Analysis of the impact of PAPP-A, free β-hCG and nuchal translucency thickness on the advanced first trimester screening

Prenatal Screening of Trisomy 21: Could Oxidative Stress Markers Play a Role?

Despite significant progress in trisomy 21 (T21) diagnostic tools, amniocentesis is still used for the confirmation of an abnormal fetal karyotype. Invasive tests carry the potential risk of miscarriage; thus, screening biomarkers are commonly used before undergoing invasive procedures. In our study, we investigated the possible application of oxidative stress markers in the prenatal screening of trisomy 21. The DNA/RNA oxidative stress damage products (OSDPs), advanced glycation end (AGE) products, ischemia-modified albumin (IMA), alfa-1-antitrypsin (A1AT), asprosin, and vitamin D concentrations were measured in both maternal plasma and amniotic fluid in trisomy 21 (T21) and euploid pregnancies. The obtained results indicated increased levels of DNA/RNA OSDPs and asprosin with simultaneous decreased levels of vitamin D and A1AT in the study group. The diagnostic utility of the plasma measurement based on the area under the received operative characteristic (ROC) curve (AUC) calculation of asprosin (AUC = 0.965), IMA (AUC = 0.880), AGE (AUC = 0.846) and DNA/RNA OSDPs (AUC = 0.506) in T21 screening was demonstrated. The obtained results indicate a potential role for the application of oxidative stress markers in the prenatal screening of T21 with the highest screening utility of plasma asprosin.

The Significance of Apolipoprotein E Measurement in the Screening of Fetal Down Syndrome

Prenatal screening for Down syndrome (DS) is based on both noninvasive and invasive methods. Noninvasive, cell-free fetal DNA genetic tests are expensive, whereas biochemical methods remain imprecise. Amniocentesis is the most frequently used invasive diagnosis procedure, characterized by 99.8% diagnostic efficiency and less than 1% risk of miscarriage. The aim of this study was to evaluate the screening value of apolipoprotein E (ApoE) as a potential noninvasive biomarker for prenatal DS assessment. This study was conducted on a group of female patients who decided to undergo routine amniocentesis between the 15th and 18th week of pregnancy at the Department of Reproduction and Gynecological Endocrinology of the Medical University of Bialystok, Poland. For the purpose of this study, 20 women with DS fetuses were selected as the study group, and 20 healthy pregnant women with euploid fetus karyotypes as the control group. The plasma levels of ApoE were significantly higher in the study group compared to healthy subjects (p < 0.05). The area under the receiver operating characteristic (ROC) curve was 0.978 (p < 0.001), with the cut-off set to 1.37 mg/mL, which was characterized by 80% of sensitivity and 100% of specificity. The high sensitivity and specificity demonstrate the screening utility of maternal ApoE concentration in prenatal fetal DS screening.

Missed Down Syndrome Cases after First Trimester False-Negative Screening-Lessons to be Learned

Background and Objectives: Here, we performed a descriptive analysis of Down syndrome (DS) cases that were misdiagnosed and/or false-negative diagnosed after first trimester traditional screening via risk evaluation using ultrasound, biochemical markers, and different software programs. Our objective was to demonstrate the clear need to improve the application of prenatal DS screening programs using standardized ultrasound measurements, accurate pregnancy dating, analytical immunoassay performance, and properly selected medians. Materials and Methods: We performed a database search for the period 2010–2015 to analyze DS cases that were false-negative diagnosed after the first trimester of pregnancy, before the introduction of cell free fetal DNA-based tests by Romanian laboratories in 2015. First-trimester screening was performed using two software programs for prenatal DS risk calculation: Astraia and Prisca. The rationale for using both software programs was to assess the full risk using the maternal age combined test (based on nuchal translucency thickness, nasal bone, ductus venosus flow, tricuspid flow, free beta-human chorionic gonadotropin level, and serum pregnancy-associated plasma protein-A) and, in some cases, the triple test. Results: We identified seven DS cases that exhibited low risk for trisomy 21, and 6540 cases with a low risk for trisomy 21 and euploid fetus in the first trimester. Using Astraia software, 14 cases were diagnosed, and three cases were missed after risk calculation. Using Prisca software, four cases were missed. Additionally, one neonate had a missed prenatal diagnosis of atrio-ventricular canal defect. Conclusion: In Romania, the evaluation of DS risk depends on patient choice (without knowing the accuracy of the utilized tests) and on the operators’ skills. Both Astraia and Prisca software were developed by experts, who can prove their performance in DS screening. However, even in an ideal situation, false-negative results are possible. The application of first and second-trimester combined screening based on biochemical markers could be improved by the implementation of standardized protocols, professional guidelines for test application, and audit control.

The feasibility study of non-invasive fetal trisomy 18 and 21 detection with semiconductor sequencing platform

OBJECTIVE

Recent non-invasive prenatal testing (NIPT) technologies are based on next-generation sequencing (NGS). NGS allows rapid and effective clinical diagnoses to be determined with two common sequencing systems: Illumina and Ion Torrent platforms. The majority of NIPT technology is associated with Illumina platform. We investigated whether fetal trisomy 18 and 21 were sensitively and specifically detectable by semiconductor sequencer: Ion Proton.

METHODS

From March 2012 to October 2013, we enrolled 155 pregnant women with fetuses who were diagnosed as high risk of fetal defects at Xiamen Maternal & Child Health Care Hospital (Xiamen, Fujian, China). Adapter-ligated DNA libraries were analyzed by the Ion Proton™ System (Life Technologies, Grand Island, NY, USA) with an average 0.3× sequencing coverage per nucleotide. Average total raw reads per sample was 6.5 million and mean rate of uniquely mapped reads was 59.0%. The results of this study were derived from BWA mapping. Z-score was used for fetal trisomy 18 and 21 detection.

RESULTS

Interactive dot diagrams showed the minimal z-score values to discriminate negative versus positive cases of fetal trisomy 18 and 21. For fetal trisomy 18, the minimal z-score value of 2.459 showed 100% positive predictive and negative predictive values. The minimal z-score of 2.566 was used to classify negative versus positive cases of fetal trisomy 21.

CONCLUSION

These results provide the evidence that fetal trisomy 18 and 21 detection can be performed with semiconductor sequencer. Our data also suggest that a prospective study should be performed with a larger cohort of clinically diverse obstetrics patients.

Beyond Trisomy 21: Additional Chromosomal Anomalies Detected through Routine Aneuploidy Screening

Prenatal screening is often misconstrued by patients as screening for trisomy 21 alone; however, other chromosomal anomalies are often detected. This study aimed to systematically review the literature and use diagnostic meta-analysis to derive pooled detection and false positive rates for aneuploidies other than trisomy 21 with different prenatal screening tests. Non-invasive prenatal testing had the highest detection (DR) and lowest false positive (FPR) rates for trisomy 13 (DR: 90.3%; FPR: 0.2%), trisomy 18 (DR: 98.1%; FPR: 0.2%), and 45,X (DR: 92.2%; FPR: 0.1%); however, most estimates came from high-risk samples. The first trimester combined test also had high DRs for all conditions studied (trisomy 13 DR: 83.1%; FPR: 4.4%; trisomy 18 DR: 91.9%; FPR: 3.5%; 45,X DR: 70.1%; FPR: 5.4%; triploidy DR: 100%; FPR: 6.3%). Second trimester triple screening had the lowest DRs and highest FPRs for all conditions (trisomy 13 DR: 43.9%; FPR: 8.1%; trisomy 18 DR: 70.5%; FPR: 3.3%; 45,X DR: 77.2%; FPR: 9.3%). Prenatal screening tests differ in their ability to accurately detect chromosomal anomalies. Patients should be counseled about the ability of prenatal screening to detect anomalies other than trisomy 21 prior to undergoing screening.

European non-invasive trisomy evaluation (EU-NITE) study: a multicenter prospective cohort study for non-invasive fetal trisomy 21 testing

OBJECTIVE

To evaluate the performance of a directed non-invasive prenatal testing method of cell-free DNA analysis for fetal trisomy 21 (T21) by shipping the whole blood samples from Europe to a laboratory in the USA.

METHODS

A European multicenter prospective, consecutive cohort study was performed enrolling pregnant women from Sweden and the Netherlands. Blood samples were drawn just prior to a planned of invasive diagnostic procedure in a population at increased risk for fetal T21 and then shipped to the USA without any blood processing. Chromosome-selective sequencing was carried out on chromosome 21 with reporting high risk or low risk of T21. Karyotyping or rapid aneuploidy detection was used as the clinical reference standard.

RESULTS

Of the 520 eligible study subjects, a T21 test result was obtained in 504/520 (96.9%). Risk assessment was accurate in 503/504 subjects (99.8%). There was one false negative result for T21 (sensitivity 17/18, 94.4%, and specificity 100%).

CONCLUSION

This is the first prospective European multicenter study showing that non-invasive prenatal testing using directed sequencing of cell-free DNA applied to blood samples shipped across the Atlantic Ocean, is highly accurate for assessing risk of fetal T21.