNA tubes for noninvasive prenatal testing.

Methods: In the first part of the study, blood from pregnant women was collected into three Roche Cell-Free DNA Collection Tubes.

Prenatal Screening for 22q11.2 Deletion Using a Targeted Microarray-Based Cell-Free DNA Test.

Objective: To determine the performance of a targeted microarray-based cell-free DNA (cfDNA) test (Harmony Prenatal Test®) for the identification of pregnancies at increased risk for 22q11.2 deletion.

Methods: Test performance was determined in 2 steps including a total of 1,953 plasma samples.

Selective analysis of cell-free DNA in maternal blood for evaluation of fetal trisomy.

Objective: To develop a novel prenatal assay based on selective analysis of cell-free DNA in maternal blood for evaluation of fetal Trisomy 21 (T21) and Trisomy 18 (T18).

Methods: Two hundred ninety-eight pregnancies, including 39 T21 and seven T18 confirmed fetal aneuploidies, were analyzed using a novel, highly multiplexed assay, termed digital analysis of selected regions (DANSR™). Cell-free DNA from maternal blood samples was analyzed using DANSR assays for loci on chromosomes 21 and 18.