ObjectiveTo evaluate the clinical performance of non‐invasive prenatal testing for trisomy 21, 18, and 13 using targeted cell‐free DNA (cfDNA) analysis.MethodsTargeted cfDNA analysis using DANSR™ and FORTE™ with microarray quantitation was used to evaluate the risk of trisomy 21, 18, and 13 in blinded samples from 799 singleton, twin, natural, and IVF pregnancies. Subjects either had fetal chromosome evaluation by karyotype, FISH, QF‐PCR, or karyotype for newborns with suspected aneuploidy at birth. The results of targeted cfDNA analysis were compared to clinical genetic testing outcomes to assess clinical performance.ResultsTargeted cfDNA analysis with microarray quantification identified 107/108 trisomy 21 cases (99.1%), 29/30 trisomy 18 cases (96.7%), and 12/12 trisomy 13 cases (100%). The specificity was 100% for all three trisomies. Combining this data with all published clinical performance studies using DANSR/FORTE methodology for greater than 23 000 pregnancies, the sensitivity of targeted cfDNA analysis was calculated to be greater than 99% for trisomy 21, 97% for trisomy 18, and 94% for trisomy 13. Specificity for each trisomy was greater than 99.9%.ConclusionTargeted cfDNA analysis demonstrates consistently high sensitivity and extremely low false positive rates for common autosomal trisomies in pregnancy across quantitation platforms. © 2015 Ariosa Diagnostics Inc. Prenatal Diagnosis published by John Wiley & Sons, Ltd.

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. Analytical validation was performed in 1,736 plasma samples. Clinical verification of performance was performed in an additional 217 prospectively ascertained samples from pregnancies with fetal deletion status determined by diagnostic testing. Results: Analytical sensitivity was 75.4% (95% CI: 67.1–82.2%) based on 122 samples with deletions ranging from 1.96 to 3.25 Mb. In 1,614 presumed unaffected samples, specificity was determined to be at least 99.5% (95% CI: 99.0–99.7%). In the clinical cohort, 5 of 7 samples from pregnancies affected with 22q11.2 deletion were determined to have a high probability of deletion. There were no false positive results in the 210 unaffected samples in this cohort. These clinical data are consistent with the performance demonstrated in the analytical validation. Conclusions: cfDNA testing using a targeted microarray-based technology is able to identify pregnancies at increased risk for 22q11.2 deletions of 3.0 Mb and smaller while maintaining a low false positive rate.

Purpose: To examine trends in patients submitting samples for cell-free DNA screening to determine whether they reflect a shift towards NIPT use in the low-risk population. Methods: A review of demographic information was performed for all specimens submitted to the Ariosa Diagnostics clinical laboratory for the Harmony V R prenatal test between January 1, 2014 and December 30, 2017. The proportions of specimens for patients under 35 years and 35 years and older were compared. Results: There was a significant increase in the proportion of specimens submitted by patients under 35, from 47.3% in 2014 to 60.3% in 2017 (Chi-square test, p < .001).Conclusions: The proportion of samples submitted to our laboratory by patients under 35 years has significantly increased in the 4-year subset, which represents the demographics of a diverse group of patients from across the globe. This suggests an increase in uptake of NIPT in the lowrisk population. ARTICLE HISTORY Objectives and protocolNon-invasive prenatal testing (NIPT) was initially recommended for women at increased risk of fetal aneuploidy by most professional society guidelines. With the publication of additional clinical studies, offering NIPT to all pregnant women was supported by subsequent guidelines. In addition, provider and public awareness of NIPT has increased over time. This study provides data on the proportion of patients under 35 years of age electing NIPT in a well-established commercial laboratory. We demonstrate an international trend over a 4-year time period with an increasing proportion of samples submitted by patients under 35 years.

ObjectivesVarious methods of fetal‐fraction measurement have been employed in conjunction with different approaches to cell‐free DNA testing for fetal aneuploidy. In this study, we determined the accuracy and reproducibility of fetal‐fraction measurement using polymorphic assays that are incorporated into the test design as part of the Harmony® prenatal test and evaluated whether the single nucleotide polymorphisms selected for and used in these assays can be applied broadly to all patient populations.MethodsClinical maternal plasma samples were assayed using a custom microarray with Digital ANalysis of Selected Regions (DANSR) assays designed to cover non‐polymorphic targets on chromosomes of interest for aneuploidy assessment (13, 18, 21, X and Y) and polymorphic targets for fetal‐fraction assessment. In a consecutive series of 47 512 maternal plasma samples, fetal‐fraction measurements based on polymorphic assays were compared with those from Y‐sequence quantitation. Reproducibility was examined between first‐ and second‐tube measurements for the same patient sample in 734 cases. The fraction of informative loci was calculated for 13 988 samples.ResultsThere was a strong correlation between fetal fractions determined using the polymorphic assays and using Y‐chromosome sequence quantitation (r = 0.97). Fetal‐fraction measurement between the first and second tubes was highly reproducible (r = 0.98). The fraction of informative loci observed in a clinical series was consistent with predictions based on assay design.ConclusionsThe method based on relative quantitation at polymorphic loci on a microarray is accurate and reproducible for fetal‐fraction estimation and is equally informative across global populations. This study provides a useful benchmark for ensuring the reliability and accuracy of fetal‐fraction measurement. © 2018 Roche Sequencing Solutions. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Factors associated with obtaining results on repeat cell-free DNA testing in samples redrawn due to insufficient fetal fraction,