Genomic microarray in fetuses with increased nuchal translucency and normal karyotype: a systematic review and meta-analysis

First-Trimester Ultrasound Screening in Routine Obstetric Practice

Technologic advances and ultrasonographer-physician experience in fetal imaging have led to significant improvements in our ability to distinguish between normal and abnormal fetal structural development in the latter part of the first trimester. As a critical component of pregnancy care, assessment of fetal anatomy at the end of the first trimester with a standardized imaging protocol should be offered to all pregnant patients regardless of aneuploidy screening results because it has been demonstrated to identify approximately half of fetal structural malformations. Early identification of abnormalities allows focused genetic counseling, timely diagnostic testing, and subspecialist consultation. In addition, a normal ultrasound examination result offers some degree of reassurance to most patients. Use of cell-free DNA alone for aneuploidy screening while foregoing an accompanying early anatomic evaluation of the fetus will result in many anomalies that are typically detected in the first trimester not being identified until later in pregnancy, thus potentially diminishing the quality of obstetric care for pregnant individuals and possibly limiting their reproductive options, including pregnancy termination.

Prenatal cardiac findings and 22q11.2 deletion syndrome: Fetal detection and evaluation

Clinical features of 22q11.2 microdeletion syndrome (22q11.2DS) are highly variable between affected individuals and frequently include a subset of conotruncal and aortic arch anomalies. Many are diagnosed with 22q11.2DS when they present as a fetus, newborn or infant with characteristic cardiac findings and subsequently undergo genetic testing. The presence of an aortic arch anomaly with characteristic intracardiac anomalies increases the likelihood that the patient has 22q11.2 DS, but those with an aortic arch anomaly and normal intracardiac anatomy are also at risk. It is particularly important to identify the fetus at risk for 22q11.2DS in order to prepare the expectant parents and plan postnatal care for optimal outcomes. Fetal anatomy scans now readily identify aortic arch anomalies (aberrant right subclavian artery, right sided aortic arch or double aortic arch) in the three-vessel tracheal view. Given the association of 22q11.2DS with aortic arch anomalies with and without intracardiac defects, this review highlights the importance of recognizing the fetus at risk for 22q11.2 deletion syndrome with an aortic arch anomaly and details current methods for genetic testing. To assist in the prenatal diagnosis of 22q11.2DS, this review summarizes the seminal features of 22q11.2DS, its prenatal presentation and current methods for genetic testing.

Prenatal Diagnosis by Trio Clinical Exome Sequencing: Single Center Experience

Fetal anomalies, characterized by structural or functional abnormalities occurring during intrauterine life, pose a significant medical challenge, with a notable prevalence, affecting approximately 2-3% of live births and 20% of spontaneous miscarriages. This study aims to identify the genetic cause of ultrasound anomalies through clinical exome sequencing (CES) analysis. The focus is on utilizing CES analysis in a trio setting, involving the fetuses and both parents. To achieve this objective, prenatal trio clinical exome sequencing was conducted in 51 fetuseses exhibiting ultrasound anomalies with previously negative results from chromosomal microarray (CMA) analysis. The study revealed pathogenic variants in 24% of the analyzed cases (12 out of 51). It is worth noting that the findings include de novo variants in 50% of cases and the transmission of causative variants from asymptomatic parents in 50% of cases. Trio clinical exome sequencing stands out as a crucial tool in advancing prenatal diagnostics, surpassing the effectiveness of relying solely on chromosomal microarray analysis. This underscores its potential to become a routine diagnostic standard in prenatal care, particularly for cases involving ultrasound anomalies.

Decoding 22q11.2: prenatal profiling and first-trimester risk assessment in Danish nationwide cohort

OBJECTIVES

To examine the distribution of nuchal translucency thickness (NT), free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) in pregnancies with a fetal 22q11.2 aberration. Furthermore, the performance of combined first-trimester screening (cFTS) and a new risk algorithm targeting 22q11.2 deletions in detecting affected pregnancies was evaluated. Finally, prenatal malformations and pregnancy outcome were assessed.

METHODS

This was a nationwide registry-based cohort study of all pregnancies that underwent prenatal screening with a due date between January 2008 and December 2018 in Denmark. All cases with a fetal 22q11.2 deletion or duplication (hg19 chr22:18.9mio-25.0mio) diagnosed pre- or postnatally or following pregnancy loss or termination of pregnancy were retrieved from the Danish Cytogenetic Central Register and linked with pregnancy data from the Danish Fetal Medicine Database. Fetal and maternal characteristics, including cFTS results and pregnancy outcome, of pregnancies with any 22q11.2 deletion or duplication (LCR22-A to -H) and pregnancies with a classic deletion or duplication (LCR22-A to -D) diagnosed by chromosomal microarray were compared with those of a chromosomally normal reference group. A risk algorithm was developed for assessing patient-specific risks for classic 22q11.2 deletions based on NT, PAPP-A and β-hCG. Detection rates and false-positive rates at different risk cut-offs were calculated.

RESULTS

We included data on 143 pregnancies with a fetal 22q11.2 aberration, of which 97 were deletions (54 classic) and 46 were duplications (32 classic). NT was significantly increased in fetuses with a classic deletion (mean, 1.89 mm), those with any deletion (mean, 1.78 mm) and those with any duplication (mean, 1.86 mm) compared to the reference group (mean, 1.65 mm). β-hCG multiples of the median (MoM) was decreased in all 22q11.2 subgroups compared with the reference group (mean, 1.02) and reached significance in pregnancies with a classic deletion and those with any deletion (mean, 0.77 and 0.71, respectively). PAPP-A MoM was significantly decreased in pregnancies with a classic duplication and those with any duplication (mean, 0.57 and 0.63, respectively), and was significantly increased in pregnancies with a classic deletion and those with any deletion (mean, 1.34 and 1.16, respectively), compared to reference pregnancies (mean, 1.01). The screen-positive rate by cFTS was significantly increased in pregnancies with a classic deletion (13.7%), any deletion (12.5%), a classic duplication (46.9%) or any duplication (37.8%) compared to the reference group (4.5%). A risk algorithm targeting classic 22q11.2 deletions more than doubled the prenatal detection rate of classic 22q11.2 deletions, but with a substantial increase in the false-positive rate. Structural malformations were detected in 41%, 35%, 17% and 25% of the pregnancies with a classic deletion, any deletion, classic duplication or any duplication, respectively. Pregnancy loss occurred in 40% of pregnancies with a classic deletion and 5% of those with a classic duplication diagnosed prenatally or following pregnancy loss.

CONCLUSIONS

The distribution of cFTS markers in pregnancies with a classic 22q11.2 duplication resembles that of the common trisomies, with decreased levels of PAPP-A. However, classic 22q11.2 deletions are associated with increased levels of PAPP-A, which likely limits early prenatal detection using the current cFTS risk algorithm. The scope for improving early detection of classic 22q11.2 deletions using targeted risk algorithms based on NT, PAPP-A and β-hCG is limited. This demonstrates the capability, but also the limitations, of cFTS markers in detecting atypical chromosomal anomalies, which is important knowledge when designing new prenatal screening programs. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Diagnostic yield of copy number variation sequencing in fetuses with increased nuchal translucency: a retrospective study

OBJECTIVE

To assess the efficacy of copy number variation sequencing (CNV-seq) and karyotyping for prenatal detection of chromosomal abnormalities in fetuses with increased nuchal translucency.

METHODS

Amniotic fluid samples were extracted from 205 fetuses with increased nuchal translucency (NT ≥ 2.5 mm), diagnosed by ultrasound between gestational ages of 11 and 13 + 6 weeks. Karyotyping and CNV-seq were performed for detecting chromosomal abnormalities.

RESULTS

There are 40 fetuses (19.51%) showing increased NT detected with chromosomal abnormalities in karyotyping, and trisomy 21 was found to be the most common abnormalities. There are 50 fetuses (24.39%) identified with chromosomal abnormalities by CNV-seq. The detection of the applied techniques indicated that CNV-seq revealed higher chromosomal aberrations. The risk of chromosomal abnormalities was significantly increased with NT thickening, from 13.64% in the NT group of 2.5-3.4 mm, 38.64% in the NT group of 3.5-4.4 mm, and to 51.72% in the NT group of over 4.5 mm (P < 0.05). The investigated cases with increased NT with presence of soft markers in ultrasound or high risk in non-invasive prenatal testing presented chromosomal abnormalities in higher rates, comparing with those with isolated NT or low risk (P < 0.05).

CONCLUSION

The results indicated that the risk of chromosomal abnormalities was associated with the NT thickness, detected by karyotype or CNV-seq. The combination application of two analysis was efficient to reveal the possible genetic defects in prenatal diagnosis. The finding suggested that the detection should be considered with ultrasonographic soft markers, and the NT thickness of 2.5-3.4 mm could be a critical value for detecting chromosomal abnormalities to prevent the occurrence of missed diagnosis.

Uncovering the Genetic Basis of Congenital Heart Disease: Recent Advancements and Implications for Clinical Management

Congenital heart disease (CHD) is the most prevalent hereditary disorder, affecting approximately 1% of all live births. A reduction in morbidity and mortality has been achieved with advancements in surgical intervention, yet challenges in managing complications, extracardiac abnormalities, and comorbidities still exist. To address these, a more comprehensive understanding of the genetic basis underlying CHD is required to establish how certain variants are associated with the clinical outcomes. This will enable clinicians to provide personalized treatments by predicting the risk and prognosis, which might improve the therapeutic results and the patient's quality of life. We review how advancements in genome sequencing are changing our understanding of the genetic basis of CHD, discuss experimental approaches to determine the significance of novel variants, and identify barriers to use this knowledge in the clinics. Next-generation sequencing technologies are unravelling the role of oligogenic inheritance, epigenetic modification, genetic mosaicism, and noncoding variants in controlling the expression of candidate CHD-associated genes. However, clinical risk prediction based on these factors remains challenging. Therefore, studies involving human-induced pluripotent stem cells and single-cell sequencing help create preclinical frameworks for determining the significance of novel genetic variants. Clinicians should be aware of the benefits and implications of the responsible use of genomics. To facilitate and accelerate the clinical integration of these novel technologies, clinicians should actively engage in the latest scientific and technical developments to provide better, more personalized management plans for patients.

Elevated nuchal translucency, is it time to discuss the cut off?

OBJECTIVE

We aimed to evaluate pregnancy and postnatal outcomes of fetuses with NT between 95th and 99th percentile at first trimester and whether they could benefit from further investigations rather that routine scans.

METHODS

Multicenter retrospective observational study which involved all cases with NT between 95th and 99th percentile from January 2015 to December 2020. Unfavorable outcome was considered as: miscarriage or intrauterine fetal death (IUFD), chromosomal abnormality/genetic syndrome, major malformation or neurodevelopmental delay. Study population outcomes were compared with general population.

RESULTS

The rate of unfavorable outcome was 25.44% (167 out of 667). We reported: 6 (0.90%) second trimester miscarriage or IUFD, 90 (13.49%) chromosomal abnormalities/genetic syndromes, 57 (8.55%) major malformations, 13 (1.95%) cases of neurodevelopmental delay. The incidence of chromosomal abnormalities/genetic syndromes and major malformations were significantly higher (OR 6.99 (IC 95% 4.33-11.28), P < 0.001 and OR 17.77 (IC 95%7.22-43.75), P < 0.001 respectively) compared to the general population. The incidence of neurodevelopmental delay was not increased (OR of 0.64 CI 95% 0.33-1.24 P = 0.185).

CONCLUSIONS

Fetuses with NT between 95th and 99th percentile have an increased risk of pregnancy and postnatal adverse outcomes. According to our data it is reasonable to consider a lower cut of NT (NT > 95th percentile) for offering further investigations such as detailed ultrasound scan, fetal echocardiography and counseling where the option of performing fetal karyotype and CGH array should be discussed.

Prenatal whole-exome sequencing in fetuses with increased nuchal translucency

BACKGROUND

Increased nuchal translucency (NT) is associated with an increased risk for genetic disorders. The aim of this study was to investigate the value of whole-exome sequencing (WES) in detecting genetic abnormalities for fetuses with isolated first-trimester increased NT.

METHODS

After the exclusion of aneuploidies and pathogenic copy number variants (CNVs) by quantitative fluorescent polymerase chain reaction (QF-PCR) and chromosomal microarray analysis (CMA), WES was performed on 63 fetuses with isolated first-trimester increased NT (≥3.5 mm).

RESULTS

Overall, WES yielded a 4.8% (3/63) diagnostic rate for fetuses with isolated increased NT. Pathogenic variants were identified in 37.5% (3/8) fetuses that developed additional structural anomalies later in gestation, and no pathogenic variants were detected in increased NT that resolved or remained isolated throughout the pregnancy.

CONCLUSION

This study provides powerful evidence to offer prenatal WES for increased NT only when additional abnormalities are present. Early detailed ultrasound to detect emerging anomalies can help physicians offer prenatal WES to fetuses with a greater likelihood of diagnosis.

Prenatal diagnosis and perinatal outcomes of twin pregnancies disharmonious for one fetus with nuchal translucency above the 95th percentile

OBJECTIVE

To assess prenatal diagnosis and pregnancy outcomes in twin pregnancies where one fetus has nuchal translucency (NT) above the 95th percentile.

METHOD

In this retrospective analysis, 130 twin pregnancies (260 fetuses) in which one twin had an NT measurement above the 95th percentile while that of the other twin was normal were analyzed. Prenatal diagnostic results such as G bands, chromosomal microarray analysis, ultrasound findings, and pregnancy outcomes were reviewed.

RESULTS

Karyotype analysis and CMA results revealed that 15 (15.6 percent, 15/96) fetuses exhibited chromosomal abnormalities and that 13 fetuses were Variant of Uncertain Significance. Chromosome abnormalities were detected at a rate of 8.9% (5/56) in the DCT group and 25.0% (10/40) in the MCT group (p = 0.033, X2 = 4.571). 2 fetuses in DCT (3.9 percent, 2/51) and 4 fetuses in MCT (13.3 percent, 4/30) (p = 0.187) revealed structural abnormalities among the cases with normal prenatal diagnosis. Fetuses in the DCT group had an overall survival rate of 75.4 percent (95/126), whereas those in the MCT group had a survival rate of 60.4 percent (81/134) (p = 0.01, X2 = 6.636). According to the findings of Logistics regression analysis, NT thickening, maternal age and method of conception were all significant risk factors for chromosome abnormalities.

CONCLUSION

In twin pregnancies with one fetus with NT above the 95th percentile, the prevalence of fetal structural abnormalities of the MCT group and the DCT group were comparable. Pregnant women's age and mode of pregnancy are risk factors for chromosomal abnormalities.

Application of non-invasive prenatal testing in screening chromosomal aberrations in pregnancies with different nuchal translucency cutoffs

OBJECTIVE

To investigate the efficiency of non-invasive prenatal testing (NIPT) in cases with different cutoffs of nuchal translucency (NT).

METHODS

The study retrospectively analyses pregnancies with NT ≥ 2.5 mm who underwent NIPT. Results of NT, NIPT, chromosomal diagnostic and pregnancy outcomes were collected.

RESULTS

Study group was composed of 1470 single pregnancies, including 864 with NT 2.5-2.9 mm, 350 with NT 3.0-3.4 mm and 256 with NT ≥ 3.5 mm. Non-significant differences were found in the positive predictive value (PPV) of NIPT between different cutoffs of NT. There was one false positive case with NT 4.3 mm, screening for 47,XYY in NIPT showed normal in diagnostic testing. For cases with normal NIPT results, the residual risk is 1:20 (5%, 95%CI: 0.1-10.1%) in fetuses with NT 3.0-3.4 mm and 1:15 (6.5%, 95%CI: 1.4%-11.5%) in fetuses with NT ≥ 3.5 mm. These false negative cases included one trisomy 21, seven pathogenic CNVs, one uniparental disomy and one single gene disorders.

CONCLUSION

Our findings demonstrated that the PPV of NIPT for screening chromosomal aberrations were similarly in different NT cutoffs, while false positive case does exist. After normal in NIPT, risk for chromosomal aberrations remained, especially pathogenic CNV and even common trisomy. Therefore, prenatal diagnosis was recommended and CMA was suggested to apply in pregnancies with NT ≥ 3.0 mm.

Association analysis between chromosomal abnormalities and fetal ultrasonographic soft markers based on 15,263 fetuses

BACKGROUND

Soft markers are common prenatal ultrasonographic findings that indicate an increased risk for fetal aneuploidy. However, the association between soft markers and pathogenic or likely pathogenic copy number variations is still unclear, and clinicians lack clarity on which soft markers warrant a recommendation for invasive prenatal genetic testing of the fetus.

OBJECTIVE

This study aimed to provide guidance on ordering prenatal genetic testing for fetuses with different soft markers and to elucidate the association between specific types of chromosomal abnormalities and specific ultrasonographic soft markers.

STUDY DESIGN

Low-pass genome sequencing was performed for 15,263 fetuses, including 9123 with ultrasonographic soft markers and 6140 with normal ultrasonographic findings. The detection rate of pathogenic or likely pathogenic copy number variants among fetuses with various ultrasonographic soft markers were compared with that of fetuses with normal ultrasonography. The association of soft markers with aneuploidy and pathogenic or likely pathogenic copy number variants were investigated using Fisher exact tests with Bonferroni correction.

RESULTS

The detection rate of aneuploidy and pathogenic or likely pathogenic copy number variants was 3.04% (277/9123) and 3.40% (310/9123), respectively, in fetuses with ultrasonographic soft markers. An absent or a hypoplastic nasal bone was the soft marker in the second trimester with the highest diagnostic rate for aneuploidy of 5.22% (83/1591) among all isolated groups. Four types of isolated ultrasonographic soft markers, namely a thickened nuchal fold, single umbilical artery, mild ventriculomegaly, and absent or hypoplastic nasal bone, had higher diagnostic rates for pathogenic or likely pathogenic copy number variants (P<.05; odds ratio, 1.69-3.31). Furthermore, this study found that the 22q11.2 deletion was associated with an aberrant right subclavian artery, whereas the 16p13.11 deletion, 10q26.13-q26.3 deletion, and 8p23.3-p23.1 deletion were associated with a thickened nuchal fold, and the 16p11.2 deletion and 17p11.2 deletion were associated with mild ventriculomegaly (P<.05).

CONCLUSION

Ultrasonographic phenotype-based genetic testing should be considered in clinical consultations. Copy number variant analysis is recommended for fetuses with an isolated thickened nuchal fold, a single umbilical artery, mild ventriculomegaly, and an absent or a hypoplastic nasal bone. A comprehensive definition of genotype-phenotype correlations in aneuploidy and pathogenic or likely pathogenic copy number variants could provide better information for genetic counseling.

Prenatal diagnosis and early childhood outcome of fetuses with extremely large nuchal translucency

OBJECTIVE

To evaluate the prenatal and perinatal outcome of fetuses with extremely large nuchal translucency (eNT) thickness (≥ 6.5 mm).

METHODS

193 (0.61%) singleton fetuses with eNT were retrospectively included. Anomaly scan, echocardiography, and chromosomal and genetic test were included in our antenatal investigation. Postnatal follow-up was offered to all newborns.

RESULTS

Major congenital anomalies included congenital heart defect (32.6%, 63/193), hydrops fetalis (13.5%, 26/193), omphalocele (9.3%, 18/193), and skeletal dysplasia (7.8%, 15/193) et al. Abnormal karyotype was identified in 81/115 (70.4%) cases including Turner syndrome (n = 47), Trisomy 18 (n = 17), Trisomy 21 (n = 9), and Trisomy 13 (n = 3). Chromosomal microarray analysis provided informative results with 3.6% (1/28) incremental diagnostic yield over conventional karyotyping. The diagnostic yield of exome sequencing is 10.0% (2/20). There was no significant increase [Odds Ratio (OR) = 1.974; 95% confidence interval 0.863-4.516; P = 0.104] in the incidence of chromosomal defects despite the presence of other structural anomalies. Only 13 fetuses were successfully followed up and survived at term, no one was found with developmental delay or mental retardation.

CONCLUSIONS

Extremely large NT has a high risk of chromosomal abnormality. CMA and ES improve chromosomal genomic and genetic diagnosis of fetal increased NT. When cytogenetic analysis and morphology assessment are both normal, the outcome is good.

When NIPT meets WES, prenatal diagnosticians face the dilemma: genetic etiological analysis of 2,328 cases of NT thickening and follow-up of pregnancy outcomes

Objective: To assess the performance of diverse prenatal diagnostic approaches for nuchal translucency (NT) thickening and to investigate the optimal prenatal screening or diagnostic action with a NT thickening of 95th percentile-3.50 mm. Methods: A retrospective analysis of 2,328 pregnancies with NT ≥ 95th percentile through ultrasound-guided transabdominal chorionic villus sampling (CVS), amniocentesis, or cordocentesis obtained clinical samples (chorionic villi, amniotic fluid, and cord blood), and real-time quantitative fluorescent PCR (QF-PCR), chromosome karyotyping (CS), chromosome microarray analysis (CMA), or whole exome sequencing (WES) were provided to identify genetic etiologies. Results: In this study, the incidence of chromosomal defects increased with NT thickness. When NT ≥ 6.5 mm, 71.43% were attributed to genetic abnormalities. The 994 gravidas with fetal NT thickening underwent short tandem repeat (STR), CS, and CMA. In 804 fetuses with normal karyotypes, CMA detected 16 (1.99%) extra pathogenic or likely pathogenic copy number variations (CNVs). The incremental yield of CMA was only 1.16% (3/229) and 3.37% (10/297) in the group with NT 95th percentile-2.99 mm and NT 3.0-3.49 mm, separately. Among the 525 gravidas with fetal NT thickening who underwent STR, CMA, and WES, the incremental yield of WES was 4.09% (21/513). In the group of NT 95th percentile-2.99 mm, there were no additional single-nucleotide variations (SNVs) detected in WES, while in 143 cases with NT of 3.0-3.49 mm, the incremental yield of WES was 5.59% (8/143). Conclusion: In the group of NT 95th percentile-3.0 mm, since chromosomal aneuploidy and chromosomal copy number variation were the primary causes and the additional contribution of CMA and WES was not significant, we recommend NIPT-Plus for pregnant women with a NT thickening of 95th percentile-3.0 mm first. In addition, comprehensive prenatal genetic testing involving CMA and WES can benefit pregnancies with NT thickening of 3.0-3.49 mm.

[Management of isolated increased nuchal translucency: survey among the Pluridisciplinary Centers for Prenatal Diagnosis]

OBJECTIVES

The management for isolated increased nuchal translucency (NT) in the first trimester with a normal karyotype and normal Chromosomal Microarray Analysis (CMA) is not consensual. The aim was to perform a survey among the Pluridisciplinary Centers for Prenatal Diagnosis (CPDPN) in France regarding their management of increased NT in the first trimester.

METHODS

We conducted a multicenter descriptive survey between September 2021 and October 2021 among the 46 CPDPNs of France.

RESULTS

The response rate was 56.5% (n = 26/46). The NT thickness threshold for which invasive diagnosis testing is performed is 3.0mm in 23.1% of centers (n = 6/26) and 3.5mm in 76.9% of centers (n = 20/26). A CMA was performed alone in 26.9% of centers (n = 7/26) while 7.7% of centers (n = 2/26) did not perform a CMA. The gestational age for the first reference ultrasound scan was 16 to 18 WG in 88.5% of centers (n = 23/26), while it was not performed before 22 WG in 11.5% of centers (n = 3/26). Fetal echocardiography is proposed systematically in 73.1% of centers (n = 19/26).

CONCLUSION

There is heterogeneity in the management of increased NT in the first trimester among the CPDPNs in France. In case of increased NT on first trimester ultrasound scan, the NT thickness threshold for which invasive diagnosis testing is performed varies from 3.0 mm or 3.5mm depending on the center. Moreover, CMA and early reference morphological ultrasound scan between 16 and 18 WG were not systematically performed, despite the current data suggesting their interest.

Advanced maternal age: copy number variations and pregnancy outcomes

Objective: Adverse pregnancy outcomes are closely related to advanced maternal age (AMA; age at pregnancy ≥35 years). Little research has been reported on aneuploid abnormalities and pathogenic copy number variations (CNVs) affecting pregnancy outcomes in women with AMA. The purpose of this study was to assess CNVs associated with AMA in prenatal diagnosis to determine the characteristics of pathogenic CNVs and assist with genetic counseling of women with AMA. Methods: Among 277 fetuses of women with AMA, 218 (78.7%) were isolated AMA fetuses and 59 (21.3%) were non-isolated AMA fetuses and showed ultrasound anomalies from January 2021 to October 2022. Isolated AMA was defined as AMA cases without sonographic abnormalities. Non-isolated AMA was defined as AMA cases with sonographic abnormalities such as sonographic soft markers, widening of the lateral ventricles, or extracardiac structural anomalies. The amniotic fluid cells underwent routine karyotyping followed by single nucleotide polymorphism array (SNP-array) analysis. Results: Of the 277 AMA cases, karyotype analysis identified 20 chromosomal abnormalities. As well as 12 cases of chromosomal abnormalities corresponded to routine karyotyping, the SNP array identified an additional 14 cases of CNVs with normal karyotyping results. There were five pathogenetic CNVs, seven variations of uncertain clinical significance (VOUS), and two benign CNVs. The detection rate of abnormal CNVs in non-isolated AMA cases was increasing (13/59; 22%) than in isolated AMA cases (13/218; 5.96%) (p < 0.001). We also determined that pathogenic CNVs affected the rate of pregnancy termination in women with AMA. Conclusion: Aneuploid abnormalities and pathogenic CNVs affect pregnancy outcomes in women with AMA. SNP array had a higher detection rate of genetic variation than did karyotyping and is an important supplement to karyotype analysis, which enables better informed clinical consultation and clinical decision-making.

DEGUM Recommendations on Diagnostic Puncture in Prenatal Medicine

Diagnostic puncture (amniocentesis, chorionic villus sampling, and fetal blood sampling) is an essential part of prenatal diagnostics and the only established and sufficiently scientifically evaluated possibility of diagnosing genetic diseases from pregnancy-specific cells. The number of diagnostic punctures in Germany, as in other countries, has fallen significantly. This is largely due to the introduction of first-trimester screening with further detailed ultrasound examination of the fetus and the analysis of cf-DNA (cell-free DNA) from maternal blood (noninvasive prenatal test - NIPT). On the other hand, knowledge about the incidence and appearance of genetic diseases has increased. The development of modern molecular genetic techniques (microarray and exome analysis) makes a differentiated investigation of these diseases increasingly possible. The requirements for education and counseling regarding these complex correlations have thus increased. The studies performed in recent years make it clear that diagnostic puncture performed in expert centers is associated with a low risk of complications. In particular, the procedure-related miscarriage risk hardly differs from the background risk for spontaneous abortion. In 2013, the Section of Gynecology and Obstetrics of the German Society for Ultrasound in Medicine (DEGUM) published recommendations on diagnostic puncture in prenatal medicine 1. The developments described above and new findings in recent years make it necessary to revise and reformulate these recommendations. The aim of this review is to compile important and current facts regarding prenatal medical puncture (including technique, complications, genetic examinations). It is intended to provide basic, comprehensive, and up-to-date information on diagnostic puncture in prenatal medicine. It replaces the publication from 2013 1.

Position statement from the International Society for Prenatal Diagnosis on the use of non-invasive prenatal testing for the detection of fetal chromosomal conditions in singleton pregnancies

What is already known about this topic?

What does this study add?

Genetic examination for fetuses with increased nuchal translucency by exome sequencing

AIM

This retrospective study aimed to investigate the value of exome sequencing (ES) in fetuses with isolated first-trimester increased nuchal translucency (NT) and normal chromosomes.

METHODS

ES was performed on 103 fetuses with isolated first trimester increased NT and normal chromosomes. The detection rate of monogenic conditions was analyzed.

RESULTS

Diagnostic variants were detected in nine cases in which phenotypes and genotypes correlated well, two positive cases were Thanatophoric dysplasia type I, and one case was Kabuki syndrome, which had been detected in previous studies. Eight of the nine cases with diagnostic variants developed additional structural malformations later in pregnancy. Among the nine positive cases, six had a NT thickness between 95th percentile (95th-3.4 mm), and three cases with an increased NT of 3.5 mm or greater. Also, there was no statistical difference in the diagnosis of diagnostic variants in cases with or without a thickened nuchal fold (NF).

CONCLUSIONS

The diagnostic yield of prenatal ES is low for fetuses with an isolated increased NT. In addition to Noonan syndrome, there are additional genetic syndromes such as Kabuki syndrome and Thanatophoric dysplasia type I that are potentially associated with an increased NT. A cut-off of greater than the 95th percentile may be useful in case selection for ES. Whether it is clinically meaningful to monitor NF values for fetuses with isolated increased NT and normal chromosomes worth considering.

Prenatal Screening and Diagnostic Considerations for 22q11.2 Microdeletions

Diagnosis of a chromosome 22q11.2 microdeletion and its associated deletion syndrome (22q11.2DS) is optimally made early. We reviewed the available literature to provide contemporary guidance and recommendations related to the prenatal period. Indications for prenatal diagnostic testing include a parent or child with the 22q11.2 microdeletion or suggestive prenatal screening results. Definitive diagnosis by genetic testing of chorionic villi or amniocytes using a chromosomal microarray will detect clinically relevant microdeletions. Screening options include noninvasive prenatal screening (NIPS) and imaging. The potential benefits and limitations of each screening method should be clearly conveyed. NIPS, a genetic option available from 10 weeks gestational age, has a 70-83% detection rate and a 40-50% PPV for most associated 22q11.2 microdeletions. Prenatal imaging, usually by ultrasound, can detect several physical features associated with 22q11.2DS. Findings vary, related to detection methods, gestational age, and relative specificity. Conotruncal cardiac anomalies are more strongly associated than skeletal, urinary tract, or other congenital anomalies such as thymic hypoplasia or cavum septi pellucidi dilatation. Among others, intrauterine growth restriction and polyhydramnios are additional associated, prenatally detectable signs. Preconception genetic counselling should be offered to males and females with 22q11.2DS, as there is a 50% risk of transmission in each pregnancy. A previous history of a de novo 22q11.2 microdeletion conveys a low risk of recurrence. Prenatal genetic counselling includes an offer of screening or diagnostic testing and discussion of results. The goal is to facilitate optimal perinatal care.

Array study in fetuses with nuchal translucency above the 95th percentile: a 4-year observational single-centre study

PURPOSE

To evaluate the performance of chromosomal microarray analysis (CMA) in fetuses with nuchal translucency (NT) > 95th percentile. Secondary objectives were to analyze these results according to NT thickness, below or above 3.5 mm, and those without associated anomalies.

METHODS

This observational single-cohort study was conducted between 2015 and 2018 in fetuses with NT > 95th percentile. Following an invasive test, quantitative fluorescence-polymerase chain reaction (QF-PCR) was performed, and if normal, CMA was performed. Pathogenic copy number variants (CNVs), non-reported pathogenic CNV, pathogenic autosomal recessive variants and variants of unknown significance (VUS) were analysed.

RESULTS

One-hundred and sixty-two fetuses with NT > 95th percentile, normal QF-PCR and CMA were included. Amongst 128 fetuses with NT between the 95th percentile and 3.5 mm, one (0.8%) had a pathogenic CNV, four (3.1%) had non-reported pathogenic CNV, one (0.8%) had pathogenic autosomal recessive variant and 13 (10.2%) had VUS. Amongst 34 fetuses with NT ≥ 3.5 mm, four (11.8%) had pathogenic CNV, one (2.9%) had non-reported pathogenic CNV, one (2.9%) had pathogenic autosomal recessive variant and four (11.8%) had VUS. Four in 162 (2.5%) fetuses had CNVs at the chromosome 16p13.11 region. Amongst 154 fetuses without structural abnormalities and normal QF-PCR, three (1.9%) had a pathogenic CNV, 5 (3.2%) had non-reported pathogenic CNV, one (0.6%) autosomal recessive pathogenic CNV and 16 (10.4%) had VUS.

CONCLUSION

Pathogenic CNVs were found in 1% of fetuses with an NT thickness between the 95^th percentile and 3.5 mm and in 12% of fetuses with NT ≥ 3.5 mm. CNVs were found at the 16p13.11 region in 2.5% of cases.

Increased nuchal translucency with normal karyotype and genomic microarray analysis: A multicenter observational study

OBJECTIVE

To define the residual risk of morbidity-related outcome in fetuses with nuchal translucency (NT) of 3.5 mm or more after normal genetic testing and mid-trimester anomaly scan.

METHODS

A total of 114 fetuses with isolated NT of 3.5 mm or more, normal karyotype, and array-based comparative genomic hybridization (array-CGH) were included and divided in three groups: NT 3.5-4.5 mm, NT 4.5-6 mm, and NT greater than 6 mm. RASopathy testing and ultrasound follow up were performed in all fetuses. We evaluated: (1) incidence of genetic disorders; (2) incidence of structural abnormalities; (3) pregnancy outcome; (4) long-term pediatric outcome before (point 1) and after (point 2) a normal RASopathy testing and mid-trimester anomaly scan.

RESULTS

After normal karyotype and array-CGH the residual risk of morbidity-related outcome was 24.64% for NT 3.5-4.5 mm, 25% for NT 4.5-6 mm and 76.47% for NT more than 6 mm. After a normal RASopathy testing and mid-trimester anomaly scan the residual risks decreased to 7.14%, 8.69%, and 33.3% in the three groups, respectively.

CONCLUSION

In fetuses with an NT of 3.5 mm or more and both normal karyotype and array-CGH, the rate of morbidity-related outcome depends on NT size. A normal RASopathy testing and mid-trimester ultrasound are reassuring but the residual risk of morbidity-related outcome is increased compared with the general population, particularly if NT is greater than 6 mm.

Genetic aetiology distribution of 398 foetuses with congenital heart disease in the prenatal setting

AIMS

Copy number variant-sequencing (CNV-seq) and exome sequencing (ES) have been used as powerful tools in understanding the role of genetic variants in congenital heart diseases (CHDs). A few previous large cohort studies have utilized CNV-seq and ES to investigate prenatally diagnosed CHD. Here, we sought to determine the value of CNV-seq and ES for genetic evaluation of foetal CHDs.

METHODS AND RESULTS

We recruited 398 pregnant women diagnosed with CHDs between 8 January 2017 and 30 November 2020. CNV-seq and ES were performed on foetal and parent samples. CHD cases were classified following the guidelines of the International Paediatric and Congenital Cardiac Code and the Tenth and Eleventh Revisions of the International Classification of Diseases. Data on aneuploids (AUP), pathogenic CNVs (pCNVs), and single nucleotide variants (SNVs) were collected and compared, following appropriate procedures. We identified genetic abnormalities in 129 (32.41%) foetuses. These abnormalities included AUP (10.80%), pCNVs (13.32%), and SNVs (8.04%). ES analysis yielded higher SNVs in cases without AUP or pCNVs. Non-isolated CHDs were associated with higher genetic abnormalities than isolated CHDs, mainly due to AUP differences between the two groups. The prevalence of genetic defects was the highest in foetuses with atrioventricular septal defects (AVSD), left ventricular outflow tract obstruction (LVOTO), and conotruncal defects (CTD). AVSD and anomalies of atrioventricular junctions and valves were associated with AUP abnormalities. CTD, anomalies of extrapericardial arterial trunks, and anomalies of the ventricular outflow tracts were the most common CHD categories diagnosed using CNVs. The most common CHDs associated with single ventricle (SV) abnormalities were heterotaxy (Hex) (14.89%), LVOTO (14.58%), and ventricular septal defect (VSD) (26.67%, 4/15). Although the ES yields were higher than CNV-seq for VSD (44.4%, 4/9), LVOTO (20%, 7/35), Hex (14.89%, 7/47), and CTD (9.1%, 11/121), its diagnostic yield did not increase for SV (6.7%, 1/15), AVSD (3.8%, 1/26), or right ventricular obstruction defects (2.6%, 1/38). The most common mutations were observed in KMT2D, CHD7, and NOTCH1.

CONCLUSIONS

To our knowledge, this is the largest cohort study to investigate the incidence of SNVs using ES in foetal CHD. CNV-seq and ES identified genetic abnormalities in nearly 1/3 of foetal CHD cases. Thus, CNV-seq and ES can provide clinically relevant information for pregnancy management.

Perinatal prognosis in euploid fetus with cystic hygroma. Report of two clinical cases

Introduction: Cystic hygroma (CH) is a rare congenital anomaly of the lymphatic system. It is characterized by cystic lesions predominantly in the fetal neck and its prenatal diagnosis has been associated with increased perinatal mortality, aneuploidy, and congenital malformations. Case presentation: Two cases of cervical cystic hygroma diagnosed during the second trimester of gestation are presented, one of them associated with bilateral clubfoot. Both fetuses underwent karyotyping by amniocentesis, which established that both were euploid (46 XY and 46 XX), as well as fetal nuclear magnetic resonance imaging that showed no associated major malformations. In the interdisciplinary follow-up performed 1 year after birth, no findings consistent with genetic syndromes or neurodevelopmental alterations were observed in either of the 2 cases. Conclusions: CH is a marker of poor fetal prognosis; however, euploid fetuses with this condition have a better prognosis if their lesion resolves, do not progress to hydrops fetalis, and do not present other associated malformations. Euploid fetuses with CH require specific genetic studies for RASopathies, such as Noonan syndrome, which were not available in the clinical approach of the 2 cases presented; however, typical postnatal characteristics of the disease were not evident in the clinical genetic evaluation.

Does isolated nuchal translucency from 2.5 to 2.9 mm increase the risk of fetal chromosome disease?

Increased fetal nuchal translucency (NT) is a common ultrasonic manifestation during pregnancy. Many studies have confirmed that NT ≥ 3 mm is a high risk factor for adverse pregnancy outcome. However, when NT is between 2.5 and 2.9 mm, will it increase the risk of fetal chromosome abnormalities and other diseases? What is the most appropriate method for prenatal chromosome evaluation? At present, it has not been widely reported in the literature, and the conclusion is also controversial. This prospective cohort study included fetal samples from women who underwent amniocentesis from 2017 to 2020. The samples of the experimental group were fetuses with NT ≥ 2.5 mm at 11 to 13 + 6 weeks of gestation, with or without ultrasonographic anomaly. The control group contained fetal NT < 2.5 mm without ultrasonographic anomalies. All amniotic fluid samples were tested by copy number variants sequencing. In 262 fetal samples with isolated NT from 2.5 to 2.9 mm, the detection rate of aneuploidy was 3.4% (9/262), and the risk of aneuploidy was significantly higher than that of the control group (1.4%, 32/2331) (relative risk 2.5, 95% CI 1.2-5.2). The detection rates of other pathogenic/likely pathogenic copy number variants in the two groups were 0.8% (2/262) and 1.3% (31/2331), respectively, which was not statistically significant (relative risk 0.6, 95% CI 0.1-2.4). Our results showed that isolated NT from 2.5 to 2.9 mm increased the risk of fetal chromosome aneuploidy. Therefore, noninvasive prenatal screening is recommended as the first choice for prenatal chromosome evaluation in this population.

Cardiovascular Anomalies among 1005 Fetuses Referred to Invasive Prenatal Testing-A Comprehensive Cohort Study of Associated Chromosomal Aberrations

This retrospective cohort study comprehensively evaluates cardiovascular anomalies (CVAs) and associated extracardiac structural malformations (ECMs) among 1005 fetuses undergoing invasive prenatal testing at a single tertiary Polish center in the context of chromosomal aberrations detected in them by array comparative genomic hybridization (aCGH) and G-band karyotyping. The results of our study show that CVAs are among the most common malformations detected in fetuses undergoing invasive prenatal testing, as they affected 20% of all cases seen in our department. Septal defects predominated among fetuses with numerical aberrations, while conotruncal defects were the most common findings among fetuses with pathogenic copy number variants (CNVs). In 61% of cases, CVAs were associated with ECMs (the diagnosis was confirmed postnatally or in cases of pregnancy termination by means of autopsy). The most common ECMs were anomalies of the face and neck, followed by skeletal defects. In total, pathogenic chromosomal aberrations were found in 47.5% of CVAs cases, including 38.6% with numerical chromosomal aberrations. Pathogenic CNVs accounted for 14.5% of cases with CVAs and normal karyotype. Thus, our study highlights the importance of assessing the anatomy of the fetus, and of the genetic testing (preferably aCGH) that should be offered in all CVA and ECM cases.

The Largest Germline Heterozygous Deletion Encompassing Potocki-Shaffer and WAGR Syndromes Loci to Date: A Case Report

Potocki-Schaffer syndrome includes multiple exostoses, parietal foramina, and variable developmental delay/intellectual disability. It is associated with a heterozygous deletion of the 11p12p11.2 region. In some cases, the deletion extends to the WAGR locus (11p13p12). We describe here a 9-month-old girl harboring the largest germline heterozygous deletion characterized so far. Oligohydramnios and parietal foramina were noticed during pregnancy. No patient has been diagnosed before with concomitance of these two syndromes during the prenatal period. Cytogenetic diagnosis was anticipated on basis of clinical and radiological signs. Postnatal conventional karyotype confirmed an interstitial 11p deletion: 46,XX,del(11)(p11.2p15.1). Array-comparative genomic hybridization characterized a 29.6 Mb deletion. Our case illustrates the interest of high-resolution genomic approaches to correlate adequately clinical phenotypes with specific genes in suspected contiguous gene deletion syndromes.

Prenatal Diagnosis Using Chromosomal Microarray Analysis in High-Risk Pregnancies

Background: To assess the value of chromosomal microarray analysis (CMA) during the prenatal diagnosis of high-risk pregnancies. Methods: Between January 2016 and November 2021, we included 178 chorionic villi and 859 amniocentesis samples from consecutive cases at a multiple tertiary hospital. Each of these high-risk singleton pregnancies had at least one of the following indications: (1) advanced maternal age (AMA; ≥35 years; 546, 52.7%); (2) fetal structural abnormality on ultrasound (197, 19.0%); (3) high-risk first- or second-trimester Down syndrome screen (189, 18.2%), including increased nuchal translucency (≥3.5 mm; 90, 8.7%); or (4) previous pregnancy, child, or family history (105, 10.1%) affected by chromosomal abnormality or genetic disorder. Both G-banding karyotype analysis and CMA were performed. DNA was extracted directly and examined with oligonucleotide array-based comparative genomic hybridization. Results: Aneuploidies were detected by both G-banding karyotyping and CMA in 42/1037 (4.05%) cases. Among the 979 cases with normal karyotypes, 110 (10.6%) cases had copy number variants (CNVs) in CMA, including 30 (2.9%) cases with reported pathogenic and likely pathogenic CNVs ≥ 400 kb, 37 (3.6%) with nonreported VOUS, benign, or likely benign CNVs ≥ 400 kb, and 43 (4.1%) with nonreported CNVs < 400 kb. Of the 58 (5.6%) cases with aneuploidy rearrangements, 42 (4.1%) were diagnosed by both G-banding karyotyping and CMA; four inversions, six balanced translocations, and six low mosaic rates were not detected with CMA. Conclusions: CMA is an effective first step for the prenatal diagnosis of high-risk pregnancies with fetal structural anomalies found in ultrasonography or upon positive findings.

Chromosomal microarray analysis versus noninvasive prenatal testing in fetuses with increased nuchal translucency

OBJECTIVE

To evaluate if the NT value of 2.5 mm ≤ NT < 3.0 mm is an appropriate indication for CMA tests among fetuses with isolated increased NT and NIPT is more suitable instead.

METHODS

A total of 442 fetuses with NT ≥ 2.5 mm were included, in which 241 fetuses underwent karyotype. CMA tests were then carried out when cytogenic analysis showed normal chromosomes and CNV status was compared between 2.5 mm ≤ NT < 3.0 mm and ≥3.0 mm subgroups. For the NIPT evaluation, 201 of 442 fetuses with smaller increased NT (2.5 mm ≤ NT < 3.0 mm) was examined by either NIPT or karyotype.

RESULTS

Of the 241 fetuses with NT ≥ 2.5 mm, 47(19.50%) were identified by karyotype with chromosomal abnormalities. Among 194 cases with normal karyotype, CMA unraveled additional CNVs in 16(8.25%) cases, including 3(1.55%) pathogenic CNVs, 2(1.03%) likely pathogenic CNVs and 11(5.67%) VOUS. After the subgroup analysis, however, only one case (1.16%) of likely pathogenic was identified by CMA among 86 fetuses with NT between 2.5 mm and 3.0 mm, whereas the rest of 15 CNV cases were all presented in fetuses with NT ≥ 3.0 mm. For the NIPT evaluation, the detection rate of 201 fetuses with isolated increased NT between 2.5 and 3.0 mm was 3.98%, which was indifferent to karyotype with the rate of 5%. In comparison with fetuses with 2.5-3.0 mm combined with other risks, the detection rate of karyotype was 26.92%.

CONCLUSION

While no pathogenic CNVs were detected in fetuses, chromosomal aneuploidies and genomic imbalance were found to be the major type of abnormalities when NT was 2.5-3.0 mm. Therefore, our data suggested that CMA should not be recommended when fetuses with an NT value less than 3.0 mm. Instead, NIPT with similar rate of detection as karyotype was recommended for fetuses with isolated increased NT between 2.5 and 3.0 mm.

Antenatal counselling for prospective parents whose fetus has a neurological anomaly: part 2, risks of adverse outcome in common anomalies

After diagnosis of a fetal neurological anomaly, prospective parents want to know the best and worst-case scenarios and an estimation of the risk to their infant of having an atypical developmental outcome. The literature on developmental outcomes for fetal neurological anomalies is poor: studies are characterized by retrospective design, small sample size, often no standardized assessment of development, and differing definitions of anomalies. This review provides an aide-memoir on the risks of adverse neurodevelopmental outcome for ventriculomegaly, cortical anomalies, microcephaly, macrocephaly, agenesis of the corpus callosum, posterior fossa anomalies, and myelomeningocele, to assist healthcare professionals in counselling. The data in this review should be used alongside recommendations on counselling and service design described in part 1 to provide antenatal counselling.

Diagnostic yield of next-generation sequencing in fetuses with isolated increased nuchal translucency: systematic review and meta-analysis

OBJECTIVE

To determine the diagnostic yield of exome or genome sequencing (ES/GS) over chromosomal microarray analysis (CMA) in fetuses with increased nuchal translucency (NT) and no concomitant anomalies.

METHODS

This systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. PubMed, Scopus and Web of Science were searched for studies describing ES/GS in fetuses with isolated increased NT. Inclusion criteria were: (1) study written in English; (2) more than two fetuses with increased NT > 99^th percentile and no concomitant anomalies; and (3) a negative CMA result considered as the reference standard. Only positive variants identified on ES/GS that were classified as likely pathogenic or pathogenic and determined to be causative of the fetal phenotype were considered. Risk was assessed as the pooled effect size by single-proportion analysis using random-effects modeling (weighted by inverse of variance).

RESULTS

Eleven studies reporting on the diagnostic yield of ES/GS in fetuses with isolated increased NT > 99^th percentile were identified and included 309 cases. All studies were high quality according to Standards for Reporting of Diagnostic Accuracy. Overall, a pathogenic or likely pathogenic variant was identified on ES/GS in 15 fetuses, resulting in a pooled incremental yield of 4% (95% CI, 2-6%). Six (40%) of these fetuses had NT of 5 mm or more. The observed inheritance pattern was autosomal dominant in 12 cases, including four fetuses with Noonan syndrome, autosomal recessive in two cases and X-linked in one case.

CONCLUSIONS

There is a 4% incremental diagnostic yield of ES/GS over CMA in fetuses with increased NT > 99^th percentile without a concomitant anomaly. It is unclear whether a NT cut-off higher than 3.5 mm may be more useful in case selection for ES/GS. © 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.

Trends in Non-invasive Prenatal Screening and Invasive Testing in Denmark (2000-2019) and Israel (2011-2019)

Introduction: Following the wide distribution of non-invasive prenatal genetic screening (NIPS), numerous studies have reported a decline in total invasive tests in the recent years, up to 50–70% in some countries. However, in Denmark and Israel we have not experienced these declines. The objective of our study was to evaluate the trends in NIPS and chromosomal microarray analysis (CMA) use in Denmark and Israel.

Methods: This retrospective study was performed by data acquisition from the Danish Cytogenetics Central Registry throughout the years 2000–2019, and Israeli Public Health Services, Ministry of Health computerized database (from 2011).

Results: Of the 1,243,956 live births registered in Denmark over the years 2000–2019, a relatively steady level of invasive testing around 6% was noted since 2004, as opposed to 13.0% in Israel based on 1,594,962 live births between 2011 and 2019. The average uptake of NIPS was 1.1 ± 0.5% in Denmark vs. 4.3% in Israel (2013–2019). Relatively steady rates of invasive testing were noted in both countries, compared to a slight decline in NIPS in the recent years.

Discussion: The recent decrease in the rates of invasive testing in the NIPS era was not observed in Denmark or in Israel. These results imply that Danish and Israeli women and/or health providers might favor the high resolution and yield of CMA testing over the non-invasiveness of NIPS. We explore and discuss this phenomenon, based on five central factors.

Isolated Increased Nuchal Translucency in First Trimester Ultrasound Scan: Diagnostic Yield of Prenatal Microarray and Outcome of Pregnancy

Background: Increased nuchal translucency (NT) is associated with aneuploidy. When the karyotype is normal, fetuses are still at risk for structural anomalies and genetic syndromes. Our study researched the diagnostic yield of prenatal microarray in a cohort of fetuses with isolated increased NT (defined as NT ≥ 3.5 mm) and questioned whether prenatal microarray is a useful tool in determining the adverse outcomes of the pregnancy. Materials and Methods: A prospective study was performed, in which 166 women, pregnant with a fetus with isolated increased NT (ranging from 3.5 to 14.3 mm with a mean of 5.4 mm) were offered karyotyping and subsequent prenatal microarray when karyotype was normal. Additionally, all ongoing pregnancies of fetuses with normal karyotype were followed up with regard to postnatal outcome. The follow-up time after birth was maximally 4 years. Results: Totally, 149 of 166 women opted for prenatal testing. Seventy-seven fetuses showed normal karyotype (52%). Totally, 73 of 77 fetuses with normal karyotype did not show additional anomalies on an early first trimester ultrasound. Totally, 40 of 73 fetuses received prenatal microarray of whom 3 fetuses had an abnormal microarray result: two pathogenic findings (2/40) and one incidental carrier finding. In 73 fetuses with an isolated increased NT, 21 pregnancies showed abnormal postnatal outcome (21/73, 28.8%), 29 had a normal outcome (29/73, 40%), and 23 were lost to follow-up (23/73, 31.5%). Seven out of 73 live-born children showed an adverse outcome (9.6%). Conclusions: Prenatal microarray in fetuses with isolated increased NT had a 5% (2/40) increased diagnostic yield compared to conventional karyotyping. Even with a normal microarray, fetuses with an isolated increased NT had a 28.8% risk of either pregnancy loss or an affected child.

Reexamining the optimal nuchal translucency cutoff for diagnostic testing in the cell-free DNA and microarray era: results from the Victorian Perinatal Record Linkage study

BACKGROUND

The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine recently recommended offering genetic counseling and diagnostic testing for enlarged nuchal translucency at ≥3.0 mm, regardless of previous negative screening with noninvasive prenatal testing.

OBJECTIVE

This study aimed to perform a population-based, individual record linkage study to determine the optimal definition of an enlarged nuchal translucency for the detection of atypical chromosome abnormalities.

STUDY DESIGN

This was a retrospective study of women resident in Victoria, Australia, undergoing combined first-trimester screening during the 24-month period from January 2015 to December 2016. Linkages between statewide results for combined first-trimester screening, prenatal diagnostic procedures, and postnatal cytogenetic results from products of conception and infants up to 12 months of age were used to ascertain the frequency and type of chromosome abnormality by gestation and nuchal translucency measurement. An atypical chromosome abnormality was defined as any major chromosome abnormality other than whole chromosome aneuploidy involving chromosomes 21, 18, 13, X, and Y.

RESULTS

Of the 81,244 singleton pregnancies undergoing combined first-trimester screening, 491 (0.60%) had a nuchal translucency of ≥3.5 mm, 534 (0.66%) had a nuchal translucency of 3.0 to 3.4 mm, and 80,219 (98.74%) had a nuchal translucency of < 3.0 mm. When grouped by nuchal translucency multiples of the median (MoM), 192 (0.24%) had a nuchal translucency of ≥3.0 MoM, 513 (0.63%) had a nuchal translucency of 1.9 to 2.9 MoM, and 80,539 (99.13%) had a nuchal translucency of <1.9 MoM. A total of 1779 pregnancies underwent prenatal or postnatal diagnostic testing, of which 89.60% were performed by whole-genome single-nucleotide polymorphism chromosomal microarray. The frequency of total major chromosome abnormalities was significantly higher in the group with a nuchal translucency of ≥3.5 mm (147 of 491, 29.94%) than the group with a nuchal translucency of 3.0 to 3.4 mm (21 of 534, 3.93%) or a nuchal translucency of <3.0 mm (71 of 80,219, 0.09%) (P<.001). There were 93 atypical chromosome abnormalities in the total screened cohort. The frequency of an atypical chromosome abnormality was 4.07% (95% confidence interval, 2.51-6.22), 0.37% (95% confidence interval, 0.05-1.35), and 0.09% (95% confidence interval, 0.07-0.11) in the groups with a nuchal translucency of ≥3.5 mm, 3.0 to 3.4 mm, and <3.0 mm, respectively. The frequency of atypical chromosome abnormalities was 4.69% (95% confidence interval, 2.17-8.71), 2.53% (95% confidence interval, 1.36-4.29), and 0.09% (95% confidence interval, 0.07-0.11) in the groups with a nuchal translucency of ≥3.0 MoM, 1.9 to 2.9 MoM, and <1.9 MoM, respectively. When defining thresholds for offering diagnosis with chromosomal microarray at 11 to 13 weeks, both a nuchal translucency threshold of 1.9 MoM and a fixed threshold of 3.0 mm captured 22 of 93 fetuses (23.7%) with an atypical chromosome abnormality. Of these, 50.0% had a coexisting fetal abnormality on ultrasound. However, the gestation-specific threshold of 1.9 MoM had a better specificity than 3.0 mm. The positive predictive value of an enlarged nuchal translucency for any atypical chromosome abnormality was 1 in 47 for nuchal translucency of >3.0 mm and 1 in 32 for nuchal translucency of >1.9 MoM. Our nuchal translucency threshold of 1.9 MoM captured 0.87% of fetuses, thus approximating the 99th centile.

CONCLUSION

A gestational age-adjusted nuchal translucency threshold of 1.9 MoM or 99th centile is superior to the fixed cutoff of 3.0 mm for the identification of atypical chromosome abnormalities. The risk of an atypical chromosome abnormality in a fetus with an enlarged nuchal translucency is more than tripled in the presence of an additional ultrasound abnormality.

How genomics is changing the practice of prenatal testing

New genomic laboratory technology namely microarrays and high throughput sequencing (HTS) as well as a steady progress in sonographic image capture and processing have changed the practice of prenatal diagnosis during the last decade fundamentally. Pregnancies at high risk for common trisomies are reliably identified by non-invasive prenatal testing (NIPT) and expert sonography has greatly improved the assessment of the fetal phenotype. Preconceptional comprehensive carrier screening using HTS is available for all parents, if they should wish to do so. A definite fetal diagnosis, however, will still require invasive testing for most conditions. Chromosomal microarrays (CMA) have greatly enhanced the resolution in the detection of chromosome anomalies and other causal copy number variations (CNV). Gene panel or whole exome sequencing (WES) is becoming the routine follow up of many anomalies detected by ultrasound after CNVs have been excluded. The benefits and limitations of the various screening as well as diagnostic options are perceived as complex by many who find it challenging to cope with the need for immediate choices. The communication of facts to ensure an informed decision making is obviously a growing challenge with the advent of the new genomic testing options. This contribution provides an overview of the current practice and policies in Switzerland.

The Term Newborn: Postnatal Screening and Testing

Prenatal genetic screening, including evaluation for inherited genetic disorders, aneuploidy risk assessment, and sonographic assessment, combined with a thorough newborn examination and standard newborn screening, including blood, hearing, and congenital heart disease screening, can reveal conditions requiring further evaluation after delivery. Abnormal prenatal or newborn screening results should prompt additional diagnostic testing guided by maternal fetal medicine, perinatal genetics, or pediatric specialists.

Increased nuchal translucency after low-risk noninvasive prenatal testing: What should we tell prospective parents?

Three decades ago, the observation that first trimester fetuses with excess fluid accumulation at the back of the neck were more likely to be aneuploid, gave rise to a new era of prenatal screening. The nuchal translucency (NT) measurement in combination with serum biomarkers and maternal age, resulted in the first trimester combined screening (FTCS) program. The introduction of noninvasive prenatal testing (NIPT) over the past decade has introduced the option for parents to receive highly sensitive and specific screening information for common trisomy from as early as 10 weeks gestation, altering the traditional pathway FTCS pathway. The retention of the 11-13-week NT ultrasound remains important in the detection of structural anomalies; however, the optimal management of pregnancies with a low-risk NIPT result and an isolated increased NT measurement in an era of advanced genomic testing options is a new dilemma for clinicians. For parents, the prolonged period between the initial diagnosis in first trimester, and prognostic information at each successive stage of investigations up to 22-24 weeks, can be emotionally challenging. This article addresses the common questions from parents and clinicians as they navigate the uncertainty of having a fetus diagnosed with an increased NT after a low-risk NIPT result and presents suggested approaches to management.

Have maternal or paternal ages any impact on the prenatal incidence of genomic copy number variants associated with fetal structural anomalies?

The objective of this study was to determine whether maternal or paternal ages have any impact on the prenatal incidence of genomic copy number variants (CNV) in fetuses with structural anomalies. We conducted a non-paired case-control study (1:2 ratio) among pregnancies undergoing chromosomal microarray analysis (CMA) because of fetal ultrasound anomalies, from December 2012 to May 2020. Pregnancies with any pathogenic copy number variant (CNV), either microdeletion or microduplication, were defined as cases. Controls were selected as the next two pregnancies with the same indication for CMA but with a normal result. Logistic regression was used, adjusting by use of assisted reproductive technology (ART) and parental smoking. Stratified analysis was performed according to CNV type (de novo/inherited and recurrent/non-recurrent). The study included 189 pregnancies: 63 cases and 126 controls. Mean maternal age in cases was 33.1 (SD 4.6) years and 33.9 (SD 6.0) years in controls. Mean paternal mean age was 34.5 (SD 4.8) years in cases and 35.8 (SD 5.8) years in controls. No significant differences in maternal or paternal age were observed, neither in stratified analysis according to the CNV type. Moreover, the proportion of cases were not significantly different between non-advanced and advanced ages, either considering paternal or maternal ages. The presence of pathogenic CNV at CMA in fetuses with structural anomalies was not found to be associated with advanced paternal or maternal age.

Identification of a New Variant of PUF60 Gene: Case Presentation and Literature Review

BACKGROUND/AIM

The aim of the study was to report the case of a 5-month-old boy with a complex prenatal and neonatal symptomatology diagnosed with a "de novo" pathogenic variant of PUF60 gene.

CASE REPORT

Our hospital, undertook the antenatal and postnatal care of a 27-year-old pregnant lady. This was her second baby with a previously healthy boy. During her routine first-trimester anomaly scan, increased nuchal translucency was noticed. Multiple anomalies were seen throughout her subsequent antenatal visits. This triggered a sequence of tests, examinations and differential diagnosis. The final diagnosis was made at 5 months postpartum following the result of the whole exome sequence, which described a variant of unknown clinical significance (VUS, class 3 variant) in the PUF60 gene. We are mindful that changing the classification of a variant of unknown significance is challenging and requires supporting and robust criteria. Considering clinical symptomatology produced by the pathogenic mutation in the PUF gene, the identified c.1640A>G variant may be categorized as likely pathogenic.

CONCLUSION

Our case adds new insights on the pathology and the underlying process involved in the PUF60 variant spectrum disorders. It also highlights the limits of current prenatal tests.

Practice patterns of prenatal and perinatal testing in Canadian cytogenetics laboratories

OBJECTIVE

To survey patterns of practice in Canadian cytogenetics laboratories and evaluate whether newer technologies have influenced testing algorithms for the detection of common aneuploidies and other genomic imbalances in the prenatal and perinatal settings.

METHODS

Cytogenetics laboratories across Canada were invited to participate in two patterns-of-practice surveys: one in 2016 and one in 2019. They were asked to identify the prenatal and perinatal specimen types tested at their facility and which testing methods were used for initial testing and for follow-up.

RESULTS

All clinical laboratories performing prenatal testing offer rapid aneuploidy detection (RAD). Most laboratories also offer microarray analysis. A positive result is either followed up by karyotyping or no further testing is performed. For prenatal samples, a negative result may be followed up by microarray or karyotyping and is dependent on the reason for referral. For perinatal samples, availability of microarray to follow up a negative result is increasing.

CONCLUSIONS

Since 2016, the availability of RAD as a first-line test in Canadian cytogenetics laboratories remains consistent, while microarray has become the preferred follow-up testing method over traditional karyotyping following a normal RAD result. Despite a universal healthcare system, disparities in prenatal and perinatal cytogenetic testing algorithms are apparent.

Risk of Clinically Significant Chromosomal Microarray Analysis Findings in Fetuses With Nuchal Translucency From 3.0 mm Through 3.4 mm

OBJECTIVE

To examine the risk of clinically significant chromosomal microarray analysis findings in fetuses with nuchal translucency from 3.0-3.4 mm. In addition, we aimed to define the yield of noninvasive prenatal testing (NIPT) in such pregnancies.

METHODS

This retrospective cohort study included results of all chromosomal microarray analysis tests performed owing to a nuchal translucency measurement from 3.0-3.4 mm, without ultrasonographic anomalies, retrieved from the Israeli Ministry of Health computerized database. Rates of clinically significant (pathogenic and likely pathogenic) microarray findings were compared with a previously published local control population, encompassing 2,752 fetuses with normal ultrasound findings and nuchal translucency less than 3.0 mm.

RESULTS

Overall, 619 chromosomal microarray analyses were performed owing to isolated nuchal translucency from 3.0-3.4 mm. Of these, 29 (4.7%) cases had clinically significant copy number variants, a significantly higher risk compared with control-group pregnancies (relative risk 3.3, 95% CI 2.6-7.2). Divided by tenths of millimeters, the risk for abnormal chromosomal microarray analysis findings remained significantly increased, except for the subgroup of 198 fetuses with nuchal translucency measurements of 3.0 mm. Noninvasive prenatal testing for the five common chromosome aneuploidies would have missed 41.4% of the abnormal copy number variants-1.9% of overall cases, or 1 in 52 fetuses with nuchal translucency from 3-3.4 mm. Genome-wide NIPT, as well as traditional karyotyping, could have missed an abnormal finding in 9 of 619 (1.5%), or 1 in 69 fetuses.

CONCLUSION

Our outcomes show that the rate of abnormal chromosomal microarray analysis findings in fetuses with nuchal translucency from 3.1-3.4 mm is significantly higher compared with fetuses with normal ultrasound findings.

The role of chromosomal microarray and exome sequencing in prenatal diagnosis

PURPOSE OF REVIEW

Advancements in technologies have revolutionized prenatal diagnosis. Chromosomal microarray analysis (CMA) became a proven method and was implemented to detect gains and losses of DNA and absence of heterozygosity across the genome. Next-generation sequencing technologies have brought opportunities and challenges to genetic testing. Exome sequencing detects single-nucleotide variants (SNVs) across the exome and its prenatal application is an emerging field. We reviewed the literature to define the role of CMA and exome sequencing in prenatal diagnosis.

RECENT FINDING

The application of exome sequencing in genetic diagnosis shows increased diagnostic yield and could be potentially implemented for prenatal diagnosis of fetuses with one or more ultrasound structural abnormalities or suspected monogenetic conditions. Although CMA is a gold standard for copy number variant (CNV) detection, large clinical cohort studies emphasized integrated CNV and SNV analyses for precise molecular diagnosis. Recent studies also suggest low-pass genome sequencing-based CNV detection can identify genome-wide imbalances at higher resolutions.

SUMMARY

Data suggest exome sequencing for SNVs and CMA for CNV detection are the most effective approach for prenatal genetic diagnosis. Emerging evidences show genome sequencing has the potential to replace CMA and even exome sequencing to become a comprehensive genetic test in the clinical diagnostic laboratory.

Chances and Challenges of New Genetic Screening Technologies (NIPT) in Prenatal Medicine from a Clinical Perspective: A Narrative Review

In 1959, 63 years after the death of John Langdon Down, Jérôme Lejeune discovered trisomy 21 as the genetic reason for Down syndrome. Screening for Down syndrome has been applied since the 1960s by using maternal age as the risk parameter. Since then, several advances have been made. First trimester screening, combining maternal age, maternal serum parameters and ultrasound findings, emerged in the 1990s with a detection rate (DR) of around 90-95% and a false positive rate (FPR) of around 5%, also looking for trisomy 13 and 18. With the development of high-resolution ultrasound, around 50% of fetal anomalies are now detected in the first trimester. Non-invasive prenatal testing (NIPT) for trisomy 21, 13 and 18 is a highly efficient screening method and has been applied as a first-line or a contingent screening approach all over the world since 2012, in some countries without a systematic screening program. Concomitant with the rise in technology, the possibility of screening for other genetic conditions by analysis of cfDNA, such as sex chromosome anomalies (SCAs), rare autosomal anomalies (RATs) and microdeletions and duplications, is offered by different providers to an often not preselected population of pregnant women. Most of the research in the field is done by commercial providers, and some of the tests are on the market without validated data on test performance. This raises difficulties in the counseling process and makes it nearly impossible to obtain informed consent. In parallel with the advent of new screening technologies, an expansion of diagnostic methods has begun to be applied after invasive procedures. The karyotype has been the gold standard for decades. Chromosomal microarrays (CMAs) able to detect deletions and duplications on a submicroscopic level have replaced the conventional karyotyping in many countries. Sequencing methods such as whole exome sequencing (WES) and whole genome sequencing (WGS) tremendously amplify the diagnostic yield in fetuses with ultrasound anomalies.

Fetal Cystic Hygroma Associated with Terminal 2p25.1 Duplication and Terminal 3p25.3 Deletion: Cytogenetic, Fluorescent in Situ Hybridization and Microarray Familial Characterization of Two Different Chromosomal Structural Rearrangements

We report a prenatally diagnosed case of partial trisomy 2p and partial monosomy 3p, resulting from unbalanced translocation (2;3)(p25.1;p25.3) of paternal origin. Parents were non consanguineous Caucasians, with familial history of recurrent miscarriages on the father’s side. Detailed sonographic examination of the fetus showed a septated cystic hygroma measuring 6 mm at 13 weeks’ gestation. Karyotyping and fluorescent in situ hybridization (FISH) analysis of cultured amniotic fluid cells revealed an unbalanced translocation der(3)t(2;3)(p25.1; p25.3) and apparently balanced inv(3)(p13p25.3) in a fetus. Parental cytogenetic evaluation using karyotyping and FISH analysis showed the presence of both a balanced translocation and a paracentric inversion in father t(2;3) (p25.1;p25.3) inv(3)(p13p25.3). Microarray analysis showed a 11.6 Mb deletion at 3p26.3-p25.3 and duplication of 10.5 Mb at the 2p25.3-p25 region. The duplicated region at 2p25.1p25.3 contains 45 different genes, where 12 are reported as OMIM morbid genes with different phenotypical implications. The deleted region at 3p26.3-p25.3 contains 65 genes, out of which 27 are OMIM genes.

Three of these (CNTN4, SETD5 and VHL) were curated by Clingene Dosage Gene Map and were given a high haplo-insufficiency score. Genes affected by the unbalanced translocation could have contributed to some specific phenotypic changes of the fetus in late pregnancy. The application of different cytogenetic methods was essential in our case, allowing the detection of different types of structural chromosomal aberrations and more thorough genetic counseling for future pregnancies.

First prenatal case of Noonan syndrome with SOS2 mutation: Implications of early diagnosis for genetic counseling

RASopathies are a group of syndromes with partially overlapping clinical features caused by germline mutations of the RAS/MAPK signaling pathway genes. The most common disorder is Noonan syndrome (NS; MIM 163950). We report the first prenatal case of NS with SOS2 (NM_006939.4) mutation in a euploid fetus with a severe increase in nuchal translucency (NT > 12 mm). Trio-based custom next-generation sequencing detected a de novo heterozygous missense mutation in the SOS2 gene: c.800 T > A (p.Met267Lys). Owing to the marked variable expressivity of NS and the scarcity of SOS2 mutation-related NS cases reported in the literature, it is difficult to provide appropriate genetic counseling. Several issues such as the best management technique and optimal NT cutoff have been discussed. In addition, in general, the fine balance between the advantages of an early prenatal diagnosis and the challenge of determining if the detected gene variant is pathogenic and, primarily, the stress of the counselees when providing a genetic counseling with limited information on the prenatal phenotype have been discussed. A prenatal path comprising examinations and multidisciplinary counseling is essential to support couples in a shared decision-making process.

Abnormal nuchal translucency followed by normal microarray analysis is associated with placental pathology-related complications

OBJECTIVE

Identify placental pathology-related complications, labor and neonatal outcomes in pregnancies complicated by pathological nuchal translucency (NT) with normal microarray analysis.

METHODS

A retrospective study in which all women with singleton pregnancy who demonstrated NT above 3 mm and a normal microarray analysis were matched to women with normal NT and a normal microarray analysis (2013-2019) in a single tertiary academic center. The following placental pathology-related parameters were measured: preeclampsia, oligohydramnios, suspected intrauterine growth restriction, abnormal Doppler studies or small for gestational age (SGA) neonates. The primary outcome was defined as a composite of complications related to placental pathology including preeclampsia and SGA neonate. Secondary outcomes were labor complications and neonatal morbidity.

RESULTS

A total of 185 women were included in the study: of them, 47 presented an abnormal NT (study group) and 138 presented normal NT (controls). Groups did not significantly differ in baseline characteristics. Regarding primary outcome, all placental-related complications frequencies were higher in the study group, with a composite rate of 17.02% versus 6.52% in controls (p = 0.042%). Secondary outcomes did not differ between groups.

CONCLUSIONS

Abnormal NT measurement presented in pregnancies with normal fetal microarray analysis is associated with higher rates of placental-related complications.