Performance of Cell-Free DNA Sequencing-Based Non-invasive Prenatal Testing: Our Experience on 36456 both Singleton and Multiple Pregnancies.

Abstract

Background: To describe the clinical practice and performance of cell-free DNA sequencing-based noninvasive prenatal testing as a screening method for detecting trisomy 21, 18, and 13 (T21, T18, and T13, respectively), as well as sex chromosome aneuploidy (SCA), in a general Italian pregnancy population.Methods: The AMES-accredited laboratory offers noninvasive prenatal testing in maternal blood as a clinical screening test for foetal T21, T18, T13 and SCA. Samples were sequenced on a NextSeq 550 (Illumina) using the VeriSeq NIPT Solution v1 assay.Results: A retrospective analysis was performed on a cohort of 36456 consecutive maternal blood samples, including 35650 singleton pregnancies, 800 twin pregnancies, and 6 triplet pregnancies, which were tested between April 2017 and September 2019. The cohort included 46% elevated-risk and 54% low-risk patients. Genetic and/or clinical outcomes were available in 36000 cases (98.7%). In the overall cohort, 356 (1%) results were indicative of classic trisomy: 254 T21, 69 T18, and 33 T13. In addition, 145 results (0.4%) were indicative of SCA. Of the combined 501 screen-positive cases, 484 had confirmatory diagnostic testing results available: 99.2% (247/249) of T21 cases, 91.2% (62/68) of T18 cases, 84.4% (27/32) of T13 cases, and 86.7% (117/135) of SCA cases were confirmed. Follow-up data were available for 98.8% of the 35955 cases reported as unaffected by trisomy or SCA. No false negative cases were reported. The sensitivity of NIPT was 100.00% for T21 (95% Cl 98.47-100.0), T18 (95% Cl 94.17-100.0), T13 (95% Cl 87.54-100.0) and SCA (95% Cl 96.62-100.0). The specificities were 99.99% (95% Cl 99.98-100.0), 99.98% (95% Cl 99.96-100.0), 99.99% (95% Cl 99.97-100.0), and 99.95% (95% Cl 99.92-99.97) for T21, T18, T13, and SCA, respectively.Conclusion: This retrospective analysis of a large cohort of consecutive patients who had whole-genome sequencing-based NIPT for classic trisomies and SCA showed excellent detection rates and low false positive rates.

The association between fetal Doppler and uterine artery blood volume flow in term pregnancies: a pilot study

“…Only term pregnancies (37 0/7 -41 6/7 weeks of gestation) were included. To be considered eligible, all the patients should have performed the first and second-trimester screening for Down's syndrome and fetal structural anomalies detection [16]. Exclusion criteria included the following: intrauterine death, chromosomal anomaly, fetal malformation, multiple pregnancies, and maternal age less than 18 years.…”

Ethical issues associated with prenatal screening using non‐invasive prenatal testing for sex chromosome aneuploidy

“…A large retrospective analysis of SCAs reported PPVs for 45,X; 47,XXY; 47,XXX and 47,XYY as 18.14%, 58.73%, 80.29% and 71.19%, respectively 34 . In contrast, another study using a paired‐end sequencing method, which can help minimise the impact of maternal SCA mosaicism on false positive results, reported higher PPVs of 85.2%, 87.5%, 83.3% and 100% for 45,X; 47,XXY; 47,XXX and 47,XYY, respectively 35 …”

“…34 In contrast, another study using a paired-end sequencing method, which can help minimise the impact of maternal SCA mosaicism on false positive results, reported higher PPVs of 85.2%, 87.5%, 83.3% and 100% for 45,X; 47,XXY; 47, XXX and 47,XYY, respectively. 35…”