Disparities in integrating non-invasive prenatal testing into antenatal healthcare in Australia: a survey of healthcare professionals.

BACKGROUND: Non-invasive prenatal testing (NIPT) has been clinically available in Australia on a user-pays basis since 2012. There are numerous providers, with available tests ranging from targeted NIPT (only trisomies 21, 18, and 13 +/- sex chromosome aneuploidy) to genome-wide NIPT. While NIPT is being implemented in the public health care systems of other countries, in Australia, the implementation of NIPT has proceeded without public funding. The aim of this study was to investigate how NIPT has been integrated into antenatal care across Australia and reveal the successes and challenges in its implementation in this context. METHODS: An anonymous online survey was conducted from September to October 2022. Invitations to participate were sent to healthcare professionals (HCPs) involved in the provision of NIPT in Australia through professional society mailing lists and networks. Participants were asked questions on their knowledge of NIPT, delivery of NIPT, and post-test management of results. RESULTS: A total of 475 HCPs responded, comprising 232 (48.8%) obstetricians, 167 (35.2%) general practitioners, 32 (6.7%) midwives, and 44 (9.3%) genetic specialists. NIPT was most commonly offered as a first-tier test, with most HCPs (n = 279; 60.3%) offering it to patients as a choice between NIPT and combined first-trimester screening. Fifty-three percent (n = 245) of respondents always offered patients a choice between NIPT for the common autosomal trisomies and expanded (including genome-wide) NIPT. This choice was understood as supporting patient autonomy and informed consent. Cost was seen as a major barrier to access to NIPT, for both targeted and expanded tests. Equitable access, increasing time demands on HCPs, and staying up to date with advances were frequently reported as major challenges in delivering NIPT. CONCLUSIONS: Our findings demonstrate substantial variation in the clinical implementation of NIPT in Australia, including in the offers of expanded screening options. After a decade of clinical use, Australian clinicians still report ongoing challenges in the clinical and equitable provision of NIPT.

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.

Use of cell-free non-invasive prenatal testing in pregnancies affected by placental mosaicism.

OBJECTIVE: To evaluate cell-free non-invasive prenatal testing (cfNIPT) in pregnancies affected by mosaicism. METHOD: We assessed paired cfNIPT and chorionic villus sample (CVS) results from the same pregnancies in a case series of mosaicism detected in Central and North Denmark Regions from April 2014 to September 2018. Indications for the clinically obtained CVS, pregnancy markers and outcome were retrieved from The Danish Fetal Medicine Database. RESULTS: Mosaicisms in CVS involved common aneuploidy, n = 14; sex chromosomal aneuploidies, n = 14; rare autosomal trisomies (RATs), n = 16 and copy number variants (CNVs) >5Mb, n = 9. Overall, 24/53 (45.3%; CI 95%: 31.8%-59.4%) of cases with mosaicism were detected by cfNIPT; highest for RATs (56%) and lowest for CNVs (22%). CfNIPT more commonly detected high-level than low-level mosaic cases (p = 0.000). CfNIPT detected 7/16 (43.8%; CI 95%: 21%-69%) clinically significant mosaic cases, either true fetal mosaicism or confined placental mosaicisms with adverse pregnancy outcome. There was a trend toward a higher risk for adverse outcome in pregnancies where mosaicism was detected by cfNIPT compared to pregnancies where mosaicism was not detected by cfNIPT (p = 0.31). CONCLUSION: CfNIPT has a low detection rate of mosaicism, including pregnancies with clinically significant mosaicism. However, abnormal cfNIPT results may be a predictor of adverse pregnancy outcomes.

Patients' choices and opinions on chorionic villous sampling and non-invasive alternatives for prenatal testing following preimplantation genetic testing for hereditary disorders: A cross-sectional questionnaire study.

OBJECTIVE: The aim of this study was to investigate choices of and reasoning behind chorionic villous sampling and opinions on non-invasive prenatal testing among women and men achieving pregnancy following preimplantation genetic testing (PGT) for hereditary disorders. METHODS: A questionnaire was electronically submitted to patients who had achieved a clinical pregnancy following PGT at the Center for Preimplantation Genetic Testing, Aalborg University Hospital, Denmark, between 2017 and 2020. RESULTS: Chorionic villous sampling was declined by approximately half of the patients. The primary reason for declining was the perceived risk of miscarriage due to the procedure. Nine out of 10 patients responded that they would have opted for a non-invasive prenatal test if it had been offered. Some patients were not aware that the nuchal translucency scan offered to all pregnant women in the early second trimester only rarely provides information on the hereditary disorder for which PGT was performed. CONCLUSION: Improved counseling on the array of prenatal tests and screenings available might be required to assist patients in making better informed decisions regarding prenatal testing. Non-invasive prenatal testing is welcomed by the patients and will likely increase the number of patients opting for confirmatory prenatal testing following PGT for hereditary disorders.

Clinical utility of expanded NIPT for chromosomal abnormalities and etiology analysis of cytogenetic discrepancies cases.

PURPOSE: This study is to assess the performance of expanded noninvasive prenatal testing (NIPT) in detecting chromosome aneuploidies and chromosome copy number variants (CNVs), and elucidate the discordant cases between NIPT and fetal karyotype. METHODS: A total of 2139 single pregnancies have been recruited and sequenced with expanded NIPT. Karyotype analysis and CNV sequencing (CNV-seq) of amniotic fluid were performed in 22 of 23 high-risk, three low-risk NIPT pregnant women with abnormal ultrasound findings in the follow-up, and three non-reportable NIPT pregnant women. The genetic investigation of discordant results between NIPT and amniocytes in three cases was proceeded. Placental samples, fetal samples from the limb, hip, umbilical cord, and maternal peripheral blood leukocytes were collected for CNV-Seq. RESULTS: Expanded NIPT revealed a total of 23 positive pregnancies and yielded the overall positive predictive value (PPV) 65.2%. For T21, T18, and XXY, all the PPV was 100% respectively. For CNVs > 10 Mb and 5-10 Mb, the PPV was 42.8% and 16.7%, respectively. The genetic investigation of placental and fetal samples indicated different levels of placental and fetal mosaicism contributing to two of three verified discordant results. CONCLUSIONS: The results showed that screening for CNVs with expanded NIPT is promising although the accuracy rate remains insufficient. The different occurring time of mitotic non-disjunction of different chromosome in early development of embryo results in varying levels of chromosomal mosaicism in different placental and fetal tissues. The result highlights the significance of comprehensive cytogenetic validation of placental and fetal specimens with an inconsistent NIPT results.

Influence of fibroids on cell-free DNA screening accuracy.

OBJECTIVE: Cell-free DNA (cfDNA) screening assesses both maternal and placental cfDNA. Fibroids are common and release cfDNA into maternal serum. Genetic abnormality is seen in 50% of fibroids. We aimed to assess the impact of fibroids on the accuracy of genome-wide cfDNA screening. METHODS: This was a prospective cohort study of singleton pregnancies examined at one of two centers in Melbourne and Sydney, Australia, between 1 November 2019 and 31 December 2020. All cases underwent pretest ultrasound examination to confirm an ongoing pregnancy of at least 10 weeks' gestation, and, at this stage, the number and volume of any uterine fibroid were documented. Genome-wide cfDNA screening was performed to detect all copy-number variants (CNV) > 7 megabases. The incidence of a false-positive result was compared between cases with and those without fibroids. RESULTS: Over the 14-month study period, 13 184 patients underwent cfDNA screening, of whom 1017 (7.7%) had fibroids. Fibroids were not identified in any of the 17 participants who had a false-positive result for chromosomes 13, 18, 21, X or Y. Ninety-five (0.7%) cases were screen-positive for subchromosomal aberration (SA), rare autosomal trisomy (RAT) or multiple abnormalities (MA), with 10 of these cases having a fetal genetic abnormality. The incidence of a false-positive RAT, MA or SA result was significantly higher in participants with fibroids (20/1017 (2.0%)) than in those without fibroids (64/12 167 (0.5%)). Women with fibroids were approximately six times as likely to have a false-positive result for SA, and this was associated positively with both fibroid number and volume. CONCLUSIONS: Most women with fibroids do not have an abnormal result on genome-wide cfDNA screening. However, CNVs due to fibroids are associated with false-positive SA findings, although fibroids do not appear to influence cfDNA screening accuracy for the common autosomal trisomies or sex-chromosomal abnormalities. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Knowledge, attitudes, and practices of healthcare professionals working in prenatal diagnosis toward expanded non-invasive prenatal testing in China.

OBJECTIVES: To investigate the knowledge, attitudes, and practices of healthcare professionals (HCPs) working in prenatal diagnosis toward expanded non-invasive prenatal testing (NIPT) in China. METHODS: We conducted a national online survey among HCPs working in prenatal diagnosis, including specialists in prenatal diagnosis and foetal medicine, obstetricians and gynaecologists, nurses in obstetrics and gynaecology, obstetric ultrasound doctors, and technicians in prenatal diagnosis laboratories. A total of 1882 questionnaires were collected, among which 1822 questionnaires met the research criteria and were included in the analysis. RESULTS: More than 99% of all participants opted for NIPT for trisomies 21, 18, and 13. The rates of support for expanded NIPT for sex chromosome aneuploidies, rare autosomal trisomies, microdeletions and microduplications, and single-gene disorders were 93.9%, 88.6%, 89.4%, and 86.8%, respectively. Specialists in prenatal diagnosis and foetal medicine had greater knowledge but were less likely to support expanded NIPT compared to other participants. Knowledge increased with educational level, whereas support for expanded NIPT decreased with educational level. CONCLUSIONS: More than 80% of HCPs working in prenatal diagnosis in China expressed support for expanding NIPT to conditions other than common trisomies. The degree of knowledge was negatively associated with the rate of support.

Non-invasive prenatal test uptake in socioeconomically disadvantaged neighborhoods.

OBJECTIVE: Non-Invasive Prenatal Testing (NIPT) is increasingly being implemented worldwide. In public health programs, equitable access to healthcare is a fundamental principle which also applies to fetal aneuploidy screening. However, the out-of-pocket costs of NIPT may lead to sociodemographic disparities in uptake of screening. This study assessed whether there is a difference in the uptake of NIPT in socioeconomically disadvantaged neighborhoods compared to all other neighborhoods in the Netherlands, where NIPT is implemented in a national screening program (TRIDENT-2 study). METHOD: NIPT uptake, postal code and age of 156,562 pregnant women who received pre-test counselling for prenatal screening in 2018 were retrieved from the national prenatal screening database. Postal codes were used as a proxy to categorize neighborhoods as being either socioeconomically disadvantaged or other. The out-of-pocket costs for NIPT were €175. RESULTS: NIPT uptake in socioeconomically disadvantaged neighborhoods was 20.3% whereas uptake in all other neighborhoods was 47.6% (p < 0.001). The difference in NIPT uptake between socioeconomic disadvantaged neighborhoods and other areas was smaller for the youngest maternal age-group (≤25 years) compared to other age-groups. CONCLUSION: The variation in uptake suggest underlying disparities in NIPT uptake, which undermines the goals of a national fetal aneuploidy screening program of providing reproductive autonomy and equitable access. This has ethical and policy implications for ensuring fair and responsible implementation of fetal aneuploidy screening.

Genetic landscape of 125 pharmacogenes in Chinese from the Chinese Millionome Database.

Inter-individual differences of drug responses could be attributed to genetic variants of pharmacogenes such as cytochrome P450 (CYP), phase 2 enzymes, and transporters. In contrast to extensive studies on the genetic polymorphisms of CYP gene, genetic mutation spectrum of other pharmacogenes was under-representative in the pharmacogenetics investigations. Here we studied the genetic variations of 125 pharmacogenes including drug transporters, non-CYP phase 1 enzymes, phase 2 enzymes, nuclear receptors and others in Chinese from the Chinese Millionome Database (CMDB), of which 38,188 variants were identified. Computational analyses of the 2554 exonic variants found 617 deleterious missense variants, 91.1% of which were rare, and of the 54 loss-of-function (splice acceptor, splice donor, start lost, and stop gained) variants, 53 (98.1%) were rare. These results suggested an enrichment of rare variants in functional ones for pharmacogenes. Certain common functional variants including NUDT15 13:48611934 G/A (rs186364861), UGT1A1 2:234676872 C/T (rs34946978), and ALDH2 12:112241766 G/A (rs671) were population-specific for CMDB Chinese because they were absent (with a zero of variant allele frequency) or very rare in other gnomAD populations. These findings might be useful for the further pharmacogenomics research and clinical application in Chinese.

Cell-free DNA screening for fetal aneuploidy using the rolling circle method: A step towards non invasive prenatal testing simplification.

OBJECTIVE: To assess the efficacy of cell-free (cf)DNA screening for aneuploidy using the automated system based on rolling circle replication. METHODS: A prospective study among women referred for invasive prenatal diagnosis between July 2018 and December 2019. The plasma fraction was extracted within 5 days from blood collection, stored at -20°C and cfDNA measured between January and December 2019. RESULTS: A total of 805 women were recruited; 778 with singleton pregnancies and 27 twins. There were 48 Down syndrome, 25 Edwards syndrome and 3 Patau syndrome cases. Overall, the no-call rate was 2.6% (95% confidence interval 1.6%-3.9%) which reduced from 4.7% to 1.1% after relocation of the system (p < 0.002) to ensure a constant ambient temperature below 25°C. In singletons the Down syndrome detection rate (DR) was 100% (93%-100%) and false-positive rate (FPR) 0.14% (0.00%-0.79%). The Edwards syndrome DR was 96% (80%-100%) and FPR 0.78% (0.29%-1.7%). One false-positive had a confined placental trisomy 18 and the remaining five a z-score requiring sample repetition; all the false-positives occurred before system relocation (p < 0.005). Patau syndrome DR and FPR were 67% (9.4%-99%) and 0.26% (0.03%-0.95%). CONCLUSION: The cfDNA rolling circle method yields similar results to other methods provided that room temperature is adequately controlled.

Predicting neonatal outcomes in infants with giant omphalocele using prenatal magnetic resonance imaging calculated observed-to-expected fetal lung volumes.

OBJECTIVE: To examine the association between prenatal magnetic resonance imaging (MRI) based observed/expected total lung volume (O/E TLV) and outcome in neonates with giant omphalocele (GO). METHODS: Between 06/2004 and 12/2019, 67 cases with isolated GO underwent prenatal and postnatal care at our institution. MRI-based O/E TLVs were calculated based on normative data from Meyers and from Rypens and correlated with postnatal survival and morbidities. O/E TLV scores were grouped based on severity into <25% (severe), between 25% and 50% (moderate), and >50% (mild) for risk stratification. RESULTS: O/E TLV was calculated for all patients according to Meyers nomograms and for 49 patients according to Rypens nomograms. Survival for GO neonates with severe, moderate, and mild pulmonary hypoplasia based on Meyers O/E TLV categories was 60%, 92%, and 96%, respectively (p = 0.04). There was a significant inverse association between Meyers O/E TLV and risk of neonatal morbidities (p < 0.05). A similar trend was observed with Rypens O/E TLV, but associations were less often significant likely related to the smaller sample size. CONCLUSION: Neonatal outcomes are related to fetal lung size in isolated GO. Assessment of Meyers O/E TLV allows identification of GO fetuses at greatest risk for complications secondary to pulmonary hypoplasia.

Racial and ethnic differences in uptake of cell-free fetal DNA aneuploidy screening in an urban safety net hospital.

OBJECTIVE: To identify racial disparities in cell-free fetal DNA (cffDNA) first-line aneuploidy screening use among advanced maternal age women at a safety net hospital. STUDY DESIGN: This retrospective cohort study of women 35 and older who delivered at Boston Medical Center from 2012 to 2015 compared to women who used cffDNA for first-line aneuploidy screening to those who did not. Maternal conventional demographics and social determinants of health were collected. We investigated the relationship between race and odds of cffDNA use, adjusting for covariates by stepwise logistic regression. RESULTS: We identified 1223 women. Seventy-two percent were publicly insured. Upon adjusting for parity, prenatal care site, year of delivery, and insurance status, odds of cffNDA use remained lower for Black and Hispanic women (adjusted odds ratio [aOR] 0.47, 95% confidence interval [CI] 0.30, 0.71 and aOR 0.34 [0.21, 0.55]) compared to White women. Language proved to be an effect modifier among Hispanic women that attenuated but did not resolve the disparity in use among Hispanic compared to White women. Racial differences in cffDNA use persisted across the study period. CONCLUSION: Disparity in cffDNA screening uptake exists by race in this diverse urban population. The gap in utilization between Hispanic and White women may be related to primary preferred language.

Investigation on combined copy number variation sequencing and cytogenetic karyotyping for prenatal diagnosis.

BACKGROUND: We aimed to evaluate the clinical value of copy number variation-sequencing (CNV-Seq) in combination with cytogenetic karyotyping in prenatal diagnosis. METHODS: CNV-Seq and cytogenetic karyotyping were performed in parallel for 9452 prenatal samples for comparison of the diagnostic performance of the two methods, and to evaluate the screening performance of maternal age, maternal serum screening, fetal ultrasound scanning and noninvasive prenatal testing (NIPT) for fetal pathogenic copy number variation (CNV). RESULTS: Among the 9452 prenatal samples, traditional karyotyping detected 704 cases (7.5%) of abnormal cytogenetic karyotypes, 171 (1.8%) chromosome polymorphism, 20 (0.2%) subtle structural variations, 74 (0.7%) mutual translocation (possibly balanced), 52 (0.6%) without karyotyping results, and 8431 (89.2%) normal cytogenetic karyotypes. Among the 8705 cases with normal karyotype, polymorphism, mutual translocation, or marker chromosome, CNV-Seq detected 63 cases (0.7%) of pathogenic chromosome microdeletion/duplication. Retrospectively, noninvasive prenatal testing (NIPT) had high sensitivity and specificity for the screening of fetal pathogenic CNV, and NIPT combining with maternal age, maternal serum screening or fetal ultrasound scanning, which improved the screening performance. CONCLUSION: The combined application of cytogenetic karyotyping and CNV-Seq significantly improved the detection rate of fetal pathogenic chromosome microdeletion/duplication. NIPT was recommended for the screening of pathogenic chromosome microdeletion/duplication, and NIPT combining with other screening methods further improved the screening performance for pathogenic fetal CNV.

The potential of expanded noninvasive prenatal screening for detection of microdeletion and microduplication syndromes.

OBJECTIVES: To evaluate the clinical potential of a higher resolution noninvasive prenatal screening (NIPS-Plus) test for detection of microdeletion/microduplication syndromes (MMS) in addition to common aneuploidies. METHODS: In a multicenter prospective study, 37,002 pregnant women with unremarkable first-trimester ultrasound scans had a NIPS-Plus test. Ultrasound screen positive women were not included in this study. RESULTS: Of 36,970 ultrasound negative women there were 291 NIPS-Plus screen positive results indicating 237 aneuploidies and 54 MMS. Following amniocentesis, 171 (72%) were confirmed as genuine, comprising 3 T13s, 10 T18s, 61 T21s, 70 SCAs and 27 MMS. The PPV for MMS with unremarkable ultrasound findings was 50%. Routine clinical examination of children born from NIPS-Plus negative pregnancies revealed no obvious signs of chromosome disease syndromes at one year of age. CONCLUSIONS: NIPS-Plus has the potential for clinical utility not only for routine aneuploid screening but also for MMS that do not show overt signs during early pregnancy ultrasound screening. We suggest that ultrasound with NIPS-Plus in combination with appropriate counselling could be considered as a comprehensive first-tier prenatal screening approach for all pregnant women.

Prenatal prediction of fetal Rh C, c and E status by amplification of maternal cfDNA and deep sequencing.

BACKGROUND: The Rh blood group system has considerable clinical importance. The C, c, and E antigens are targets of alloantibodies. Anti-C, anti-c or anti-E alloreactive antibodies produced in pregnant women can cause anemia of a fetus carrying the corresponding antigens. AIMS: Based on NGS technology, we have developed a noninvasive diagnostic assay to predict the fetal blood group of C, c or E antigens by sequencing cell-free DNA (cfDNA) during pregnancy. MATERIALS AND METHODS: The SNVs underlying either the C, c or E antigens were PCR amplified and sequenced using NGS on a MiSeq instrument. The DNA sequences encoding the C, c or E antigen were counted, as were the number of total sequences. Based on the percentage of fetally derived target SNVs inherited from the father, the fetal blood group could be predicted. RESULTS: The results of 55 consecutive RHCE prenatal analyses with postnatal serological blood group determination of 30 newborns showed no discordant results. A threshold discerning positive from negative samples was set at 0.05% specific reads. DISCUSSION: Noninvasive, prenatal prediction of fetal blood groups by sequencing cfDNA for the detection of low-level RHCE*C, RHCE*c and RHCE*E sequences was established as an accurate and robust assay applicable for use in clinical settings.

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.

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.

The diagnostic efficacy of exome data analysis using fixed neurodevelopmental gene lists: Implications for prenatal setting.

OBJECTIVE: Laboratories performing prenatal exome sequencing (ES) frequently limit analysis to predetermined gene lists. We used a diagnostic postnatal ES cohort to assess how many of the genes diagnosed are not included in a number of select fixed lists used for prenatal diagnosis. METHODS: Of 601 postnatal ES tests, pathogenic variants related to neurodevelopmental disorders were detected in 138 probands. We evaluated if causative genes were present in the following: (1) Developmental Disorders Genotype-Phenotype database list, (2) a commercial laboratory list for prenatal ES, (3) the PanelApp fetal anomalies panel, and (4) a published list used for prenatal diagnosis by ES (Prenatal Assessment of Genomes and Exomes study). RESULTS: The percentages of cases where the diagnosed gene was not included in the selected four lists were; 11.6%, 17.24%, 23.2%, and 10.9%, respectively. In 13/138 (9.4%) cases, the causative gene was not included in any of the lists; in 4/13 (∼30%) cases noninclusion was explained by a relatively recent discovery of gene-phenotype association. CONCLUSIONS: A significant number of genes related to neurocognitive phenotypes are not included in some of the lists used for prenatal ES data interpretation. These are not only genes related to recently discovered disorders, but also genes with well-established gene-phenotype.

Fetal esophageal imaging: Early pregnancy as a window of opportunity.

OBJECTIVE: To describe the sonographic appearance of the fetal esophagus during early pregnancy and evaluate the feasibility of imaging the entire esophageal length. In addition, we present a case of disrupted esophageal continuity, subsequently diagnosed with esophageal atresia (EA). METHODS: A prospective observational study of 145 patients. During the early second trimester anomaly scan performed at 12-17 weeks' gestation the entire esophagus was captured in a single sonographic image at the midsagittal plane (one shot technique). Postnatal follow-up of esophageal patency included review of medical records and telephone interviews. RESULTS: Complete visualization of the esophagus (neck to diaphragm) was possible in 144 cases. In 88% of cases the esophagus was demonstrated by transvaginal approach. The time required to obtain the desired view of the esophagus, once the fetus was in an optimal position, was on average 13 s (range: 5-30 s). In one case at 15 weeks' gestation, the cervical segment of the esophagus was demonstrated while the lower thoracic segment was not identified. Subsequently EA was diagnosed. CONCLUSIONS: It is feasible to demonstrate the entire esophagus during early second trimester anomaly scan. An early second trimester anomaly scan may serve as a window of opportunity for EA screening.