Committee Opinion No. 640: Cell-Free Dna Screening For Fetal Aneuploidy

Performance of cell-free DNA testing for common fetal trisomies in triplet pregnancies

OBJECTIVE

In singleton pregnancies, the use of cell-free DNA (cfDNA) analysis as a screening test for common fetal trisomies has spread worldwide though we still lack sufficient data for its use in triplet pregnancies. The objective of this study is to assess the performance of cfDNA testing in detecting fetal aneuploidies in triplet pregnancies as a first-tier test.

METHOD

We performed a retrospective cohort study including data from pregnant women with a triplet pregnancy who underwent cfDNA testing between May 1, 2017, and January 15, 2020. cfDNA was obtained by massive parallel sequencing (VeriSeq NIPT solution; Illumina®). The objectives of the study were to assess the diagnostic performance of cfDNA testing for trisomy 21 (T21) (primary outcome), trisomy 18 (T18) and 13 (secondary outcomes).

RESULTS

During the study period, cfDNA testing was performed in 255 women with triplet pregnancy, of which 165 (64.7%) had a neonatal outcome available. Three tests were positive for T21, one of which was confirmed by an antenatal karyotype, and the other was confirmed at birth. The third case did not undergo an invasive procedure and was not confirmed at birth (false positive). In one case, cfDNA testing was positive for T18 and was confirmed by an antenatal karyotype. There were no cases of trisomy 13 in the cohort. The no-call rate was 2.4% at first sampling. Fifty-eight (22.7%) women had embryo reduction, which in 40 (69%) of whom was performed after the cfDNA test result.

CONCLUSION

cfDNA testing could be offered as primary screening for main fetal aneuploidies in triplet pregnancies after provision of appropriate patient information.

Selection of prenatal screening with nuchal translucency > 95th centile and below 99th centile: a 4-year observational study with real-world data

OBJECTIVE

We sought to analyze the genetic outcomes of fetuses with nuchal translucency (NT) > 95th centile, and determine whether prenatal genetic counseling, chromosomal microarray analysis (CMA) or non-invasive prenatal testing (NIPT) are truly beneficial for the outcomes of fetuses with increased NT > 95th centile and below 99th centile.

MATERIALS AND METHODS

A total of 535 pregnant women were included in this study, with a fetal NT > 95th centile at 11-13+6 weeks of gestation from January 2017 to December 2020. 324 pregnant women with fetal NT > 95th centile and below 99th centile combined with other risk factors and NT > 99th centile received prenatal diagnostic karyotype analysis and CMA, and 211 pregnant women with fetal isolated increased NT > 95th centile and below 99th centile were selected to carry out NIPT.

RESULTS

A total of 211 pregnant women who underwent NIPT were included in the study, NIPT results showed that 8 high-risk cases were confirmed by prenatal diagnosis. Overall, the detection rate of NIPT was 3.79%. A total of 324 pregnant women with fetal NT > 95th centile and below 99th centile, along with other risk factors, and those with fetal NT > 99th centile, received karyotype analysis and CMA for prenatal diagnosis. Among them, a total of 73 genetic abnormalities were detected, including 45 cases of chromosomal aneuploidy, 7 cases of structural abnormalities, and 21 cases of copy number variations (CNVs) with a size of less than 10 Mb. In addition, the 73 women with genetic abnormalities are divided into three groups based on the NT measurement (Group 1: Fetuses with NT > 95th centile and below 99th centile, Group 2: Fetuses with NT > 99th centile, and Group 3: Fetuses with NT > 99th centile). 13.11% (8/61) of pathogenic genetic abnormalities (6 chromosomal aneuploidy, 1 structural abnormality, and 1 likely pathogenic CNV) will be missed if genetic counseling and prenatal genetic testing were not conducted in fetuses with increased NT > 95th centile and below 99th centile combined with other risks. Pathogenic CNVs were the most common abnormalities in group 3, and one likely pathogenic CNV was detected in group 1 and group 3, respectively, and a total of 14 CNVs of unknown clinical significance (VOUS) were detected.

CONCLUSIONS

Through this study, we demonstrated that the critical value of NT > 95th centile for invasive detection or NIPT. Invasive testing combined with CMA may be recommended for fetuses with NT > 95th centile and below 99th centile and with other risks. But when isolated NT > 95th centile and below 99th centile, NIPT would be appropriate.

Impact of a Potential 20-Week Abortion Ban on Likelihood of Completing Required Views in Second-Trimester Fetal Anatomy Ultrasound

OBJECTIVE

The aim of this study was to quantify the likelihood of assessing all mandated fetal views during the second-trimester anatomy ultrasound prior to the proposed federal 20-week abortion ban.

STUDY DESIGN

Retrospective cohort study of a random sample of 1,983 patients undergoing anatomy ultrasound in 2017 at a tertiary referral center. The difference in proportion of incomplete anatomic surveys prior compared with after 20-week gestation was analyzed using X 2 and adjusted logistic regression; difference in mean days elapsed from anomaly diagnosis to termination tested using t-tests and survival analysis.

RESULTS

Incomplete views were more likely with initial ultrasound before 20 weeks (adjusted relative risk: 1.70; 95% confidence interval: 1.50-1.94); 43.5% versus 26.1% were incomplete before and after 20 weeks, respectively. Fetal structural anomalies were identified in 6.4% (n = 127/1,983) scans, with 38.0% (n = 49) identified at follow-up after initial scan was incomplete. 22.8% (n = 29) with an anomaly terminated.

CONCLUSION

A complete assessment of fetal views during an anatomy ultrasound prior to 20-week gestation is often not technically feasible. Legislation limiting abortion to this gestational age would greatly impact patient's ability to make informed choices about their pregnancies.

KEY POINTS

· It is often not technically possible to complete anatomy ultrasound prior to 20-week gestation.. · Often, anomalies are missed during early, incomplete anatomy ultrasounds.. · After the diagnosis of a structural anomaly, one in five chose to terminate the pregnancy..

Residual risk of clinically significant copy number variations in fetuses with nasal bone absence or hypoplasia after excluding non-invasive prenatal screening-detectable findings

BACKGROUND

It remains controversial whether prenatal screening or diagnostic testing should be offered to fetuses with nasal bone (NB) absence or hypoplasia, and there are no studies comparing the yield of chromosomal microarray analysis (CMA) to non-invasive prenatal screening (NIPS). The aim of this study was to evaluate the residual risk of clinically significant copy number variations (CNVs) in fetuses with NB absence or hypoplasia after excluding theoretically NIPS-detectable abnormalities, and to assess their clinical outcomes.

METHODS

This prospective study encompassed 400 fetuses with NB absence or hypoplasia undergoing CMA testing between 2015 and 2022. Clinically significant CMA findings were categorized into three subgroups, including three-NIPS-detectable (trisomies 21, 18 and 13), five-NIPS-detectable (trisomies 21, 18 and 13 and sex chromosome aneuploidies) and genome-wide NIPS-detectable (variants over 7 Mb). We calculated the theoretical residual risk and compared it with the results of a control cohort of low-risk pregnancies. We further evaluated their clinical outcomes.

RESULTS

The overall diagnostic yield in our cohort was 7.8% (31/400). The detection rate of clinically significant CMA findings in fetuses with non-isolated NB absence or hypoplasia was significantly higher than that in fetuses with isolated NB absence or hypoplasia (20.0% vs. 6.6%, P =.005). The theoretical residual risks in all NIPS models were significantly higher when compared with the control cohort. The normal infant rate in fetuses with normal CMA results was 97.9% (323/330), and a significant higher incidence was observed in fetuses with isolated NB absence or hypoplasia compared with non-isolated NB absence or hypoplasia (98.4% vs. 91.7%, P =.028).

CONCLUSIONS

The residual risk of clinically significant CNVs in fetuses with NB absence or hypoplasia following the exclusion of theoretically NIPS-detectable findings was higher than that in low-risk pregnancies. This risk should be considered in genetic counseling to make a more comprehensive and precise choice regarding prenatal genetic testing.

Reconsidering the use of race adjustments in maternal serum screening

The use of race in maternal serum screening is problematic because race is a social construct rather than a distinct biological classifier. Nevertheless, laboratories offering this testing are encouraged to use race-specific cutoff values for maternal serum screening biomarkers to determine the risk of fetal abnormalities. Large cohort studies examining racial differences in maternal serum screening biomarker concentrations have yielded conflicting results, which we postulate may be explained by genetic and socioeconomic differences between racial cohorts in different studies. We recommend that the use of race in maternal serum screening should be abandoned. Further research is needed to identify socioeconomic and environmental factors that contribute to differences in maternal serum screening biomarker concentrations observed between races. A better understanding of these factors may facilitate accurate race-agnostic risk estimates for aneuploidy and neural tube defects.

Association between chromosome abnormities and prenatal diagnosis indicators screening in the second trimester of pregnancy

This study aimed to explore the prenatal indicators in the second trimester of pregnancy and their association with chromosome abnormities (CA) to guide decisions toward invasive diagnostic procedures. Pregnant women who underwent prenatal screening and underwent amniocentesis in the second trimester in our Hospital between June 2017 and February 2019 were included in this retrospective cohort study. The reason for amniocentesis in prenatal screening and diagnoses was extracted from the charts. Finally, 3449 pregnant women were included. Of them, 181 were with CA confirmed by amniocentesis (i.e., the CA group), while 3268 were without CA (i.e., the non-CA group). Compared with the women in the non-CA group, those in the CA group were more likely to be older (30 [27,32] vs 29 [26,31], P < .001), had higher gestational weeks (20 [19,23] vs 19 [18,23], P = .008), an increased risk of advanced maternal age (AMA) (9.4% vs 2.2%, P < .001), had an increased risk of NIPT (IRN) (5.1% vs 1.9%, P < .001), had higher rates of a parental chromosome abnormality (PCA) (1.8% vs 0.9%, P = .002), and had increased risk of trisomy 21 (IRT21) (63.0% vs 45.3%, P < .001). AMA (OR = 4.22, 95% CI: 2.35-7.58, P < .001; AUC = 0.536), IRN (OR = 10.62, 95% CI: 6.66-16.94, P < .001; AUC = 0.589), PCA (OR = 4.77, 95% CI: 2.01-11.32, P < .001; AUC = 0.584), and IRT21 (OR = 0.67, 95% CI: 0.47-0.89, P = .008; AUC = 0.515) were independently associated with CA. AMA, IRN, IRT21, and PCA during the second trimester were independently associated with CA, but their predictive values for CA were relatively low. Combining those indicators may improve the predictive value.

Prediction of Pregnancy-Associated Hypertension Using a Scoring System: A Multicenter Cohort Study

This study aimed to develop an early pregnancy risk scoring model for pregnancy-associated hypertension (PAH) based on maternal pre-pregnancy characteristics, such as mean arterial pressure (MAP), pregnancy-associated plasma protein-A (PAPP-A) or neither. The perinatal databases of seven hospitals from January 2009 to December 2020 were randomly divided into a training set and a test set at a ratio of 70:30. The data of a total pregnant restricted population (women not taking aspirin during pregnancy) were analyzed separately. Three models (model 1, pre-pregnancy factors only; model 2, adding MAP; model 3, adding MAP and PAPP-A) and the American College of Obstetricians and Gynecologists (ACOG) risk factors model were compared. A total of 2840 (8.11%) and 1550 (3.3%) women subsequently developed PAH and preterm PAH, respectively. Performances of models 2 and 3 with areas under the curve (AUC) over 0.82 in both total population and restricted population were superior to those of model 1 (with AUCs of 0.75 and 0.748, respectively) and the ACOG risk model (with AUCs of 0.66 and 0.66) for predicting PAH and preterm PAH. The final scoring system with model 2 for predicting PAH and preterm PAH showed moderate to good performance (AUCs of 0.78 and 0.79, respectively) in the test set. "A risk scoring model for PAH and preterm PAH with pre-pregnancy factors and MAP showed moderate to high performances. Further prospective studies for validating this scoring model with biomarkers and uterine artery Doppler or without them might be required".

A Case Report of a Feto-Placental Mosaicism Involving a Segmental Aneuploidy: A Challenge for Genome Wide Screening by Non-Invasive Prenatal Testing of Cell-Free DNA in Maternal Plasma

Non-invasive prenatal testing (NIPT) using cell-free DNA can detect fetal chromosomal anomalies with high clinical sensitivity and specificity. In approximately 0.1% of clinical cases, the NIPT result and a subsequent diagnostic karyotype are discordant. Here we report a case of a 32-year-old pregnant patient with a 44.1 Mb duplication on the short arm of chromosome 4 detected by NIPT at 12 weeks' gestation. Amniocentesis was carried out at 18 weeks' gestation, followed by conventional and molecular cytogenetic analysis on cells from the amniotic fluid. SNP array analysis found a de novo deletion of 1.2 Mb at chromosome 4, and this deletion was found to be near the critical region of the Wolf-Hirschhorn syndrome. A normal 46,XY karyotype was identified by G-banding analysis. The patient underwent an elective termination and molecular investigations on tissues from the fetus, and the placenta confirmed the presence of type VI true fetal mosaicism. It is important that a patient receives counselling following a high-risk call on NIPT, with appropriate diagnostic analysis advised before any decisions regarding the pregnancy are taken. This case highlights the importance of genetic counselling following a high-risk call on NIPT, especially in light of the increasing capabilities of NIPT detection of sub-chromosomal deletions and duplications.

Neonatal mortality and morbidity in Down syndrome in the time of prenatal aneuploidy testing: a retrospective cohort study

The total uptake of prenatal aneuploidy screening for Down syndrome (DS) is increasing worldwide. As a result of increasing prenatal diagnosis of DS and subsequent termination of pregnancy, livebirth prevalence of DS is decreasing. The aim of this study is to explore the impact of an increasing uptake of prenatal aneuploidy screening on the neonatal mortality and morbidity in DS. This is a retrospective cohort study of 253 neonates with DS born between 2012 and 2018 that were seen at the outpatient clinic of five hospitals in the Netherlands. The medical files were reviewed for maternal and neonatal characteristics and neonatal morbidities. The Dutch national birth registry (Perined) provided mortality numbers of neonates with DS. The results were interpreted in the context of other published studies. Neonatal mortality in DS remained stable, ranging from 1.4 to 3.6%. A congenital heart defect (CHD) was found in 138 of the 251 neonates (55.0%) with atrial septal defect, atrioventricular septal defect, and ventricular septal defect being the most common. The type of CHD in DS did not change over time. Gastro-intestinal defects were present in 22 of the 252 neonates with DS (8.7%), with duodenal atresia as the most reported anomaly. Persistent pulmonary hypertension of the neonate (PPHN) was found in 31 of the 251 infants (12.4%).  Conclusions: Although uptake of prenatal aneuploidy screening increased, neonatal mortality and morbidity in DS appears to be stable. An increased incidence of PPHN was found. What is Known: • The total uptake of prenatal aneuploidy screening for Down syndrome is increasing worldwide. • As a result of increasing prenatal diagnosis of Down syndrome and subsequent termination of pregnancy, the livebirth prevalence of Down syndrome is decreasing. What is New: • Although uptake of prenatal aneuploidy screening increased, neonatal mortality and morbidity in Down syndrome appears to be stable. • An increased incidence of persistent pulmonary hypertension of the neonate was found.

Tricky TRIC: A replication study using trophoblast retrieval and isolation from the cervix to study genetic birth defects

OBJECTIVE

Noninvasive Prenatal Diagnosis has recently been introduced for a limited number of monogenetic disorders. However, the majority of DNA diagnostics still require fetal material obtained using an invasive test. Recently, a novel technique, TRIC (Trophoblast Retrieval and Isolation from the Cervix), has been described, which collects fetal trophoblast cells by endocervical sampling. Since this technique has not been successfully replicated by other groups, we aimed to achieve this in the current study.

METHOD

Pregnant women referred for transvaginal chorionic villous sampling (CVS) were asked for an endocervical sample prior to CVS. The TRIC samples were processed to isolate trophoblast DNA. TRIC DNA was used in ForenSeq to determine the amount of maternal DNA contamination, and for Sanger sequencing in case of a monogenic disorder.

RESULTS

23%-44% of samples had a sufficiently high fetal DNA fraction to allow genetic testing, as calculated by Sanger sequencing and ForenSeq, respectively.

CONCLUSION

We have been able to successfully replicate the TRIC protocol, although with a much lower success rate as described by the original study performing TRIC. As we obtained the samples in the actual clinical setting envisioned, the method in its current setup is not advisable for use in prenatal diagnostics.

Factors associated with US and Canadian genetic counselors' testing decisions during pregnancy

Decision-making regarding prenatal screening and diagnostic testing has become more complex as the number of options has increased, with pregnant patients having access to more information about their pregnancies than ever before. Genetic counselors have extensive training in prenatal genetic screening and testing options, but personal decision-making in this well-informed population remains largely unstudied. This study describes the prenatal testing decisions genetic counselors made during their own pregnancies, and the factors identified as important when making those decisions. A web-based, mixed-methods survey was distributed to members of multiple professional societies for genetic counselors. A total of 318 genetic counselors across numerous specialties in the United States and Canada participated in this study. The satisfaction with decision scale was modified and applied to measure participants' decisional satisfaction. In their most recent pregnancies, most genetic counselors pursued carrier screening (77%) and aneuploidy and/or open neural tube defect screening (88%). A minority of genetic counselors (15%) utilized diagnostic testing. Common factors considered when making testing decisions included wanting information that could impact future decisions, test specifics (e.g., accuracy, methodology, and content), and knowledge gained from participants' genetic counseling background. The uptake of diagnostic testing among prenatal genetic counselors was significantly greater (p < 0.05) than the uptake among genetic counselors in other specialties. This informed study population largely self-directed their own prenatal care, leading to high satisfaction with their decisions. Data in this study provide evidence for promoting participation in prenatal screening and testing decision-making to maximize decisional satisfaction.

Comparison of noninvasive prenatal screening for defined pathogenic microdeletion/microduplication syndromes and nonsyndromic copy number variations: a large multicenter study

Background: This retrospective study assessed the precision of noninvasive prenatal testing (NIPT) in detecting microdeletion/microduplication syndromes (MMSs) and nonsyndromic copy number variations (CNVs). Methods: The study included 19,086 singleton pregnancies screened on NIPT using high-throughput sequencing. Pregnancies with CNVs on NIPT underwent amniocentesis for karyotyping and CNV sequencing (CNV-seq). We analyzed pathogenic MMSs and nonsyndromic CNVs separately, dividing the CNVs into subgroups based on fragment size and fetal ultrasound findings. Results: A total of 170 abnormalities were detected by NIPT, of which 113 (66.5%) underwent invasive testing. The positive predictive value (PPV) of CNV-seq for all types of CNV detected by NIPT was 35.4%, with PPVs of 61.5 and 27.6% for pathogenic MMSs and nonsyndromic CNVs, respectively. PPVs for NIPT showed different values depending on gestational characteristics, with the highest PPV for NIPT in the group with increased nuchal thickness (66.7%) and for the abnormal ultrasound group (57.1%). CNVs ≤5 Mb with normal ultrasound findings were generally associated with a healthy fetus. Conclusion: NIPT can detect chromosomal aberrations in the first trimester, with high performance for MMSs. However, due to the low PPV for nonsyndromic CNVs, and the good pregnancy outcome in most cases, the introduction of expanded NIPT would cause an increase in unnecessary invasive procedures and inappropriate terminations of pregnancy.

Clinical experience of noninvasive prenatal testing for rare chromosome abnormalities in singleton pregnancies

Objectives: The study aimed to investigate the clinical use of noninvasive prenatal testing (NIPT) for common fetal aneuploidies as a prenatal screening tool for the detection of rare chromosomal abnormalities (RCAs).

Methods: Gravidas with positive NIPT results for RCAs who subsequently underwent amniocentesis for a single nucleotide polymorphism array (SNP array) were recruited. The degrees of concordance between the NIPT and SNP array were classified into full concordance, partial concordance, and discordance. The positive predictive value (PPV) was used to evaluate the performance of NIPT.

Results: The screen-positivity rate of NIPT for RCAs was 0.5% (842/158,824). Of the 528 gravidas who underwent amniocentesis, 29.2% (154/528) were confirmed to have positive prenatal SNP array results. PPVs for rare autosomal trisomies (RATs) and segmental imbalances were 6.1% (7/115) and 21.1% (87/413), respectively. Regions of homozygosity/uniparental disomy (ROH/UPD) were identified in 9.5% (50/528) of gravidas. The PPV for clinically significant findings was 8.0% (42/528), including 7 cases with mosaic RATs, 30 with pathogenic/likely pathogenic copy number variants, and 5 with imprinting disorders.

Conclusion: NIPT for common fetal aneuploidies yielded low PPVs for RATs, moderate PPVs for segmental imbalances, and incidental findings for ROH/UPD. Due to the low PPV for clinically significant findings, NIPT for common fetal aneuploidies need to be noticed for RCAs.

Non-invasive prenatal testing for the detection of trisomy 13, 18, and 21 and sex chromosome aneuploidies in 68,763 cases

Objectives: Non-invasive prenatal testing (NIPT) has been widely used in recent years. According to clinical experience from all hospitals providing prenatal screening services in Beijing, we explored the feasibility of using NIPT for the analysis of common foetal aneuploidies among pregnancies.

Methods: In total, 68,763 maternal blood samples were collected from January 2020 to December 2020 at the Beijing prenatal diagnosis agency. Cases with positive screening results by NIPT detection were validated using prenatal diagnosis.

Results: In total, 920 cases had a high-risk NIPT result, and 755 cases were shown to be truly positive by a chromosome karyotyping analysis; the prenatal diagnosis rate was 82.07% (755/920). Of the920 cases, there were 164 cases of T21, 70 cases of T18, 38 cases of T13, 360 cases of SCAs and 288 cases of other chromosomal abnormalities. The positive rates of T21, T18, T13, and SCAs were 0.24% (164/68,763), 0.10% (70/68,763), 0.06% (38/68,763) and 0.52% (360/68,763), respectively. The sensitivity and specificity were 98.17% and 99.92% for T21, 96.15% and 99.93% for T18, and 100% and 99.95% for T13, respectively. The PPVs of T21,T18,T13 and SCAs were65.24% (107/164), 35.71% (25/70), 18.42% (7/38) and 31.39% (113/360), respectively. For all indications, there were more higher T21/18/13 in the high-risk group than in the low-risk group (comprising only cases of voluntary request), with a positive rate of 0.46% vs. 0.27% (p < 0.001), sensitivity of 99.16% vs. 91.30% (p = 0.02) and PPV of 56.73%vs.32.81% (p = 0.001), but there was no significant difference in specificity between the groups (p = 0.71). The detection indication with the highest PPV (100%) by NIPT was ultrasound structural abnormalities and ultrasound soft marker abnormalities for T21 and ultrasound structural abnormalities and NT thickening for T18 and T13. The PPVs of different clinical indications of T21 (p = 0.002), T13 (p = 0.04) and SACs (p = 0.02) were statistically significant.

Conclusion: The high specificity, efficiency and safety (non-invasiveness) of NIPT can effectively improve the detection rate of common chromosomal aneuploidy, thereby reducing the occurrence of birth defects. We should encourage pregnant women with NIPT-high-risk results to undergo a prenatal diagnosis to determine whether the foetus has chromosomal abnormalities. More importantly, the screening efficiency of NIPT in the low-risk group was significantly lower than that in the high-risk group. Therefore, the use of NIPT in low-risk groups should be fully promoted, and socioeconomic benefits should be considered.

Análisis de concordancia entre la prueba prenatal no invasiva (NIPT) y el cariotipo prenatal para la detección de aneuploidías fetales

Introducción. La prueba prenatal no invasiva (NIPT, por su sigla en inglés) es una prueba de tamización de aneuploidías fetales con una mayor sensibilidad y especificidad que la tamización bioquímica prenatal tradicional. Objetivo. Evaluar la concordancia entre la NIPT y el cariotipo prenatal para la detección de aneuploidías fetales en embarazos de alto riesgo de dichas anomalías Materiales y métodos. Estudio piloto prospectivo realizado entre septiembre de 2019 y diciembre de 2020 en 20 pacientes con gestaciones clasificadas como de alto riesgo para aneuploidías fetales con base en los hallazgos ecográficos y atendidas en Bogotá y Medellín, Colombia. A cada paciente se le realizó una NIPT y una prueba invasiva confirmatoria (cariotipo prenatal). La concordancia entre ambos métodos se determinó mediante el coeficiente kappa de Cohen (nivel de significancia p<0.05), donde valores >0.7 se consideraron como un buen nivel de concordancia. Resultados. En 3 de las 20 gestaciones (15%) se detectaron aneuploidías mediante estudio citogenético invasivo: trisomía 21, trisomía 18 y monosomía X. La NIPT detectó la trisomía 21 y la monosomía X, pero falló en detectar la trisomía 18. Respecto al análisis de concordancia, el coeficiente de kappa de Cohen entre la NIPT y cariotipo prenatal fue 0.77, 1.0 y 0 para trisomía 21, monosomía X, trisomía 18, respectivamente. Además, la NIPT detectó 67% de las aneuploidías. Conclusión. En el presente estudio, primero en realizarse en Colombia, se observó una buena concordancia entre la NIPT y la prueba invasiva (cariotipo prenatal) para la detección de aneuploidías. Sin embargo, los resultados aquí reportados enfatizan la recomendación de utilizar la NIPT como prueba de tamización y no como prueba diagnóstica.

Knowledge and attitude of pregnant women in the Kingdom of Saudi Arabia toward Noninvasive prenatal testing: A single center study

Background

Noninvasive prenatal testing (NIPT) is a screening tool for chromosomal aneuploidies. Prior knowledge of NIPT is an inherent factor in the decision‐making process. We assessed the knowledge and attitude of pregnant women related to prenatal testing with a particular focus on NIPT.

Methods

A prospective cross‐sectional study, using a culturally validated questionnaire, was conducted with 342 pregnant women of whom 74.9% consented for prenatal screening. Mean age and gestational weeks ± standard deviation was 31 ± 5 and 26 ± 11, respectively.

Results

A positive/very positive attitude was observed to ultrasound, followed by FCT, NIPT, and lastly to CVS. More than half of the participants (56.1%) had no previous knowledge of NIPT. A reaching significance association was detected between education and knowledge of NIPT. Significant association was detected between risk for aneuploidy and knowledge of NIPT. The majority (74%) indicated their willingness to perform the test. The effect and value of society on the pregnant women to make a decision regarding NIPT was negligible.

Conclusion

The pregnant women in the current study displayed a lack of knowledge and awareness regarding prenatal screening, particularly the NIPT. We recommend that pregnant women receive adequate counseling regarding prenatal screening to increase their awareness and knowledge of prenatal testing, including NIPT.

Modified multiple marker aneuploidy screening as a primary screening test for preeclampsia

Background

Abnormal levels of maternal biochemical markers used in multiple marker aneuploidy screening have been associated with adverse pregnancy outcomes. This study aims to assess if a combination of maternal characteristics and biochemical markers in the first and second trimesters can be used to screen for preeclampsia (PE). The secondary aim was to assess this combination in identifying pregnancies at risk for gestational hypertension and preterm birth.

Methods

This case-control study used information on maternal characteristics and residual blood samples from pregnant women who have undergone multiple marker aneuploidy screening. The median multiple of the median (MoM) of first and second trimester biochemical markers in cases (women with PE, gestational hypertension and preterm birth) and controls were compared. Biochemical markers included pregnancy-associated plasma protein A (PAPP-A), placental growth factor (PlGF), human chorionic gonadotropin (hCG), alpha feto-protein (AFP), unconjugated estriol (uE3) and Inhibin A. Logistic regression analysis was used to estimate screening performance using different marker combinations. Screening performance was defined as detection rate (DR) and false positive rate (FPR). Preterm and early-onset preeclampsia PE were defined as women with PE who delivered at < 37 and < 34 weeks of gestation, respectively.

Results

There were 147 pregnancies with PE (81 term, 49 preterm and 17 early-onset), 295 with gestational hypertension, and 166 preterm birth. Compared to controls, PE cases had significantly lower median MoM of PAPP-A (0.77 vs 1.10, p < 0.0001), PlGF (0.76 vs 1.01, p < 0.0001) and free-β hCG (0.81 vs. 0.98, p < 0.001) in the first trimester along with PAPP-A (0.82 vs 0.99, p < 0.01) and PlGF (0.75 vs 1.02, p < 0.0001) in the second trimester. The lowest first trimester PAPP-A, PlGF and free β-hCG were seen in those with preterm and early-onset PE. At a 20% FPR, 67% of preterm and 76% of early-onset PE cases can be predicted using a combination of maternal characteristics with PAPP-A and PlGF in the first trimester. The corresponding DR was 58% for gestational hypertension and 36% for preterm birth cases.

Conclusions

Maternal characteristics with first trimester PAPP-A and PlGF measured for aneuploidy screening provided reasonable accuracy in identifying women at risk of developing early onset PE, allowing triage of high-risk women for further investigation and risk-reducing therapy. This combination was less accurate in predicting women who have gestational hypertension or preterm birth.

Retrospective analysis of the risk factors associated with failure in obtaining effective noninvasive prenatal test results and pregnancy outcomes: a case-control study

OBJECTIVE

: To explore the pregnancy outcomes of women who could not obtain effective results from noninvasive prenatal testing (NIPT) and examine the factors leading to test failure.

METHODS

: From April 2017 to December 2019, 120,041 pregnant women enrolled for voluntary NIPT. The case group comprised of 274 (274/120,041) women who failed to obtain effective NIPT results, and the control group (n = 540) was from the same population who obtained effective NIPT results and matched by age at a 1:2 ratio. Abnormal pregnancy rates between the two groups were analyzed using Chi-square analysis. NIPT failure risk factors were analyzed using logistic regression analysis.

RESULTS

: Logistic regression analysis showed that increased maternal age (OR=0.988; 95% CI = 0.982-0.994), increased pregnancy age (OR=0.989; 95%CI = 0.988-0.991), and decreased cell-free fetal DNA concentration (OR=1.050; 95%CI=1.043-1.058) were independent risk factors for NIPT failure. 15 cases showed fetus loss in cases of NIPT failure. There was a significant difference in abnormal pregnancy rate between the NIPT success and failure groups (χ2 = 50.943, P < 0.05).

CONCLUSION

: The specific interventions, guidance, and precautions are needed for pregnant women during perinatal period, especially those who have no effective NIPT results.

Prenatal Genetic Screening and Diagnostic Testing: Assessing Patients' Knowledge, Clinical Experiences, and Utilized Resources in Comparison to Provider's Perceptions

Objective  This survey study aimed to assess patient knowledge, clinical resources, and utilized resources about genetic screening and diagnostic testing. Study Design  A one-time anonymous paper survey was distributed to 500 patients at a major urban obstetrics and gynecology department, and an online survey was sent to 229 providers. Descriptive statistics and chi-squared analyses were performed. Results  In all, 466 of 500 patient surveys were completed, and 441 analyzed (88.2% response rate). Among providers, 66 of 229 (29.0% response rate) responded. Patients were on average 32 years old, 27 weeks pregnant, and most often reported a graduate degree level of education (47.4%). Over 75% of patients reported accurate knowledge of basic genetic statements. Patients reported that discussing screening and diagnostic testing with their provider was significantly associated with properly defining screening and diagnostic testing ( p  < 0.001). Less than 10% of patients reported providers distributing web/video links, books, or any other resource; however, patients most often independently accessed web links (40.1%). Conclusion  Our findings suggest a positive impact from patient and provider discussions in office on patient knowledge and understanding. Discrepancies between educational resources distributed in the clinic and individually accessed resources highlight possible areas of change. Future work should evaluate and implement differing resources to increase patient knowledge.

What are the ethical issues involved in noninvasive prenatal testing in Japan?

AIMS

Noninvasive prenatal testing (NIPT) of pregnant women has been performed worldwide since 2011, and it is currently performed in more than 90 countries. However, the rate of adoption in Japan remains at less than 2%. This review seeks to identify the ethical and practical issues surrounding noninvasive prenatal screening-including the purpose of the test, its pros and cons, issues surrounding fair treatment, and social factors-to better understand why the adoption rate remains low.

METHODS

This study examines the complex ethical issues surrounding noninvasive prenatal testing, including the purpose of the test, its pros and cons, issues related to fair treatment, and social factors.

RESULTS

Although cell-free DNA analysis for common fetal trisomies using maternal blood is highly accurate, lack of access to such testing and discriminatory attitudes in society remain important barriers. Personal choices such as whether to undergo noninvasive prenatal screening and whether to continue a pregnancy are sometimes criticized by those who believe that it leads to the "selection of life" or discrimination against people with disabilities.

CONCLUSIONS

Obstetrics has changed dramatically in recent years, and prenatal diagnosis technology has also advanced. To keep up with these advances, better information should be provided to ensure the public has a more nuanced understanding of the screening beyond the overused argument that it leads to "selection of life."

Genetic counseling for congenital heart disease - Practice resource of the national society of genetic counselors

Congenital heart disease (CHD) is an indication which spans multiple specialties across various genetic counseling practices. This practice resource aims to provide guidance on key considerations when approaching counseling for this particular indication while recognizing the rapidly changing landscape of knowledge within this domain. This resource was developed with consensus from a diverse group of certified genetic counselors utilizing literature relevant for CHD genetic counseling practice and is aimed at supporting genetic counselors who encounter this indication in their practice both pre- and postnatally.

Privacy Risks in Prenatal Aneuploidy and Carrier Screening: What Obstetricians and Their Patients Need to Know

Modern prenatal genetic screening techniques such as cell-free fetal DNA and expanded carrier screening genotype substantial amounts of maternal and fetoplacental DNA. Although DNA can be deidentified by stripping protected health information from genetic data, anonymized DNA can be reidentified using genetic databases, raising long-term genetic privacy concerns for both mother and fetus. In this commentary, we explore the evolution of prenatal genetic screening and how modern screening techniques may pose unanticipated privacy risks. We highlight knowledge gaps and outline steps to improve patient awareness of and control over their genetic privacy, including specific recommendations for laboratories and prenatal care practitioners who offer screening. We also encourage our colleagues who provide prenatal care to be well informed about the privacy implications of the genetic tests we order and to be vocal advocates for our patients' genetic privacy, both with the laboratories that perform these tests and in the public sphere.

Evaluation of the practical applications of fluorescence in situ hybridization in the prenatal diagnosis of positive noninvasive prenatal screenings

OBJECTIVE

To investigate the application value and limitations of fluorescence in situ hybridization (FISH) in prenatal diagnosis of positive results for trisomies 13, 18, 21 (T13, T18, T21) and sex chromosome aneuploidies (SCAs) indicated by noninvasive prenatal screening (NIPS).

METHODS

Samples from women who underwent prenatal diagnosis for the indication of positive NIPS of T13, T18, T21, and SCAs were collected. Each sample was split into two for both karyotype analysis and FISH analysis. The efficiency and consistency of FISH were assessed for the detection of chromosome abnormalities in the indications of positive NIPS results compared with karyotyping.

RESULTS

A total of 649 pregnant women who scored positive for clinical significance of fetal chromosome abnormalities by NIPS were enrolled in our study, including T 13 (6%), T18 (14.3%), T21 (44.7%), SCAs (35.0%). From the following diagnostic test, the positive predictive value (PPV) of NIPS for T13, T18, T21, and SCAs was 17.9, 60.2, 89.3, and 43.6% respectively. FISH analysis was successful in all samples. Compared with karyotyping, the sensitivity and specificity were 98.3 and 100%, respectively. 95.7% (621/649) were fully concordant with karyotyping. 3.2% (21/649) cases were incompletely concordant with the karyotyping, among these cases, the FISH analysis identified all the aneuploidies, but karyotyping analysis provided more information about the chromosomal structure. There were 7 cases (1.1%, 7/649) of anomalies diagnosed by karyotype but missed out by FISH, all of which occurred in cases with the indication of SCAs. If the indications were confined to cases with a positive NIPS of T13, T18, T21, the diagnostic consistency of the two methods almost perfectly agree, and all the aneuploidies were detected by the FISH assay. FISH analysis was highly consistent in determining whether the fetus was euploid or not in the prenatal diagnosis for the patients with positive NIPS results compared with karyotyping (kappa= 0.976, p < .01).

CONCLUSION

For the prenatal diagnostic indications of positive NIPS of T13, T18, T21, and SCAs, FISH was equally efficacious in identifying aneuploidies and provided a quick diagnosis to alleviate anxiety. However, the missed risk of FISH analysis for structural chromosomal abnormalities should be taken seriously and fully informed during genetic counseling.

Contingent prenatal screening for frequent aneuploidies with cell-free fetal DNA analysis

OBJECTIVE

To analyze the results of contingent screening for common aneuploidies at our center from June 2017 to June 2019.

MATERIALS AND METHODS

Traditional screening tests were performed using a combination of biochemical markers and ultrasound measurements in the first and second trimesters to assess the risk of trisomies 21 (T21), 18 (T18) and 13 (T13). Cell-free DNA (cf-DNA) testing was offered (Harmony test) to pregnant women at high risk (>1/280 for T21 and > 1/150 for T13 and T18) and a normal early morphology scan. In positive cases, prenatal sampling was strongly recommended to confirm the results by gold standard methods (QF-PCR and karyotyping). Newborns' phenotypes were corroborated after birth in all cases.

RESULTS

In this prospective study, 8153 pregnant women were enrolled, resulting in 390 at high risk according to traditional screening tests. cfDNA testing was offered to 383 women. Traditional screening tests showed a false negative rate of 9.68% for T21. Traditional test sensitivity for T21 was 90.3%, for a false positive rate of 4.17% and a positive predictive value of 7.6%. The positive and negative predictive value for cfDNA testing was 100%. The approach used avoided invasive procedures in 91.3% of women at high risk. The prevalence of chromosomal abnormalities in the population analyzed was 1 in 164, and 1 in 210 for T21.

CONCLUSIONS

Our results show that offering cf-DNA testing to women at high risk in traditional tests (including those with risks >1 in 50) significantly reduces false positives and, therefore, the number of invasive tests. Extending the use of cf-DNA testing to intermediate risk categories may be cost effective.

Does non-invasive prenatal testing affect the livebirth prevalence of Down syndrome in the Netherlands? A population-based register study

Objective

To evaluate if non‐invasive prenatal testing (NIPT) affects livebirth (LB) prevalence of Down syndrome (DS) in the Netherlands.

Method

Data from clinical genetics laboratories and the Working Party on Prenatal Diagnosis and Therapy (2014–2018) and previous published data (1991–2013) were used to assess trends for DS LB prevalence and reduction percentage (the net decrease in DS LBs resulting from selective termination of pregnancies). Statistics Netherlands provided general population data.

Results

DS LB prevalence increased from 11.6/10,000 in 1991 to 15.9/10,000 in 2002 (regression coefficient 0.246 [95% CI: 0.105–0.388; p = 0.003]). After 2002, LB prevalence decreased to 11.3/10,000 in 2014 and further to 9.9/10,000 in 2018 (regression coefficient 0.234 (95% CI: −0.338 to −0.131; p < 0.001). The reduction percentage increased from 26% in 1991 to 55.2% in 2018 (regression coefficient 0.012 (95% CI: 0.010–0.013; p < 0.001)). There were no trend changes after introducing NIPT as second‐tier (2014) and first‐tier test (2017).

Conclusions

Introducing NIPT did not change the decreasing trend in DS LB prevalence and increasing trend in reduction percentage. These trends may be caused by a broader development of more prenatal testing that had already started before introducing NIPT.

What's already known about this topic?

The introduction of NIPT changed the landscape in prenatal screening worldwide.

No long‐term population‐based study on the impact of NIPT on DS LB prevalence has been published.

What does this study add?

This study shows how to calculate DS LB prevalence in the absence of a national registration program.

Introducing NIPT caused no trend changes in DS LB prevalence and reduction percentage in the Netherlands.

Noninvasive prenatal testing in women undergoing in vitro fertilization with preimplantation genetic testing

PURPOSE OF REVIEW

To discuss the utilization, performance, and interpretation of noninvasive prenatal testing (NIPT) results in women achieving pregnancy through in vitro fertilization (IVF) and preimplantation genetic testing for aneuploidy (PGT-A).

RECENT FINDINGS

Although PGT-A is a highly accurate method for the selection of euploid embryos the possibility for error still exists. Many women pursue NIPT after conception via IVF with or without PGT-A, whereas some forgo prenatal screening all together. Recent evidence suggests that the prevalence of a positive NIPT following PGT-A is low, and the positive predictive value is altered in this population.

SUMMARY

NIPT is a valuable prenatal screening tool that should be offered to pregnant women regardless of prior PGT. In women who conceive following IVF and PGT-A through the transfer of euploid embryos, positive test results should be interpreted with caution.

Follow-up in Patients With Non-invasive Prenatal Screening Failures: A Reflection on the Choice of Further Prenatal Diagnosis

Background

Our aim was to provide a theoretical basis for clinicians to conduct genetic counseling and choose further prenatal diagnosis methods for pregnant women who failed non-invasive prenatal screening (NIPS).

Methods

A retrospective analysis was performed on pregnant women who had failed NIPS tests.

Results

Among the 123,291 samples, 394 pregnant women did not obtain valid results due to test failures. A total of 378 pregnant women were available for follow-up, while 16 patients were lost to follow-up. Of these 378, 135 pregnant women chose further prenatal diagnosis through amniocentesis, and one case of dysplasia was recalled for postpartum chromosome testing. The incidence rate of congenital chromosomal abnormalities in those who failed the NIPS was 3.97% (15/378), which was higher than that of the chromosomal abnormalities in the common population (1.8%). Among the pregnant women who received prenatal diagnosis, the positive rates of chromosomal abnormalities in the chromosomal microarray analysis/copy number variation sequencing (CMA/CNV-seq) group and in the karyotyping group were 15.28 and 4.76%, respectively.

Conclusion

Prenatal diagnosis should be strongly recommended in posttest genetic counseling for pregnant women with NIPS failures. Further, high-resolution detection methods should be recommended for additional prenatal diagnoses.

The application of expanded noninvasive prenatal screening for genome-wide chromosomal abnormalities and genetic counseling

OBJECTIVE

To evaluate the clinical application of expanded noninvasive prenatal screening (eNIPS) for genome-wide large copy number variation (CNV), i.e. chromosomal deletion/duplication >5 Mb, and aneuploidy; also to provide practical information for counseling eNIPS positive cases.

METHOD

We recruited 34,620 women with singleton pregnancy for genome-wide cell-free plasma DNA sequencing. Screening positive cases were verified by karyotyping and/or SNP array.

RESULT

A total of 461 (1.33%) positive cases were identified through our cfDNA screening including 209 cases of common trisomies (0.60%), 124 cases of sex chromosomal abnormalities (SCA) (0.36%), 71 cases of other autosomal anueploidies (OAA) (0.21%), and 57 CNVs larger than 5 Mb (0.16%). The predictive positive values (PPV) were 70.06% in general for common trisomies with as high as 91.67% for Trisomy21 (T21), 40.22% in general for SCAs with as high as 100% for Jacob Syndrome (XYY). The PPV for OAAs was 5.45%, and T7/T8/T16/T22 were the most frequent OAAs (n = 15, 9, 9, 8, respectively). The PPV for CNVs larger than 5 Mb was 51.22% (n = 57) with the CNV mostly detected on Chr5/Chr4/Chr2/Chr7 (n = 10, 8, 5, 5, respectively).

CONCLUSION

The expanded NIPS had shown promising PPVs for CNVs (large than 5 Mb), SCAs and common trisomies, yet this method required higher efficacy in screening for OAAs. The post-test genetic counseling for expanded NIPS should be tailored to the types of positive cases and also address the origin of abnormal signals (fetal vs. maternal).

Use of amplicon-based sequencing for testing fetal identity and monogenic traits with Single Circulating Trophoblast (SCT) as one form of cell-based NIPT

A major challenge for cell-based non-invasive prenatal testing (NIPT) is to distinguish individual presumptive fetal cells from maternal cells in female pregnancies. We have sought a rapid, robust, versatile, and low-cost next-generation sequencing method to facilitate this process. Toward this goal, single isolated cells underwent whole genome amplification prior to genotyping. Multiple highly polymorphic genomic regions (including HLA-A and HLA-B) with 10-20 very informative single nucleotide polymorphisms (SNPs) within a 200 bp interval were amplified with a modified method based on other publications. To enhance the power of cell identification, approximately 40 Human Identification SNP (Applied Biosystems) test amplicons were also utilized. Using SNP results to compare to sex chromosome data from NGS as a reliable standard, the true positive rate for genotyping was 83.4%, true negative 6.6%, false positive 3.3%, and false negative 6.6%. These results would not be sufficient for clinical diagnosis, but they demonstrate the general validity of the approach and suggest that deeper genotyping of single cells could be completely reliable. A paternal DNA sample is not required using this method. The assay also successfully detected pathogenic variants causing Tay Sachs disease, cystic fibrosis, and hemoglobinopathies in single lymphoblastoid cells, and disease-causing variants in three cell-based NIPT cases. This method could be applicable for any monogenic diagnosis.

Noninvasive prenatal screening for fetal sex chromosome aneuploidies

INTRODUCTION

Sex chromosome aneuploidies (SCAs) are among the most common chromosome abnormalities observed in humans. Manifestations include low fertility, infertility, delayed language development, and dysfunction in motor development. Noninvasive prenatal screening (NIPS) based on cell-free fetal DNA from the peripheral blood of pregnant women is increasingly used for the screening of fetal chromosome abnormalities, including screening for fetal gender and fetal sex chromosome aneuploidy. A systematic review of the literature about NIPS for SCAs is needed.

AREAS COVERED

This review evaluated a vast array of published studies focusing on the clinical significance, detection methods, performance of NIPS for SCAs, and the management of positive SCA results following screening with the aim of facilitating a comprehensive and systematic understanding of NIPS for SCAs.

EXPERT COMMENTARY

Looking forward, NIPS is expected to become the primary screening test for common aneuploidies as well as other chromosome abnormalities, including some micro-deletions and micro-duplications, with the potential to transition from a screening test to a prenatal diagnosis method. Ultimately, the goal is to provide a safe and accurate method for increasing early diagnosis to improve long-term outcomes for the SCA patients and families by well- informed health care providers.

Genetic testing for unexplained perinatal disorders

PURPOSE OF REVIEW

Perinatal disorders include stillbirth, congenital structural anomalies, and critical illnesses in neonates. The cause of these is often unknown despite a thorough clinical workup. Genetic diseases cause a significant portion of perinatal disorders. The purpose of this review is to describe recent advances in genetic testing of perinatal disorders of unknown cause and to provide a potential diagnostic strategy.

RECENT FINDINGS

Exome and genome sequencing (ES and GS) have demonstrated that significant portions of perinatal disorders are caused by genetic disease. However, estimates of the exact proportion have varied widely across fetal and neonatal cohorts and most of the genetic diagnoses found in recent studies have been unique to individual cases. Having a specific genetic diagnosis provides significant clinical utility, including improved prognostication of the outcome, tailored therapy, directed testing for associated syndromic manifestations, referral to appropriate subspecialists, family planning, and redirection of care.

SUMMARY

Perinatal disorders of unknown cause, with nonspecific presentations, are often caused by genetic diseases best diagnosed by ES or GS. Prompt diagnosis facilitates improved clinical care. Improvements in noninvasive sampling, variant interpretation, and population-level research will further enhance the clinical utility of genetic testing.

VIDEO ABSTRACT

http://links.lww.com/MOP/A61.

Prenatal Genetic Diagnosis of a Sex Chromosome Aneuploidy: Parent Experiences

Sex chromosome aneuploidies (SCAs) occur in 1 in every 400 births. SCAs are highly variable and have uncertain prognoses, complicating the delivery of prenatal cell-free DNA (cfDNA) results or diagnosis following amniocentesis or chorionic villus sampling. Using a mixed-methods approach, we explored the experiences of parents receiving a prenatal diagnosis of a fetus with SCA. Responses to open-ended questions were qualitatively analyzed. Of the 323 parents who completed the survey, 122 received a prenatal diagnosis and answered at least one open-ended question. Most parents did not recall being informed that cfDNA screening or amniocentesis could reveal the presence of a SCA prior to testing and described feeling unprepared for a positive result. Variation was found between parents who were delivered a diagnosis by a genetic professional versus other clinical specialties. Many parents expressed that the diagnosis was delivered in a way that emphasized the negative attributes of the SCA and that they were provided limited support materials. Parents who received a prenatal diagnosis of a SCA expressed a desire for more supportive delivery of prenatal diagnosis that focuses on parental education and nuanced discussion of potential phenotypes. Genetic counselors should be aware of the range of parental experiences when receiving a SCA diagnosis from non-genetic providers. Prenatal SCA diagnoses are predicted to increase as prenatal cfDNA screening becomes more widely used. Collaborations for greater provider education and comprehensive materials on SCAs are essential to facilitate the delivery of SCA diagnoses and improve parent understanding and support.

Cell-free DNA analysis of maternal blood in prenatal screening for chromosomal microdeletions and microduplications: a systematic review

BACKGROUND AND AIM OF THE STUDY

Scientific Societies do not recommend the use of cell-free DNA (cfDNA) testing as a first-tier screening for microdeletion and microduplication syndromes (MMs). The aim of this study was to review the current available literature on the performance of cell-free DNA as a screening for MMs.

METHODS

Medline, Embase and the Cochrane Library were searched electronically from 2000 to January 2020 and articles reporting the diagnostic performance of cfDNA screening for MMs in large (>5000 cases) series were included. Between-study heterogeneity and random effect model for screen positive rate (SPR), false positive rate (FPR) and positive predictive value (PPV) were calculated.

RESULTS

We identified 42 papers, seven included, for a total of 474,189 pregnancies and 210 cases of MMs. Diagnostic verification of positive cases was available overall in 486 (71.68 %) of 678 cases. The weighted pooled SPR, FPR and PPV were 0.19% (95% CI = 0.09-0.33), 0.07 (95% CI = 0.02-0.15) and 44.1 (95% CI = 31.49-63.07). In conclusion, the pooled PPV of cfDNA testing in screening for MMs was about 40%, ranging from 29% to 91%, for an overall FPR <0.1%.

CONCLUSIONS

No confirmatory analysis was available in cases that did not undergo invasive testing, which were the vast majority of cases with a negative test, and therefore, the DR and the negative predictive value cannot be determined.

Optimizing Fetal Aneuploidy Screening in an Austere Military Clinical Environment: A Prenatal Cost Comparison

INTRODUCTION

Austere clinical settings, including remote military installations, face unique challenges in screening pregnant women for aneuploidy. The objective of this study was to compare the direct and indirect prenatal costs of traditional 2-part serum-based screening to cell-free DNA (cfDNA) for detection of trisomies 18 and 21 for a military treatment facility with limited in-house perinatal resources.

MATERIALS AND METHODS

We identified Naval Hospital Guantanamo Bay as a surrogate for an austere clinical environment. A prenatal cost of care analysis incorporating direct and indirect expenses was performed to compare the 2 aneuploidy screening strategies for a theoretical cohort of 100 patients for detection of trisomies 18 and 21. The baseline aneuploidy uptake rate was determined using a historical cohort. Test performance characteristics were obtained from the contracting laboratory. Aneuploidy rates and costs were calculated using previously published data.

RESULTS

Assuming a baseline screen uptake rate of 87%, initial screening using the traditional approach would directly cost $8,285.01 versus $44,140.32 with cfDNA. Considering indirect costs such as travel, consultative services, evaluation and follow-up testing of an abnormal screen result, and lost productivity, the cost difference narrows to $14,458.25 over a 5- to 6-year period. Cost equivalence is achieved when cfDNA is priced at $341.17 per test.

CONCLUSION

Cell-free DNA as an initial screening strategy offers enhanced detection rates for trisomies 18 and 21 but remains more costly than traditional screening when incorporating direct and indirect expenses. In a low volume setting with limited resources, the added cost may be justified given the implications of unrecognized aneuploidy.

Not all low fetal fraction cell-free DNA screening failures are at increased risk for aneuploidy

OBJECTIVE

To evaluate cell-free DNA (cfDNA) redraws and pregnancy outcomes following low fetal fraction (FF) cfDNA failures, as it has been suggested that a failed cfDNA screen due to insufficient FF carries increased risk for fetal aneuploidy.

METHODS

Here >200,000 consecutive samples were reviewed and >1,100 patients were identified with a failed cfDNA due to low FF using genome-wide massively parallel sequencing. Redraw results following the initial low FF failure were analyzed, as well as pregnancy outcomes for patients with repeated low FF failure on redraw.

RESULTS

Upon redraw 84.2% of samples yielded a reportable result with no enrichment of aneuploidy observed (p = 0.332). Higher maternal weights and multifetal pregnancy rates were observed in samples with insufficient FF. In patients with repeated low FF failure on redraw, almost all pregnancies resulted in apparently healthy liveborns.

CONCLUSION

Insufficient FF was not an indicator of aneuploidy risk or adverse pregnancy outcomes in this study. Caution should be taken in generalizing aneuploidy risk to all low FF cfDNA failures. Redrawing may be an appropriate next step, as proceeding directly with diagnostic testing for aneuploidy may be unwarranted for most patients.

A fetal reduction from twin to singleton based on sonography and cell-free fetal DNA testing: A sequential approach to old pitfalls

OBJECTIVE

We examined the potential value of combining ultrasound and non-invasive prenatal screening (NIPS) of maternal blood to screen for major aneuploidies as an early approach before selective fetal reduction from twin pregnancy to singleton.

STUDY DESIGN

The sample was composed of pregnant women with di-chorionic di-amniotic twins who chose to undergo fetal reduction to singleton at 12-24 weeks of gestation. These women were asked to provide a blood sample for cell-free fetal DNA (cffDNA) testing prior to fetal reduction.

RESULTS

A total of 24 pregnant women with a twin pregnancy prior to fetal reduction to singleton were enrolled. There were 8 cases with structural anomalies (33.3%) in one twin that dictated fetal reduction. The proportion of patients who underwent selective fetal reduction for fetal abnormalities was larger than in several other studies. The NIPS identified 1 case of Trisomy 13 (4.2%). The other 15 cases (62.5%) had no structural or chromosomal anomalies. The decision to undergo elective reduction of twin pregnancy to singleton was made for social reasons or upon the parents' request. Given the 33% of structural anomalies in the cohort, a cost analysis indicated that this procedure was 6.6-fold less expensive (vs. 4.6-fold with 4% structural anomalies in other publications) than conducting invasive procedures for the entire cohort.

CONCLUSION

The findings suggest that an early anatomical scan and cffDNA can increase the overall safety margin and reduce interventional procedures before elective reduction of twin pregnancy to singleton. However, a larger cohort is needed to confirm these results.

Outcome of publicly funded nationwide first-tier noninvasive prenatal screening

PURPOSE

Noninvasive prenatal screening (NIPS) using cell-free DNA has transformed prenatal care. Belgium was the first country to implement and fully reimburse NIPS as a first-tier screening test offered to all pregnant women. A consortium consisting of all Belgian genetic centers report the outcome of two years genome-wide NIPS implementation.

METHODS

The performance for the common trisomies and for secondary findings was evaluated based on 153,575 genome-wide NIP tests. Furthermore, the evolution of the number of invasive tests and the incidence of Down syndrome live births was registered.

RESULTS

Trisomies 21, 18, and 13 were detected in respectively 0.32%, 0.07%, and 0.06% of cases, with overall positive predictive values (PPVs) of 92.4%, 84.6%, and 43.9%. Rare autosomal trisomies and fetal segmental imbalances were detected in respectively 0.23% and 0.07% of cases with PPVs of 4.1% and 47%. The number of invasive obstetric procedures decreased by 52%. The number of trisomy 21 live births dropped to 0.04%.

CONCLUSION

Expanding the scope of NIPS beyond trisomy 21 fetal screening allows the implementation of personalized genomic medicine for the obstetric population. This genome-wide NIPS approach has been embedded successfully in prenatal genetic care in Belgium and might serve as a framework for other countries offering NIPS.

Next Generation Sequencing Based Non-invasive Prenatal Testing (NIPT): First Report From Saudi Arabia

Background: Non-invasive prenatal testing (NIPT) for aneuploidy in pregnant women screening has been recently established in Saudi Arabia. We aim from this study to report our experience in the implementation of this new technology in clinical practice and to assess factors influencing cell-free fetal (cffDNA) fraction and successful NIPT reporting.

Methods: In total, 200 pregnant women were subjected to the NIPT test using standard methods. Next-generation sequencing (NGS) was used to analyze cffDNA in maternal plasma.

Results: Out of the 200 NIPT cases, the average age of pregnant women was 35 ± 6 years (range: 21–48 years). The average cffDNA fraction of reported cases was 13.72% (range: 3–31%). Out of these 200 cases, 187 (93.5%) were at low risk, while 13 (6.5%) cases revealed high risk for aneuploidy. Among these chromosomal abnormalities, 7 (3.5%) cases of Down’s syndrome, 5 (2.5%) Edwards’ Syndrome, and only 1 case of (0.5%) Patau’s syndrome was observed. Out of the 13 high-risk cases, 2 (15.3%) were found in women below the age of 30.

Conclusion: This is the first study reporting the successful implementation of an in-house NIPT screening service in Saudi Arabia. Our data showed high accuracy and sensitivity to detect high-risk cases indicating the usefulness of such a technique as an alternative to invasive testing and (hopefully) will change the common screening practice for pregnant women in Saudi Arabia.

Clinical Practice Guidelines for Prenatal Aneuploidy Screening and Diagnostic Testing from Korean Society of Maternal-Fetal Medicine: (1) Prenatal Aneuploidy Screening

In 2019, the Korean Society of Maternal-Fetal Medicine developed the first Korean clinical practice guidelines for prenatal aneuploidy screening and diagnostic testing. These guidelines were developed by adapting established clinical practice guidelines in other countries that were searched systematically, and the guidelines aim to assist in decision making of healthcare providers providing prenatal care and to be used as a source for education and communication with pregnant women in Korea. This article delineates clinical practice guidelines specifically for maternal serum screening for fetal aneuploidy and cell-free DNA (cfDNA) screening. A total of 19 key questions (12 for maternal serum and 7 for cfDNA screening) were defined. The main recommendations are: 1) Pregnant women should be informed of common fetal aneuploidy that can be detected, risks for chromosomal abnormality according to the maternal age, detection rate and false positive rate for common fetal aneuploidy with each screening test, limitations, as well as the benefits and risks of invasive diagnostic testing, 2) It is ideal to give counseling about prenatal aneuploidy screening and diagnostic testing at the first prenatal visit, and counseling is recommended to be given early in pregnancy, 3) All pregnant women should be informed about maternal serum screening regardless of their age, 4) cfDNA screening can be used for the screening of trisomy 21, 18, 13 and sex-chromosome aneuploidy. It is not recommended for the screening of microdeletion, 5) The optimal timing of cfDNA screening is 10 weeks of gestation and beyond, and 6) cfDNA screening is not recommended for women with multiple gestations. The guideline was reviewed and approved by the Korean Academy of Medical Sciences.

Non-Invasive Prenatal Testing: Current Perspectives and Future Challenges

Fetal aneuploidies are among the most common causes of miscarriages, perinatal mortality and neurodevelopmental impairment. During the last 70 years, many efforts have been made in order to improve prenatal diagnosis and prenatal screening of these conditions. Recently, the use of cell-free fetal DNA (cff-DNA) testing has been increasingly used in different countries, representing an opportunity for non-invasive prenatal screening of pregnant women. The aim of this narrative review is to describe the state of the art and the main strengths and limitations of this test for prenatal screening of fetal aneuploidies.

Risk stratification for early-onset fetal growth restriction in women with abnormal serum biomarkers: a retrospective cohort study

Abnormal maternal serum biomarkers (AMSB), identified through the aneuploidy screening programme, are frequent incidental findings in pregnancy. They are associated with fetal growth restriction (FGR), but previous studies have not examined whether this association is with early-onset (< 34 weeks) or late-onset (> 34 weeks) FGR; as a result there is no consensus on management. The aims of this study were to determine the prevalence and phenotype of FGR in women with AMSB and test the predictive value of placental sonographic screening to predict early-onset FGR. 1196 pregnant women with AMSB underwent a 21-24 week "placental screen" comprising fetal and placental size, and uterine artery Doppler. Multivariable regression was used to calculate a predictive model for early-onset FGR (birthweight centile < 3rd/< 10th with absent umbilical end-diastolic flow, < 34 weeks). FGR prevalence was high (10.3%), however early-onset FGR was uncommon (2.3%). Placental screening effectively identified early-onset (area under the curve (AUC) 0.93, 95% confidence interval (CI) 0.87-1.00), but not late-onset FGR (AUC 0.70, 95% CI 0.64-0.75). Internal validation demonstrated robust performance for detection/exclusion of early-onset FGR. In this cohort, utilisation of our proposed algorithm with targeted fetal growth and Doppler surveillance, compared with universal comprehensive surveillance would have avoided 1044 scans, potentiating significant cost-saving for maternity services.

Precision of Fetal DNA Fraction Estimation by Quantitative Polymerase Chain Reaction Quantification of a Differently Methylated Target in Noninvasive Prenatal Testing

BACKGROUND

The performance of noninvasive prenatal testing (NIPT) assays is critically determined by the proportion of fetal DNA or fetal fraction (FF). Fetomaternal differential methylation of certain genomic regions has been proposed as a universal marker of fetal origin, and previous reports have suggested the use of methylation-sensitive restriction enzyme (MSRE) assays to estimate FF.

METHODS

We analyzed the performance of FF estimation using an MSRE assay with duplex quantitative polymerase chain reaction (qPCR). Mixtures of genomic DNA from placental cells and from adult women were digested with 2 MSRE and FF estimates obtained, for a total of 221 pairwise treatment/control comparisons.

RESULTS

The coefficient of variance (CV) of the MSRE assays was high, ranging from 24% to 60%. An alternative in silico FF estimation algorithm, SeqFF, displayed slightly lower variability, with a CV of 22%.

CONCLUSION

These results cast doubts on the usefulness of the MSRE-based assay of differentially methylated markers for FF estimation. The lack of a universal method capable of precisely estimating FF remains an incompletely solved issue.

Impact of Emerging Technologies in Prenatal Genetic Counseling

For decades, prenatal testing has been offered to evaluate pregnancies for genetic conditions. In recent years, the number of testing options and range of testing capabilities has dramatically increased. Because of the risks associated with invasive diagnostic testing, research has focused on the detection of genetic conditions through screening technologies such as cell-free DNA. Screening for aneuploidy, copy number variants, and monogenic disorders is clinically available using a sample of maternal blood, but limited data exist on the accuracy of some of these testing options. Additional research is needed to examine the accuracy and utility of screening for increasingly rare conditions. As the breadth of prenatal genetic testing options continues to expand, patients, clinical providers, laboratories, and researchers need to find collaborative means to validate and introduce new testing technologies responsibly. Adequate validation of prenatal tests and effective integration of emerging technologies into prenatal care will become even more important once prenatal treatments for genetic conditions become available.

Applications of noninvasive prenatal testing in vanishing twin syndrome pregnancies after treatment of assisted reproductive technology in a single center

OBJECTIVE

The objective of the study is to assess the clinical application of noninvasive prenatal testing (NIPT) for VTS pregnancies after the treatment of assisted reproductive technology (ART).

METHOD

This was a retrospective study on VTS pregnancies through ART treatment. Participants underwent NIPT at 11 to 13 weeks gestation by sequencing. Resampling was recommended for both positive and testing failure cases. For NIPT positive results, participants were advised to have invasive testing. Clinical outcomes were obtained by telephone interview.

RESULTS

In total of 579 cases, testing failure rates after first sampling and resampling were 7.6% and 1.4%, respectively. Twelve positive results were reported by NIPT. But only one true positive was confirmed, giving a PPV of 8%. A total of 576 cases completed the follow-up (including 533 NIPT negative, 12 positive, and 31 testing failure) and three cases lost follow-up. Among the 536 cases with NIPT negative results, 504 (94.0%) resulted in live-birth and 29 (5.4%) resulted in miscarriage or stillbirths. No false-negative result was reported.

CONCLUSION

NIPT has the potential to be used in prenatal screening for VTS pregnancies. For the pregnant women who obtained positive and testing failure results, resampling after 15 weeks of gestation is recommended.

Impact of mosaicism ratio on positive predictive value of cfDNA screening

OBJECTIVE

To examine the relationship between the fraction of cell-free DNA (cfDNA) affected by aneuploidy compared to the overall fetal fraction of a prenatal screening specimen and its effect on positive predictive value (PPV).

METHOD

CfDNA specimens positive for trisomy 13, 18, and 21 with diagnostic outcomes were analysed over a 22-month period in one clinical laboratory. For each positive specimen, a "mosaicism ratio" (MR) was calculated by dividing the fraction of cfDNA affected by aneuploidy by the overall fetal fraction of the specimen. PPVs were calculated and analyzed based on various MR ranges.

RESULTS

Trisomy 13 was the aneuploidy most commonly seen in mosaic form, followed by trisomy 18 and trisomy 21. Significant differences in positive predictive values were noted for all three trisomies between samples with an MR in the "mosaic" versus "non-mosaic" range, as well as between results classified as "low-mosaic" versus "high-mosaic."

CONCLUSION

PPVs may be influenced, in part, by the mosaicism ratio associated with a particular result. The data generated from this study may be useful in providing more personalized risk assessments for patients with positive cfDNA screening results.

A cross-sectional survey of pregnant women's knowledge of chromosomal aneuploidy and microdeletion and microduplication syndromes

OBJECTIVE

The purpose of this survey is to evaluate the knowledge of Chinese pregnant women about fetal chromosomal aneuploidy and microdeletion and microduplication syndromes, and Non-invasive prenatal testing (NIPT).

STUDY DESIGN

Written questionnaires were distributed to pregnant women who visited the fetal medicine clinic of the third affiliated hospital of Guangzhou medical university. A total of 330 questionnaires were given. Twenty-two questionnaires with incomplete information were excluded from further analysis. The remaining 308 cases were incorporated into the final analysis. Data were analyzed using IBM SPSS Statistics 26. Comparisons between categorical variables were tested by the use of crosstabs and χ 2 test.

RESULTS

Among pregnant women, the recognition of Down syndrome was the highest (93.5 %), followed by maternal serum screening (74.0 %) and NIPT (69.2 %) for chromosomal aneuploidy. The awareness rates of chromosomal microdeletions and microduplications (18.2 %) and monogenic disorders (13.3 %) were the lowest. There were no significant differences in age, education, and conception way between pregnant women (P > 0.05). When asked the opinion on increasing the testing range of NIPT, more than 50 % of pregnant women chose to follow the provider's advice.

CONCLUSION

More than half of pregnant women lacked knowledge of screening methods for fetal chromosomal abnormalities. Less than 20 % of pregnant women knew microdeletion microduplication syndromes. To enhance the understanding of chromosomal abnormalities can ensure that women can actively choose tests rather than passively agreeing to their provider's recommendations so as to avoid missing the optimal prenatal screening time.

Neonatal complications of Down syndrome and factors necessitating intensive care

Limited knowledge exists about how frequently newborns with Down syndrome receive a prenatal diagnosis, require intensive care, and what surgical and medical factors are contributory. A retrospective cohort study was performed for patients with a diagnosis of Down syndrome born in 2013 and 2014 who sought care at Cincinnati Children's Hospital Medical Center during the first year of life. Data were extracted from the electronic medical record through the first year of life including need for intensive care as a newborn, prenatal diagnosis, and medical and surgical complications. Of the 129 patients in the study, 65% required intensive care as newborns. The presence of a structural abnormality that required surgical correction in the neonatal period and certain types of congenital heart disease not requiring surgical intervention in the neonatal period were positively associated with the need for intensive care. A minority of infants, 8%, had a confirmed prenatal diagnosis. A majority of newborns with Down syndrome required intensive care following birth while a minority had any concern for the diagnosis prenatally. Improving prenatal diagnostic rates would allow for better prenatal counseling and delivery planning, while targeting therapeutic interventions for this population is needed to improve outcomes.

Clinical Review of Noninvasive Prenatal Testing: Experience from 551 Pregnancies with Noninvasive Prenatal Testing-Positive Results in a Tertiary Referral Center

A total of 551 pregnancies with positive results for noninvasive prenatal testing (NIPT) using traditional karyotyping and chromosomal microarray analysis were analyzed. Confirmatory results, positive predictive values, etiology exploration of false-positive results, and pregnancy outcomes were recorded. The study demonstrated that NIPT performed better in predicting trisomy 21 and trisomy 18 for pregnancies with advanced maternal age than for pregnancies with young maternal age; as for trisomy 13 and sex chromosomal aneuploidy (SCA) prediction, there was no significant difference between the two groups. The positive predictive values for trisomy 21, trisomy 18, trisomy 13, and SCA showed no significant upward trend when compared based on specific age categories (an interval of 5 years), which suggested that NIPT-positive result deserves equal attention from both providers and patients regardless of maternal age. In addition, the termination rates of 45,X, 47,XXY, 47,XXX, and 47,XYY were 100% (2/2), 92.9% (26/28), 33.3% (5/15), and 9.5% (2/21), respectively, which demonstrated that the decision-making regarding pregnancies varied greatly according to the types of SCAs, and further reinforce the importance of confirmatory prenatal diagnosis. The current study also supported the viewpoint that confined placental mosaicism and maternal mosaicism were the important etiology of false-positive results.

Interpretation of noninvasive prenatal testing results following in vitro fertilization and preimplantation genetic testing for aneuploidy

BACKGROUND

The positive predictive value of noninvasive prenatal testing is approximately 69% in the general population. However, positive predictive value is dependent on the prevalence of the disease in the population being tested. Patients who undergo in vitro fertilization with preimplantation genetic testing for aneuploidy and transfer a euploid embryo are presumably a lower risk population than the general population.

OBJECTIVE

In this study, we explored the positive predictive value of noninvasive prenatal testing in women undergoing in vitro fertilization with preimplantation genetic testing for aneuploidy and subsequent transfer of a euploid embryo.

STUDY DESIGN

This study was a retrospective cohort study. All patients who underwent in vitro fertilization with preimplantation genetic testing for aneuploidy followed by transfer of a single euploid embryo between 2014 and 2019 at a university-affiliated fertility center were contacted. Noninvasive prenatal testing results were reviewed and those with positive noninvasive prenatal testing were identified. Results of any subsequent prenatal or postnatal diagnostic testing were used to classify each positive noninvasive prenatal testing as a true positive or a false positive. The prevalence and positive predictive value of positive noninvasive prenatal testing was calculated.

RESULTS

A total of 1139 patients that underwent noninvasive prenatal testing after transfer of a euploid embryo were identified, 8 of which had positive noninvasive prenatal testing screens. Although 6 of these patients had subsequent definitive prenatal diagnostic testing that revealed a euploid karyotype concordant with their preimplantation genetic testing for aneuploidy results, 1 patient opted out of diagnostic testing and later delivered a normal baby. Of note, 1 patient who had noninvasive prenatal testing positive for Turner syndrome underwent amniocentesis, which confirmed Turner mosaicism (45,X karyotype in 80% of cells). Therefore, the positive predictive value of noninvasive prenatal testing in this patient cohort was 12.5%.

CONCLUSION

Clinicians and patients should recognize that patients undergoing transfer of a euploid embryo are at a relatively lower risk for fetal aneuploidy than the general population, and the positive predictive value of noninvasive prenatal testing is lower in this setting.

Should vanishing twin pregnancies be systematically excluded from cell-free fetal DNA testing?

OBJECTIVE

To demonstrate the feasibility of cell-free DNA (cfDNA) testing in vanishing twin (VT) pregnancies in routine clinical practice.

METHODS

Our study included 24 874 singleton and 206 VT consecutive pregnancies. Cell-free DNA was analyzed by massively parallel sequencing. Both aneuploidy analysis (chromosomes 13,18, 21, X, and Y) and fetal fraction estimation were performed according to an Illumina algorithm. Contaminant DNA contribution from the demised co-twin was studied in detail.

RESULTS

VT pregnancies exhibited a higher prevalence of screen-positive cases (5.8% vs 2.5%), sex discrepancies (10.2% vs 0.05%), and false positive rates (FPR) (2.6% vs 0.3%) than singleton pregnancies. However, their incidence was significantly lower in tests performed after the 14th week (screen-positive cases: 3.1%; sex discrepancies: 7.8%; and FPR: 0.8%). Among the 12 cases in which cfDNA was performed at two time points, fading of contaminating cfDNA was observed in four cases with a sex discrepancy and in one false positive for trisomy 18, resulting in a final correct result.

CONCLUSIONS

Our data suggest VT pregnancies could be included in cfDNA testing as long as it is applied after the 14th week of pregnancy. However, future studies to validate our findings are needed before including VT cases in routine clinical practice. Once established, unnecessary invasive procedures could be avoided, mitigating negative emotional impact on future mothers.