Cell-free DNA screening for prenatal detection of 22q11.2 deletion syndrome

Advances in Prenatal Cell-Free DNA Screening for Dominant Monogenic Conditions: A Review of Current Progress and Future Directions in Clinical Implementation

Prenatal cell-free DNA (cfDNA) screening has advanced significantly, extending beyond detecting aneuploidies to sub-chromosomal copy number variations. However, its application for screening dominant single-gene conditions, often caused by de novo variants, remains underutilized in the general obstetric population. This study reviews recent data and experience on prenatal cfDNA screening for dominant monogenic conditions using multiple-gene panels, highlighting its potential to enhance early detection and management of genetic disorders. Integrating comprehensive cfDNA screening into routine prenatal care could complement current imaging techniques and standard prenatal cfDNA screening, which may overlook pre-symptomatic fetuses with dominant monogenic conditions in early gestation. Despite promising initial results, further research is needed to confirm the clinical validity and utility of cfDNA screening for these conditions. Larger and more diverse studies are necessary to assess the broader applicability of this technology. In addition, key challenges such as access, genetic counseling, ethical considerations, and policy development need to be addressed. A comprehensive approach, including rigorous test design, informed consent, and robust counseling, is essential for the successful adoption of expanded cfDNA screening, ultimately improving clinical outcomes.

BinDel: Detecting Clinically Relevant Fetal Genomic Microdeletions Using Low-Coverage Whole-Genome Sequencing-Based NIPT

OBJECTIVE

Clinically pathogenic chromosomal microdeletions cause severe genetic disorders. Motivated by the absence of reliable screening of microdeletions during the first-trimester screening, we developed BinDel, a software tool to determine the risk of clinically relevant pathogenic fetal microdeletions from low-coverage whole-genome-sequencing (WGS) based NIPT data.

METHODS

We developed novel computational software that employs a targeted approach with region-specific normalisation and calling procedures to detect microdeletion risk in predefined chromosomal regions. The software was developed using 500 NIPT samples and validated on an additional 84 samples, including 34 rare fetal microdeletions confirmed both pre- and postnatally.

RESULTS

BinDel correctly identified 30 out of 34 samples with microdeletions, with only three false-positive calls among 50 euploid samples, all latter originating from the Williams-Beuren and Prader-Willi/Angelman syndrome-associated microdeletion regions.

CONCLUSIONS

We confirmed BinDel's feasibility for integrating microdeletion analysis into routine NIPT protocol. This work stands as a unique contribution to prenatal microdeletion screening, providing a novel and readily available software tool that was validated with a large set of actual microdeletion samples, positioning it as the first of its kind in the field. BinDel is available at https://github.com/seqinfo/BinDel.

Best Practice & Research clinical obstetrics & gynaecology

Screening for fetal genetic disorders is a focus of prenatal care. Cell free DNA (cfDNA) screening for aneuploidies became available in 2011. Initially available only to high-risk individuals, this test is now standard of care in many settings. cfDNA screening has expanded to include sex chromosomal aneuploidies, copy number variants, and rare autosomal trisomies. However, the positive predictive value for rarer conditions is significantly lower, the number of conditions tested for is small, and abnormal results may occur due to maternal genetic findings. The field is changing quickly, and national recommendations for the use of cfDNA in screening for fetal and maternal diseases varies internationally. Research on the performance of screening for many different genetic disorders using cfDNA is ongoing, and suggests that this methodology may allow for testing of a much greater number of genetic conditions. Additionally, improved understanding of the cfDNA molecules themselves may provide additional insights: both high and low fetal fractions may suggest adverse pregnancy outcomes, and characteristics of the fragments themselves may help distinguish tissue of origin.

Artificial intelligence and machine learning in cell-free-DNA-based diagnostics

The discovery of circulating fetal and tumor cell-free DNA (cfDNA) molecules in plasma has opened up tremendous opportunities in noninvasive diagnostics such as the detection of fetal chromosomal aneuploidies and cancers and in posttransplantation monitoring. The advent of high-throughput sequencing technologies makes it possible to scrutinize the characteristics of cfDNA molecules, opening up the fields of cfDNA genetics, epigenetics, transcriptomics, and fragmentomics, providing a plethora of biomarkers. Machine learning (ML) and/or artificial intelligence (AI) technologies that are known for their ability to integrate high-dimensional features have recently been applied to the field of liquid biopsy. In this review, we highlight various AI and ML approaches in cfDNA-based diagnostics. We first introduce the biology of cell-free DNA and basic concepts of ML and AI technologies. We then discuss selected examples of ML- or AI-based applications in noninvasive prenatal testing and cancer liquid biopsy. These applications include the deduction of fetal DNA fraction, plasma DNA tissue mapping, and cancer detection and localization. Finally, we offer perspectives on the future direction of using ML and AI technologies to leverage cfDNA fragmentation patterns in terms of methylomic and transcriptional investigations.

Routine Prenatal cfDNA Screening for Autosomal Dominant Single-Gene Conditions

BACKGROUND

Genetic screening has advanced from prenatal cell-free DNA (cfDNA) screening for aneuploidies (cfDNA-ANP) to single-gene disorders (cfDNA-SGD). Clinical validation studies have been promising in pregnancies with anomalies but are limited in the general population.

METHODS

Chart review and laboratory data identified pregnancies with cfDNA-SGD screening for 25 autosomal dominant conditions at our academic center. Screening was identified as routine by International Classification of Diseases (ICD) 10 codes and chart review. Ultrasound anomalies or known family history of a condition on the panel were excluded. Retrospective chart review investigated test concordance, outcomes, and phenotypes.

RESULTS

cfDNA-SGD was completed for 3480/37 050 (9.4%) pregnancies, of which 2745 (78.9%) were for routine screening. Fourteen (0.51%, 14/2745) had high-risk results defined as pathogenic/likely pathogenic (P/LP) variants: 6 (0.22%) likely fetal variants, and 8 (0.29%) maternal variants with 50% risk for fetal inheritance. Diagnostic testing detected 6/6 fetal and 6/8 maternal cfDNA-SGD variants (2/8 pregnant individuals declined testing but had clinical features on physical exam). Variants were detected in 11/14 pregnancies/newborns and in 9/14 (64.3%) parents/gamete donors. There were no false positives identified by cfDNA-SGD; however, 2 variants were discrepantly classified between the cfDNA-SGD and diagnostic testing laboratories. All pregnancies had normal imaging and 9 had mild postnatal phenotypes. Three terminated pregnancy following diagnostic testing.

CONCLUSIONS

Our study demonstrated that 0.51% of routine cfDNA-SGD was high risk, prompting comprehensive evaluation for pregnancies and parents. Routine cfDNA-SGD allowed for early identification and intervention, but raises counseling challenges due to variable expressivity, limited genotype-phenotype correlations, and discrepant variant classification.

The efficacy of expanded non-invasive prenatal testing (NIPT) in a high-risk twin pregnancies cohort

INTRODUCTION

Our objective was to evaluate the efficacy of expanded non-invasive prenatal testing (NIPT) that includes both trisomies and copy number variants (CNVs) in high-risk twin pregnancies.

MATERIAL AND METHODS

A prospective, double-blinded cohort study was conducted, enrolling 73 high-risk twin pregnancies characterized by increased risk of genetic disorders due to factors such as increased nuchal translucency, structural anomalies, fetal growth restriction, and other factors associated with chromosomal abnormality. Participants underwent invasive karyotyping and chromosomal microarray analysis, alongside separate expanded NIPT for research purposes. The sensitivity, specificity, positive predictive value, and negative predictive value of expanded NIPT were calculated.

RESULTS

The cohort included 24 monochorionic and 49 dichorionic twin pregnancies. The median cell-free fetal DNA concentration in expanded NIPT was 16.7% (range 3.86%-49.1%), with a test failure rate of 1.4% (1/73). High-risk findings for trisomy 21/13/18 were identified in five cases (6.8%), Turner syndrome in one case (1.4%), and CNVs indicative of high risk for clinically significant microdeletion/microduplication syndromes (MMS) in ten cases (13.7%). Of these, 56 cases (76.7%) tested NIPT negative, revealing one false-negative for 45, X and five false-negatives for CNVs. Expanded NIPT achieved a detection rate of 100% (5/5) for trisomy 21/13/18 with a false-positive rate of 0% (0/5), a detection rate of 33.3% (1/3) for sex chromosome abnormalities with a false-positive rate of 0% (0/3), and a detection rate of 66.7% (4/6) for MMS with a false-positive rate of 3.0% (2/67). The positive predictive values for trisomy T21/13/18, sex chromosome abnormalities, and known MMS were 100% (5/5), 100% (1/1), and 66.7% (4/6) in the expanded NIPT, respectively.

CONCLUSIONS

The expanded NIPT demonstrated high detection rates for common trisomies and moderate detection rates for prenatal MMS in high-risk twin pregnancies. Further studies with large sample sizes in low-risk populations are needed.

High positive predictive value 22q11.2 microdeletion screening by prenatal cell-free DNA testing that incorporates fetal fraction amplification

OBJECTIVE

22q11.2 deletion syndrome (DS) is a serious condition with a range of features. The small microdeletion causing 22q11.2DS makes it technically challenging to detect using standard prenatal cfDNA screening. Here, we assess 22q11.2 microdeletion clinical performance by a prenatal cfDNA screen that incorporates fetal fraction (FF) amplification.

METHODS

The study cohort consisted of patients who received Prequel (Myriad Genetics, Inc.), a prenatal cfDNA screening that incorporates FF amplification, and met additional eligibility criteria. Pregnancy outcomes were obtained via a routine process for continuous quality improvement. Samples with diagnostic testing results were used to calculate positive predictive value (PPV).

RESULTS

379,428 patients met study eligibility criteria, 76 of whom were screen-positive for a de novo 22q11.2 microdeletion. 22 (29.7%) had diagnostic testing results available, and all 22 cases were confirmed as true positives, for a PPV of 100% (95% CI 84.6%-100%). This performance was based on cases that ranged broadly across FF (5.9%-41.1%, mean 23.0%), body mass index (22.3-44.8, mean 29.9), and gestational age at testing (10.0w-34.6w, median 12.7w). Ultrasound findings in screen-positive pregnancies were consistent with those known to be associated with 22q11.2DS.

CONCLUSION

22q11.2 microdeletion screening that incorporates FF amplification demonstrated high PPV across both general and high-risk population cohorts.

Test performance and clinical utility of expanded non-invasive prenatal test: Experience on 71,883 unselected routine cases from one single center

OBJECTIVE

The balance between benefits and risks of discordant outcomes makes the Genome-Wide Non-Invasive Prenatal Test (GW-NIPT) controversial. This study aims to evaluate performance and clinical utility in a wide cohort of unselected clinical cases from a single center when a standardized protocol is applied and integrated with a secondary algorithm for data interpretation.

METHOD

In 2 years, over 70,000 pregnant patients underwent GW-NIPT for fetal common trisomies, sex chromosome aneuploidies, rare autosomal aneuploidies, segmental abnormalities (CNVs ≥ 7 Mb) and microdeletions (CNVs < 7 Mb). All samples were uniformly processed with Veriseq NIPT Solution v2 and analyzed using all data metrics along with a home-made algorithm for sequencing data analysis. Results were retrospectively reviewed for clinical outcomes.

RESULTS

Among 71,883 eligible cases including twin pregnancies, 1011 (1.4%) received a positive result and 781 were confirmed by invasive prenatal diagnosis. Clinical sensitivity ranged from 99.65% for common trisomy (T21, T18, T13) to 83.33% for microdeletions, while specificity remained high (99.98%) for each class of fetal abnormalities detected.

CONCLUSIONS

Integrating a standardized protocol with an internal algorithm allowed discordant results to be reduced, yielding high accuracy. Observed reliability in detecting genome-wide chromosomal conditions reinforced the expanded NIPT utility in clinical practice.

Advancing fetal diagnosis and prognostication using comprehensive prenatal phenotyping and genetic testing

Prenatal diagnoses of congenital malformations have increased significantly in recent years with use of high-resolution prenatal imaging. Despite more precise radiological diagnoses, discussions with expectant parents remain challenging because congenital malformations are associated with a wide spectrum of outcomes. Comprehensive prenatal genetic testing has become an essential tool that improves the accuracy of prognostication. Testing strategies include chromosomal microarray, exome sequencing, and genome sequencing. The diagnostic yield varies depending on the specific malformations, severity of the abnormalities, and multi-organ involvement. The utility of prenatal genetic diagnosis includes increased diagnostic clarity for clinicians and families, informed pregnancy decision-making, neonatal care planning, and reproductive planning. Turnaround time for results of comprehensive genetic testing remains a barrier, especially for parents that are decision-making, although this has improved over time. Uncertainty inherent to many genetic testing results is a challenge. Appropriate genetic counseling is essential for parents to understand the diagnosis and prognosis and to make informed decisions. Recent research has investigated the yield of exome or genome sequencing in structurally normal fetuses, both with non-invasive screening methods and invasive diagnostic testing; the prenatal diagnostic community must evaluate and analyze the significant ethical considerations associated with this practice prior to generalizing its use. IMPACT: Reviews available genetic testing options during the prenatal period in detail. Discusses the impact of prenatal genetic testing on care using case-based examples. Consolidates the current literature on the yield of genetic testing for prenatal diagnosis of congenital malformations.

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.

Enlarged cavum septum pellucidum and small thymus as markers for 22q11.2 deletion syndrome

BACKGROUND

Enlarged cavum septum pellucidum (CSP) and hypoplastic thymus are proposed extra-cardiac fetal markers for 22q11.2 deletion syndrome. We sought to determine if they were part of the fetal phenotype of our cohort of fetuses with 22q11.2 deletion syndrome.

METHODS

Case-control study of fetuses evaluated from 2016 to 2022. The study group included fetuses with laboratory confirmation of 22q11.2 deletion syndrome. The control group included pregnancies with conotruncal cardiac anomalies with normal microarray as well as structurally normal fetuses with normal microarray. The CSP and thymus were routinely measured during anatomical ultrasound in all patients at their initial visit at 27.1 ± 4.7 weeks. The CSP and thymus measurements were classified as abnormal if they were >95% or <5% for gestational age, respectively. The groups were compared using analysis of variance or Kruskal-Wallis for continuous variables and Fisher's exact test for categorical variables. Logistic regression was performed, and a Receiver Operating Characteristic (ROC) curve was constructed.

RESULTS

We identified 47 fetuses with 22q11.2 deletion syndrome and compared them to 47 fetuses with conotruncal anomalies and normal microarray and 47 structurally normal fetuses with normal microarray. 51% (24/47) of fetuses with 22q11.2 deletion syndrome had an enlarged CSP compared to 6% (3/47) of fetuses with a conotruncal anomaly and normal microarray and none of the structurally normal fetuses (p < 0.001). Of the fetuses with 22q11.2 deletion syndrome, 83% (39/47) had a hypoplastic or absent thymus compared to 9% (4/47) of the fetuses with a conotruncal anomaly and normal microarray and none of the structurally normal fetuses (p < 0.001). 87% (41/47) of the fetuses with 22q11.2 deletion syndrome had conotruncal cardiac anomalies. Logistic regression revealed that both enlarged CSP and hypoplastic/absent thymus were associated with 22q11.2 deletion syndrome. The area under the ROC curve for the two markers was 0.94.

CONCLUSION

An enlarged CSP and hypoplastic/absent thymus appear to be part of the fetal phenotype of 22q11.2 deletion syndrome. These markers are associated with conotruncal anomalies in the setting of 22q11.2 deletion syndrome but not in normal controls or fetuses with conotruncal defects and normal microarrays.

Young adults with a 22q11.2 microdeletion and the cost of aging with complexity in a population-based context

PURPOSE

Information about the impact on the adult health care system is limited for complex rare pediatric diseases, despite their increasing collective prevalence that has paralleled advances in clinical care of children. Within a population-based health care context, we examined costs and multimorbidity in adults with an exemplar of contemporary genetic diagnostics.

METHODS

We estimated direct health care costs over an 18-year period for adults with molecularly confirmed 22q11.2 microdeletion (cases) and matched controls (total 60,459 person-years of data) by linking the case cohort to health administrative data for the Ontario population (∼15 million people). We used linear regression to compare the relative ratio (RR) of costs and to identify baseline predictors of higher costs.

RESULTS

Total adult (age ≥ 18) health care costs were significantly higher for cases compared with population-based (RR 8.5, 95% CI 6.5-11.1) controls, and involved all health care sectors. At study end, when median age was <30 years, case costs were comparable to population-based individuals aged 72 years, likelihood of being within the top 1st percentile of health care costs for the entire (any age) population was significantly greater for cases than controls (odds ratio [OR], for adults 17.90, 95% CI 7.43-43.14), and just 8 (2.19%) cases had a multimorbidity score of zero (vs 1483 (40.63%) controls). The 22q11.2 microdeletion was a significant predictor of higher overall health care costs after adjustment for baseline variables (RR 6.9, 95% CI 4.6-10.5).

CONCLUSION

The findings support the possible extension of integrative models of complex care used in pediatrics to adult medicine and the potential value of genetic diagnostics in adult clinical medicine.

Prenatal vs postnatal diagnosis of 22q11.2 deletion syndrome: cardiac and noncardiac outcomes through 1 year of age

BACKGROUND

The 22q11.2 deletion syndrome is the most common microdeletion syndrome and is frequently associated with congenital heart disease. Prenatal diagnosis of 22q11.2 deletion syndrome is increasingly offered. It is unknown whether there is a clinical benefit to prenatal detection as compared with postnatal diagnosis.

OBJECTIVE

This study aimed to determine differences in perinatal and infant outcomes between patients with prenatal and postnatal diagnosis of 22q11.2 deletion syndrome.

STUDY DESIGN

This was a retrospective cohort study across multiple international centers (30 sites, 4 continents) from 2006 to 2019. Participants were fetuses, neonates, or infants with a genetic diagnosis of 22q11.2 deletion syndrome by 1 year of age with or without congenital heart disease; those with prenatal diagnosis or suspicion (suggestive ultrasound findings and/or high-risk cell-free fetal DNA screen for 22q11.2 deletion syndrome with postnatal confirmation) were compared with those with postnatal diagnosis. Perinatal management, cardiac and noncardiac morbidity, and mortality by 1 year were assessed. Outcomes were adjusted for presence of critical congenital heart disease, gestational age at birth, and site.

RESULTS

A total of 625 fetuses, neonates, or infants with 22q11.2 deletion syndrome (53.4% male) were included: 259 fetuses were prenatally diagnosed (156 [60.2%] were live-born) and 122 neonates were prenatally suspected with postnatal confirmation, whereas 244 infants were postnatally diagnosed. In the live-born cohort (n=522), 1-year mortality was 5.9%, which did not differ between groups but differed by the presence of critical congenital heart disease (hazard ratio, 4.18; 95% confidence interval, 1.56-11.18; P<.001) and gestational age at birth (hazard ratio, 0.78 per week; 95% confidence interval, 0.69-0.89; P<.001). Adjusting for critical congenital heart disease and gestational age at birth, the prenatal cohort was less likely to deliver at a local community hospital (5.1% vs 38.2%; odds ratio, 0.11; 95% confidence interval, 0.06-0.23; P<.001), experience neonatal cardiac decompensation (1.3% vs 5.0%; odds ratio, 0.11; 95% confidence interval, 0.03-0.49; P=.004), or have failure to thrive by 1 year (43.4% vs 50.3%; odds ratio, 0.58; 95% confidence interval, 0.36-0.91; P=.019).

CONCLUSION

Prenatal detection of 22q11.2 deletion syndrome was associated with improved delivery management and less cardiac and noncardiac morbidity, but not mortality, compared with postnatal detection.

Prospective prenatal cell-free DNA screening for genetic conditions of heterogenous etiologies

Prenatal cell-free DNA (cfDNA) screening uses extracellular fetal DNA circulating in the peripheral blood of pregnant women to detect prevalent fetal chromosomal anomalies. However, numerous severe conditions with underlying single-gene defects are not included in current prenatal cfDNA screening. In this prospective, multicenter and observational study, pregnant women at elevated risk for fetal genetic conditions were enrolled for a cfDNA screening test based on coordinative allele-aware target enrichment sequencing. This test encompasses the following three of the most frequent pathogenic genetic variations: aneuploidies, microdeletions and monogenic variants. The cfDNA screening results were compared to invasive prenatal or postnatal diagnostic test results for 1,090 qualified participants. The comprehensive cfDNA screening detected a genetic alteration in 135 pregnancies with 98.5% sensitivity and 99.3% specificity relative to standard diagnostics. Of 876 fetuses with suspected structural anomalies on ultrasound examination, comprehensive cfDNA screening identified 55 (56.1%) aneuploidies, 6 (6.1%) microdeletions and 37 (37.8%) single-gene pathogenic variants. The inclusion of targeted monogenic conditions alongside chromosomal aberrations led to a 60.7% increase (from 61 to 98) in the detection rate. Overall, these data provide preliminary evidence that a comprehensive cfDNA screening test can accurately identify fetal pathogenic variants at both the chromosome and single-gene levels in high-risk pregnancies through a noninvasive approach, which has the potential to improve prenatal evaluation of fetal risks for severe genetic conditions arising from heterogenous molecular etiologies. ClinicalTrials.gov registration: ChiCTR2100045739 .

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.

Impact of high-risk prenatal screening results for 22q11.2 deletion syndrome on obstetric and neonatal management: Secondary analysis from the SMART study

OBJECTIVE

One goal of prenatal genetic screening is to optimize perinatal care and improve infant outcomes. We sought to determine whether high-risk cfDNA screening for 22q11.2 deletion syndrome (22q11.2DS) affected prenatal or neonatal management.

METHODS

This was a secondary analysis from the SMART study. Patients with high-risk cfDNA results for 22q11.2DS were compared with the low-risk cohort for pregnancy characteristics and obstetrical management. To assess differences in neonatal care, we compared high-risk neonates without prenatal genetic confirmation with a 1:1 matched low-risk cohort.

RESULTS

Of 18,020 eligible participants enrolled between 2015 and 2019, 38 (0.21%) were high-risk and 17,982 (99.79%) were low-risk for 22q11.2DS by cfDNA screening. High-risk participants had more prenatal diagnostic testing (55.3%; 21/38 vs. 2.0%; 352/17,982, p < 0.001) and fetal echocardiography (76.9%; 10/13 vs. 19.6%; 10/51, p < 0.001). High-risk newborns without prenatal diagnostic testing had higher rates of neonatal genetic testing (46.2%; 6/13 vs. 0%; 0/51, P < 0.001), echocardiography (30.8%; 4/13 vs. 4.0%; 2/50, p = 0.013), evaluation of calcium levels (46.2%; 6/13 vs. 4.1%; 2/49, P < 0.001) and lymphocyte count (53.8%; 7/13 vs. 15.7%; 8/51, p = 0.008).

CONCLUSIONS

High-risk screening results for 22q11.2DS were associated with higher rates of prenatal and neonatal diagnostic genetic testing and other 22q11.2DS-specific evaluations. However, these interventions were not universally performed, and >50% of high-risk infants were discharged without genetic testing, representing possible missed opportunities to improve outcomes for affected individuals.

A Diagnosis of Maternal 22q Duplication and Mosaic Deletion following Prenatal Cell-Free DNA Screening

Concurrent microduplication and microdeletion of the chromosome 22q11.2 region are a rarely reported phenomenon. We describe a case of germline 22q11.21 microduplication syndrome with concurrent mosaic 22q11.2 deletion in a pregnant patient, identified by chromosomal microarray and FISH after noninvasive prenatal genetic screening (cfDNA) results discordant with family history. The patient was referred to maternal-fetal medicine (MFM) at 14 weeks' gestation secondary to an SNP-based cfDNA result of a suspected maternal 22q11.2 deletion and a fetal risk of 1 in 2 for 22q11.2 deletion syndrome. The patient reported a similar cfDNA result in a previous pregnancy; however postnatal chromosomal microarray on that child identified an atypical 22q11.21 microduplication. We report the maternal chromosomal microarray findings of a germline 726 kb 22q11.21 duplication and a mosaic 1.33 Mb 22q11.2 deletion and highlight the copy number variant data generated by cfDNA in this unique case. This family adds to the limited literature of concurrent 22q11.2 microduplication and microdeletion carriers.

Perinatal Diagnosis and Management of a Case with Interrupted Aortic Arch, Pulmonary Valve Dysplasia and 22q11.2 Deletion: A Case Report

The 22q11.2 deletion syndrome (22q11.2DS) is the most common chromosomal microdeletion disorder caused by hemizygous microdeletion of the long arm of chromosome 22. It is now known to have a heterogenous presentation that includes multiple additional congenital anomalies and later-onset conditions, such as gastrointestinal and renal abnormalities, autoimmune disease, variable cognitive delays, behavioral phenotypes and psychiatric illness. The purpose of our paper is to present the case of a fetus diagnosed with a complex association of cardiac anomalies: interrupted aortic arch type B, large malalignment-type ventricular septal defect, pulmonary valve dysplasia, and aberrant right subclavian artery for whom the result of genetic testing revealed 22q11.2 deletion. The pregnancy was regularly followed until delivery which took place in Germany so that neonatal cardiac surgery could be performed in an experienced center for cardiac malformations. The distinctivness of our report resides in the fact that it offers a complete image of a case of 22q11.2 deletion syndrome starting from the prenatal diagnosis (and emphasizing on the most relevant sonographic features) and, with parents not opting for termination of pregnancy, ending with the newborn surviving major cardiac surgery, offering thus the possibility to bring into focus postnatal outcome and future expectations in similar cases.

Prenatal Screening for Microdeletions and Rare Autosomal Aneuploidies

Noninvasive prenatal screening with cell-free DNA is now considered a first-line screening for common aneuploidies. Advancements in existing laboratory techniques now allow to interrogate the entirety of the fetal genome, and many commercial laboratories have expanded their screening panels to include screening for rare autosomal aneuploidies and copy number variants. Here, we review the currently available data on the performance of fetal cell-free DNA to detect rare autosomal aneuploidies and copy number variants that are associated with clinically significant microdeletion and microduplication syndromes and the current position of medical societies on routine screening for these syndromes.

Obstetrical, perinatal, and genetic outcomes associated with nonreportable prenatal cell-free DNA screening results

BACKGROUND

The clinical implications of nonreportable cell-free DNA screening results are uncertain, but such results may indicate poor placental implantation in some cases and be associated with adverse obstetrical and perinatal outcomes.

OBJECTIVE

This study aimed to assess the outcomes of pregnancies with nonreportable cell-free DNA screening in a cohort of patients with complete genetic and obstetrical outcomes.

STUDY DESIGN

This was a prespecified secondary analysis of a multicenter prospective observational study of prenatal cell-free DNA screening for fetal aneuploidy and 22q11.2 deletion syndrome. Participants who underwent cell-free DNA screening from April 2015 through January 2019 were offered participation. Obstetrical outcomes and neonatal genetic testing results were collected from 21 primary-care and referral centers in the United States, Europe, and Australia. The primary outcome was risk for adverse obstetrical and perinatal outcomes (aneuploidy, preterm birth at <28, <34, and <37 weeks' gestation, preeclampsia, small for gestational age or birthweight <10th percentile for gestational week, and a composite outcome that included preterm birth at <37 weeks, preeclampsia, small for gestational age, and stillbirth at >20 weeks) after nonreportable cell-free DNA screening because of low fetal fraction or other causes. Multivariable analyses were performed, adjusting for variables known to be associated with obstetrical and perinatal outcomes, nonreportable results, or fetal fraction.

RESULTS

In total, 25,199 pregnant individuals were screened, and 20,194 were enrolled. Genetic confirmation was missing in 1165 (5.8%), 1085 (5.4%) were lost to follow-up, and 93 (0.5%) withdrew; the final study cohort included 17,851 (88.4%) participants who had cell-free DNA, fetal or newborn genetic confirmatory testing, and obstetrical and perinatal outcomes collected. Results were nonreportable in 602 (3.4%) participants. A sample was redrawn and testing attempted again in 427; in 112 (26.2%) participants, results were again nonreportable. Nonreportable results were associated with higher body mass index, chronic hypertension, later gestational age, lower fetal fraction, and Black race. Trisomy 13, 18, or 21 was confirmed in 1.6% with nonreportable tests vs 0.7% with reported results (P=.013). Rates of preterm birth at <28, 34, and 37 weeks, preeclampsia, and the composite outcome were higher among participants with nonreportable results, and further increased among those with a second nonreportable test, whereas the rate of small for gestational age infants was not increased. After adjustment for confounders, the adjusted odds ratios were 2.2 (95% confidence interval, 1.1-4.4) and 2.6 (95% confidence interval, 0.6-10.8) for aneuploidy, and 1.5 (95% confidence interval, 1.2-1.8) and 2.1 (95% confidence interval, 1.4-3.2) for the composite outcome after a first and second nonreportable test, respectively. Of the patients with nonreportable tests, 94.9% had a live birth, as opposed to 98.8% of those with reported test results (adjusted odds ratio for livebirth, 0.20 [95% confidence interval, 0.13-0.30]).

CONCLUSION

Patients with nonreportable cell-free DNA results are at increased risk for a number of adverse outcomes, including aneuploidy, preeclampsia, and preterm birth. They should be offered diagnostic genetic testing, and clinicians should be aware of the increased risk of pregnancy complications.

Chorionic Villous Testing Versus Amniocentesis After Abnormal Noninvasive Prenatal Testing

In the setting of a normal first-trimester ultrasound, an amniocentesis may be a better option than chorionic villous sampling for invasive diagnostic testing after a cell-free DNA high risk for trisomy 13, given the high rates of confined placental mosaicism. In unaffected fetuses, other evaluations should be considered depending on the cell-free DNA results, including maternal karyotyping for monosomy X, uniparental disomy testing for chromosomes with imprinted genes, serial growth scans for trisomy 16, and a workup for maternal malignancy for multiple aneuploidies or autosomal monosomy.

Overview of Noninvasive Prenatal Testing (NIPT) for the Detection of Fetal Chromosome Abnormalities; Differences in Laboratory Methods and Scope of Testing

Although nearly all noninvasive prenatal testing is currently based on analyzing circulating maternal cell-free DNA, the technical methods usedvary considerably. We review the different methods. Based on validation trials and clinical experience, there are mostly relatively small differences in screening performance for trisomies 21, 18, and 13 in singleton pregnancies. Recent reports show low no-call rates for all methods, diminishing its importance when choosing a laboratory. However, method can be an important consideration for twin pregnancies, screening for sex chromosome abnormalities, microdeletion syndromes, triploidy, molar pregnancies, rare autosomal trisomies, and segmental imbalances, and detecting maternal chromosome abnormalities.

Noninvasive Prenatal Testing Using Circulating DNA and RNA: Advances, Challenges, and Possibilities

Prenatal screening using sequencing of circulating cell-free DNA has transformed obstetric care over the past decade and significantly reduced the number of invasive diagnostic procedures like amniocentesis for genetic disorders. Nonetheless, emergency care remains the only option for complications like preeclampsia and preterm birth, two of the most prevalent obstetrical syndromes. Advances in noninvasive prenatal testing expand the scope of precision medicine in obstetric care. In this review, we discuss advances, challenges, and possibilities toward the goal of providing proactive, personalized prenatal care. The highlighted advances focus mainly on cell-free nucleic acids; however, we also review research that uses signals from metabolomics, proteomics, intact cells, and the microbiome. We discuss ethical challenges in providing care. Finally, we look to future possibilities, including redefining disease taxonomy and moving from biomarker correlation to biological causation.

Clinical Course and Outcome of Prenatally Detected 22q11.2 Deletion Syndrome-A Retrospective Analysis

The 22q11.2 deletion syndrome (22q11.2 DS) is known as the most common microdeletion syndrome. Due to its variable clinical phenotype, prenatal diagnosis can be challenging. The aim of this retrospective study was to evaluate the clinical course and pregnancy outcome of cases with prenatally diagnosed 22q11.2 deletion syndrome (DS) as well as to evaluate the role of prenatal magnetic resonance imaging (MRI) and postmortem examination. In total, 21 cases who underwent prenatal ultrasound examination and pregnancy care at the Department of Obstetrics and Gynecology at the Medical University of Vienna between 2012 and 2022 were included. The majority of the cases were genetically diagnosed using fluorescent in situ hybridization (FISH). The median gestational age (GA) at genetic diagnosis was 23.0 weeks (IQR 21.4-24.8 weeks). CHDs were detected in all fetuses and the most common extracardiac manifestation was thymus hypo/aplasia followed by genitourinary anomalies. Prenatal magnetic resonance imaging (MRI) revealed additional diagnostic information in three of ten cases. Overall, 14 patients opted for drug-induced TOP, of which 9 cases had a feticide prior to the induction of labor. The majority of craniofacial malformations were only detected by autopsy. In conclusion, the majority of cases prenatally diagnosed with 22q11.2 DS had an absent or hypoplastic thymus noted antenatally in addition to the detected CHD, and almost half of the cases had another extracardiac malformation of predominantly genitourinary origin. Furthermore, prenatal MRIs confirmed previously detected malformations, but only provided additional diagnostic information in three out of ten cases, whereas postmortem examination diagnosed most of the craniofacial anomalies and should always be conducted, serving as an important quality indicator for prenatal imaging.

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?

Chromosome 22q11.2 Deletion Syndrome: A Comprehensive Review of Molecular Genetics in the Context of Multidisciplinary Clinical Approach

The 22q11.2 deletion syndrome is a multisystemic disorder characterized by a marked variability of phenotypic features, making the diagnosis challenging for clinicians. The wide spectrum of clinical manifestations includes congenital heart defects-most frequently conotruncal cardiac anomalies-thymic hypoplasia and predominating cellular immune deficiency, laryngeal developmental defects, midline anomalies with cleft palate and velar insufficiency, structural airway defects, facial dysmorphism, parathyroid and thyroid gland hormonal dysfunctions, speech delay, developmental delay, and neurocognitive and psychiatric disorders. Significant progress has been made in understanding the complex molecular genetic etiology of 22q11.2 deletion syndrome underpinning the heterogeneity of clinical manifestations. The deletion is caused by chromosomal rearrangements in meiosis and is mediated by non-allelic homologous recombination events between low copy repeats or segmental duplications in the 22q11.2 region. A range of genetic modifiers and environmental factors, as well as the impact of hemizygosity on the remaining allele, contribute to the intricate genotype-phenotype relationships. This comprehensive review has been aimed at highlighting the molecular genetic background of 22q11.2 deletion syndrome in correlation with a clinical multidisciplinary approach.

Chromosome 22q11.2 Deletion (DiGeorge Syndrome): Immunologic Features, Diagnosis, and Management

PURPOSE OF REVIEW

This review focuses on immunologic findings, relationships among immunologic findings and associated conditions of autoimmunity and atopy, and management of immunologic disease in chromosome 22q11.2 deletion syndrome (22q11.2DS, historically known as DiGeorge syndrome).

RECENT FINDINGS

The implementation of assessment of T cell receptor excision circles (TRECs) in newborn screening has led to increased detection of 22q11.2 deletion syndrome. While not yet applied in clinical practice, cell-free DNA screening for 22q11.2DS also has the potential to improve early detection, which may benefit prompt evaluation and management. Multiple studies have further elucidated phenotypic features and potential biomarkers associated with immunologic outcomes, including the development of autoimmune disease and atopy. The clinical presentation of 22q11.2DS is highly variable particularly with respect to immunologic manifestations. Time to recovery of immune system abnormalities is not well-defined in current literature. An understanding of the underlying causes of immunologic changes found in 22q11.2DS, and the progression and evolution of immunologic changes over the lifespan have expanded over time and with improved survival. An included case highlights the variability of presentation and potential severity of T cell lymphopenia in partial DiGeorge syndrome and demonstrates successful spontaneous immune reconstitution in partial DiGeorge syndrome despite initial severe T cell lymphopenia.

Positive cfDNA screening results for 22q11.2 deletion syndrome—Clinical and laboratory considerations

Introduction: Non-invasive prenatal screening (NIPS) via cell-free DNA (cfDNA) screens for fetal chromosome disorders using maternal plasma, including 22q11.2 deletion syndrome (22q11.2DS). While it is the commonest microdeletion syndrome and has potential implications for perinatal management, prenatal screening for 22q11.2DS carries some inherent technical, biological, and counseling challenges, including varying deletion sizes/locations, maternal 22q11.2 deletions, confirmatory test choice, and variable phenotype.

Materials and methods: This study addresses these considerations utilizing a retrospective cohort of 307 samples with screen-positive 22q11.2 NIPS results on a massively parallel sequencing (MPS) platform.

Results: Approximately half of the cases reported ultrasound findings at some point during pregnancy. In 63.2% of cases with diagnostic testing, observed positive predictive values were 90.7%–99.4%. cfDNA identified deletions ranging from &lt;1 Mb to 3.55 Mb, with significant differences in confirmed fetal versus maternal deletion sizes; estimated cfDNA deletion size was highly concordant with microarray findings. Mosaicism ratio proved useful in predicting the origin of a deletion (fetal versus maternal). Prediction of deletion size, location, and origin may help guide confirmatory testing.

Discussion: The data shows that MPS-based NIPS can screen for 22q11.2DS with a high PPV, and that collaboration between the laboratory and clinicians allows consideration of additional metrics that may guide diagnostic testing and subsequent management.

Resistance to Change

Advances in medical technology do not follow a smooth process and are highly variable. Implementation can occasionally be rapid, but often faces varying degrees of resistance resulting at the very least in delayed implementation. Using qualitative comparative analysis, we have evaluated numerous technological advances from the perspective of how they were introduced, implemented, and opposed. Resistance varies from benign - often happening because of inertia or lack of resources to more active forms, including outright opposition using both appropriate and inappropriate methods to resist/delay changes in care. Today, even public health has become politicized, having nothing to do with the underlying science, but having catastrophic results. Two other corroding influences are marketing pressure from the private sector and vested interests in favor of one outcome or another. This also applies to governmental agencies. There are a number of ways in which papers have been buried including putting the thumb on the scale where reviewers can sabotage new ideas. Unless we learn to harness new technologies earlier in their life course and understand how to maneuver around the pillars of obstruction to their implementation, we will not be able to provide medical care at the forefront of technological capabilities.

Noninvasive prenatal screening (NIPS) for fetal chromosome abnormalities in a general-risk population: An evidence-based clinical guideline of the American College of Medical Genetics and Genomics (ACMG)

PURPOSE

This workgroup aimed to develop an evidence-based clinical practice guideline for the use of noninvasive prenatal screening (NIPS) for pregnant individuals at general risk for fetal trisomy 21, trisomy 18, or trisomy 13 and to evaluate the utility of NIPS for other chromosomal disorders.

METHODS

The NIPS Evidence-Based Guideline Work Group (n = 7) relied on the results from the recent American College of Medical Genetics and Genomics (ACMG) systematic review to form the evidentiary basis of this guideline. Workgroup members used the Grading of Recommendations Assessment, Development, and Evaluation Evidence to Decision framework to draft recommendations. The guideline underwent extensive internal and external peer review with a public comment period before approval by the ACMG Board of Directors.

RESULTS

Evidence consistently demonstrated improved accuracy of NIPS compared with traditional screening methods for trisomies 21, 18, and 13 in singleton and twin gestations. Identification of rare autosomal trisomies and other microdeletion syndromes with NIPS is an emerging area of interest.

CONCLUSION

ACMG strongly recommends NIPS over traditional screening methods for all pregnant patients with singleton and twin gestations for fetal trisomies 21, 18, and 13 and strongly recommends NIPS be offered to patients to screen for fetal sex chromosome aneuploidy.

The accuracy of cell-free DNA screening for fetal segmental copy number variants: A systematic review and meta-analysis

BACKGROUND

The performance of cell-free DNA (cfDNA) screening for microscopic copy number variants (CNVs) is unclear.

OBJECTIVES

This was a systematic review and meta-analysis to investigate the sensitivity, specificity and positive predictive value (PPV) of cfDNA screening for CNVs.

SEARCH STRATEGY

Articles published in EMBASE, PubMed or Web of Science before November 2022 were screened for inclusion. This protocol was registered with PROSPERO (23 March 2021, CRD42021250849) prior to initiation.

SELECTION CRITERIA

Articles published in English, detailing diagnostic outcomes for at least 10 high-risk CNV results with cfDNA were considered for inclusion.

DATA COLLECTION AND ANALYSIS

The PPV was calculated and pooled with random-effects models for double-arcsine transformed proportions, using cases with diagnostic confirmation. Overall sensitivity, specificity and a summary receiver-operating characteristics (ROC) curve were calculated using bivariate models. The risk of bias was assessed using QUADAS-2.

MAIN RESULTS

In all, 63 articles were included in the final analysis, detailing 1 591 459 cfDNA results. The pooled PPV was 37.5% (95% confidence interval [CI] 30.6-44.8), with substantial statistical heterogeneity (I²  = 93.9%). Bivariate meta-analysis estimated sensitivity and specificity to be 77.4% (95% CI 65.7-86.0) and 99.4% (95% CI 98.0-99.8), respectively, with an area under the summary ROC curve of 0.947 (95% CI 0.776-0.984).

CONCLUSIONS

Approximately one-third of women who screen high-risk for CNVs with cfDNA will have an affected fetus. This value is of importance for screening counselling.

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.

Positive predictive value of a single nucleotide polymorphism (SNP)-based NIPT for aneuploidy in twins: Experience from clinical practice

OBJECTIVE

Twins account for approximately 1 in 30 live births in the United States. However, there are limited clinical experience studies published in noninvasive prenatal testing (NIPT) for detecting aneuploidies in twins. This study reports the performance of an SNP-based NIPT in the largest cohort with known outcomes for high-risk aneuploidy results.

METHOD

This is a retrospective analysis of 18,984 results from commercial single-nucleotide polymorphism (SNP)-based NIPT tests performed in twins between October 2, 2017 and December 31, 2019. Follow-up for all 211 high-risk cases was solicited.

RESULTS

Follow-up outcomes were obtained in 105 cases. Positive predictive values (PPVs) for high-risk results were 88.7% (63/71, 95% Confidence Interval [CI]: 79.0%-95.0%) for trisomy 21% and 72.7% (8/11, 95% CI: 39.0%-94.0%) for trisomy 18. The results were stratified into monozygotic (MZ) and dizygotic (DZ). The PPVs in MZ were 100% for both trisomy 21 (4/4, 95% CI: 40%-100%) and trisomy 18 (1/1, 95% CI: 2.5%-100%). No trisomy 13 cases were detected in the MZ group. The PPVs in DZ were 88.1% (59/67, 95% CI: 77.8%-94.7%), 70.0% (7/10, 95% CI: 34.8%-93.3%), and 66.7% (2/3, 95% CI: 9.4%-99.2%) for trisomy 21, trisomy 18, and trisomy 13, respectively.

CONCLUSION

The performance of SNP-based NIPT in this large twin cohort was comparable to previously reported twin NIPT studies. SNP-based NIPT allows for zygosity-based PPV assessment.

Reproductive Outcomes in Adults with 22q11.2 Deletion Syndrome

The 22q11.2 microdeletion and its associated conditions could affect reproductive outcomes but there is limited information on this important area. We investigated reproductive outcomes in a sample of 368 adults with typical 22q11.2 deletions (median age 32.8, range 17.9-76.3 years; 195 females), and without moderate-severe intellectual disability, who were followed prospectively. We examined all reproductive outcomes and possible effects of diagnosis as a transmitting parent on these outcomes. We used logistic regression to investigate factors relevant to reproductive fitness (liveborn offspring). There were 63 (17.1%) individuals with 157 pregnancy outcomes, 94 (60.3%) of which involved live births. Amongst the remainder involving a form of loss, were seven (5.77%) stillbirths, significantly greater than population norms (p < 0.0001). For 35 (55.6%) individuals, diagnosis of 22q11.2 deletion syndrome (22q11.2DS) followed diagnosis of an offspring, with disproportionately fewer individuals had major congenital heart disease (CHD) in that transmitting parent subgroup. The regression model indicated that major CHD, in addition to previously identified factors, was a significant independent predictor of reduced reproductive fitness. There was evidence of persisting diagnostic delay and limited prenatal genetic testing. The findings indicate that pregnancy loss is an important health issue for adults with 22q11.2DS. CHD and/or its absence is a factor to consider in reproductive outcome research. Further studies are warranted to better appreciate factors that may contribute to reproductive outcomes, including technological advances. The results suggest the need for ongoing efforts to provide optimal education and supports to individuals with 22q11.2DS, and their clinicians, around reproductive issues and early diagnosis.