Molecular autopsy for fetal structural anomaly: diagnostic and clinical utility of multidisciplinary team approach.

OBJECTIVE: In the West Midlands regional genetics service, cases of perinatal death with a possible genetic diagnosis are evaluated by the perinatal pathology genetic multidisciplinary team (MDT). The MDT assesses autopsy findings and suggests appropriate genomic assessment. The objective of this retrospective service evaluation was to determine the clinical utility of the MDT in assessing perinatal deaths associated with structural anomaly. This is the first evaluation since the introduction of whole-genome and whole-exome sequencing in routine clinical care. METHODS: This was a retrospective service evaluation including all cases of perinatal death with an associated structural anomaly and suspected genetic etiology that underwent perinatal MDT assessment between January and December 2021. All cases received a full or partial postmortem examination and at least a chromosomal microarray analysis. Demographic characteristics, phenotype, genotype, MDT recommendations, diagnoses, outcomes and impact of postmortem analysis and genetic testing data were collected from patient case notes. RESULTS: Overall, 123 cases were discussed at the MDT meetings in 2021. Genetic evaluation was recommended in 84 cases and accepted in 64 cases. A range of genetic tests were requested according to indication and availability. Thirty diagnoses were made in 29 cases from 26 unrelated families. The diagnostic yield was 24% (29/123) in all cases or 45% (29/64) in cases with a suspected genetic diagnosis who underwent genetic testing. Postmortem examination provided clinically actionable phenotypic data in 79% of cases. A genetic diagnosis enabled accurate recurrence risk counseling and provision of appropriate follow-up, including prenatal testing and preimplantation diagnosis for patients with inherited conditions. CONCLUSIONS: Genomic testing was a clinically useful addition to (but not a substitute for) postmortem examination in cases of perinatal death associated with structural anomaly. The MDT approach helped assess cases and plan appropriate follow-up. Expedited whole-genome sequencing or panel-agnostic analysis were most appropriate for heterogeneous presentations. This broad approach can also expand knowledge of prenatal phenotypes and detect novel disease genes, and should be a priority in future research. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

The First Fetal Case of Shwachman-Diamond Syndrome Mimicking Vascular Growth Restriction.

Shwachman-Diamond Syndrome (SDS) is a rare autosomal recessive genetic condition with 90% of cases associated with biallelic pathogenic variants in the Shwachman-Bodian-Diamond Syndrome (SBDS) gene on chromosome 7q.11.21. SDS belongs to ribosomopathies since SBDS gene encodes a protein involved in ribosomal maturation. Its phenotypic postnatal hallmark features include growth delay, bone marrow failure, exocrine pancreatic insufficiency, and skeletal abnormalities. We report a first fetal case of Shwachman-Diamond syndrome and extend its phenotype before birth. The clinical features mimicked vascular growth restriction with FGR and shortened long bones, associated with abnormal Doppler indices. Non-restricted fetal autopsy after termination of pregnancy allowed deep phenotyping disclosing the features of fetal skeletal dysplasia. Post-fetopathological trio exome sequencing identified biallelic pathogenic variants in the SBDS gene. Genotype-phenotype correlations confirmed the diagnosis and enabled an adequate genetic counseling of the parents. Our case is another example of the positive impact of fetal autopsy coupled with post-fetopathological genomic studies, even in the cases that were hitherto classified as maternal or fetal vascular malperfusion.

Potentially Missed Diagnoses in Prenatal Versus Postnatal Exome Sequencing in the Lack of Informative Phenotype: Lessons Learned From a Postnatal Cohort.

OBJECTIVE: To investigate how many novel pathogenic (P) and likely pathogenic (LP) nonprotein-truncating or noncanonical splicing variants would be classified as variants of unknown significance (VUS) if they were detected in fetuses without abnormalities. METHODS: The study included 156 patients with neurodevelopmental disorders diagnosed through postnatal exome sequencing. Causative P/LP nonprotein-truncating and noncanonical splicing variants were retrospectively reclassified in cases without specific prenatal manifestations, disregarding postnatal symptoms. RESULTS: Of the 156 patients, 72 had a nontruncating or noncanonical splicing variant. Six patients were excluded for having more than one possible causative variant. Twelve patients had prenatal malformations known to be associated with the diagnosed disorder; therefore, variant interpretation remained unchanged. In 33 of the 54 remaining cases, the variant had been previously reported as P/LP. Reclassification of the other 21 LP/P variants revealed that 16 would have been classified as VUS if detected prenatally. CONCLUSION: In our cohort, ∼24% (16/66) of causative nonprotein-truncating/noncanonical splicing variants would have been classified as VUS if sequencing had been conducted during pregnancy. The potential for false-negative results, stemming from limitations in the phenotypic information available prenatally, should be discussed with prospective parents. The criteria for classifying and reporting variants in the prenatal setting may require adjustment.

Diagnostic yield from prenatal exome sequencing for non-immune hydrops fetalis: A systematic review and meta-analysis.

Non-immune hydrops fetalis (NIHF) has multiple genetic etiologies diagnosable by exome sequencing (ES). We evaluated the yield of prenatal ES for NIHF, and the contribution of additional clinical findings and history. Systematic review was performed with PROSPERO tag 232951 using CINAHL, PubMed, and Ovid MEDLINE from January 1, 2000 through December 1, 2021. Selected studies performed ES to augment standard prenatal diagnostic approaches. Cases meeting a strict NIHF phenotype were tabulated with structured data imputed from papers or requested from authors. Genetic variants and diagnostic outcomes were harmonized across studies using current ACMG and ClinGen variant classification guidelines. Thirty-one studies reporting 445 NIHF cases had a 37% (95% CI: 32%-41%) diagnostic rate. There was no significant difference between isolated NIHF and NIHF with fetal malformations or between recurrent and simplex cases. Diagnostic rate was higher for consanguineous than non-consanguineous cases. Disease categories included RASopathies (24%), neuromuscular (21%), metabolic (17%), lymphatic (13%), other syndromes (9%), cardiovascular (5%), hematologic (2%), skeletal (2%), and other categories (7%). Inheritance patterns included recessive (55%), dominant (41%), and X-linked (4%). ES should be considered in the diagnostic workup of NIHF with and without associated ultrasound findings regardless of history of recurrence or consanguinity.

An incidental finding in prenatal exome sequencing-A case study and review of the clinical and ethical considerations.

The introduction of genomic testing into prenatal care has come at a rapid pace and has been met with significant clinical and ethical challenges, specifically when dealing with incidental findings. We present the case of a couple in their first pregnancy who were referred to our institution with isolated fetal cataracts on morphology scan. After an unremarkable infectious disease workup and microarray on an amniocentesis sample, the couple opted for fetal whole-exome sequencing to investigate the cataracts further. This investigation did not find any cause for the cataracts but yielded an incidental finding of a de novo pathogenic variant in the SCN1A gene unrelated to the cataracts. Pathogenic variants in the SCN1A gene are strongly associated with severe myoclonic epilepsy of infancy, or Dravet syndrome. After extensive genetic counseling, the couple decided to terminate the pregnancy at 28 weeks' gestation based on this finding. This case highlights some of the important clinical and ethical considerations in prenatal genetic diagnosis, particularly in the group of patients in which there is no phenotypic evidence in-utero of the incidental finding. The case demonstrates the value of frameworks and guidelines to guide management decisions for both clinicians and patients.

Prenatal exome sequencing analysis in fetuses with central nervous system anomalies.

OBJECTIVE: To evaluate the utility of prenatal exome sequencing (pES) in fetuses with central nervous system (CNS) abnormalities. METHODS: This was a retrospective cohort study of fetuses identified to have CNS abnormality on prenatal ultrasound and/or magnetic resonance imaging. All fetuses were first analyzed by chromosomal microarray analysis (CMA). Fetuses with a confirmed aneuploidy or causal pathogenic copy-number variant (CNV) on CMA did not undergo pES analysis and were excluded, while those with a negative CMA result were offered pES testing. RESULTS: Of the 167 pregnancies included in the study, 42 (25.1%) were identified to have a pathogenic or likely pathogenic (P/LP) variant. The diagnostic rate was significantly higher in fetuses with a non-isolated CNS abnormality than in those with a single CNS abnormality (35.7% (20/56) vs 14.5% (8/55); P = 0.010). Moreover, when a fetus had three or more CNS abnormalities, the positive diagnostic rate increased to 42.9%. A total of 25/42 (59.5%) cases had de-novo mutations, while, in the remaining cases, mutations were inherited and carried a significant risk of recurrence. Families whose fetus carried a P/LP mutation were more likely to choose advanced pregnancy termination than those with a variant of uncertain significance, secondary/incidental finding or negative pES result (83.3% (25/30) vs 41.3% (38/92); P < 0.001). CONCLUSION: pES improved the identification of genetic disorders in fetuses with CNS anomalies without a chromosomal abnormality or CNV identified on CMA, regardless of the number of CNS anomalies and presence of extracranial abnormality. We also demonstrated that pES findings can significantly impact parental decision-making. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Utility of trio-based prenatal exome sequencing incorporating splice-site and mitochondrial genome assessment in pregnancies with fetal ultrasound anomalies: prospective cohort study.

OBJECTIVE: To evaluate the utility of trio-based prenatal exome sequencing (pES), incorporating splice-site and mitochondrial genome assessment, in the prenatal diagnosis of fetuses with ultrasound anomalies and normal copy-number variant sequencing (CNV-seq) results. METHODS: This was a prospective study of 90 ongoing pregnancies with ultrasound anomalies that underwent trio-based pES after receiving normal CNV-seq results, from September 2020 to November 2021, in a single center in China. By using pES with a panel encompassing exome coding and splicing regions as well as mitochondrial genome for fetuses and parents, we identified the underlying genetic causes of fetal anomalies, incidental fetal findings and parental carrier status. Information on pregnancy outcome and the impact of pES findings on parental decision-making was collected. RESULTS: Of the 90 pregnancies included, 28 (31.1%) received a diagnostic result that could explain the fetal ultrasound anomalies. The highest diagnostic yield was noted for brain abnormalities (3/6 (50.0%)), followed by hydrops (4/9 (44.4%)) and skeletal abnormalities (13/34 (38.2%)). Collectively, 34 variants of 20 genes were detected in the 28 diagnosed cases, with 55.9% (19/34) occurring de novo. Variants of uncertain significance (VUS) associated with fetal phenotypes were detected in six (6.7%) fetuses. Interestingly, fetal (n = 4) and parental (n = 3) incidental findings (IFs) were detected in seven (7.8%) cases. These included two fetuses carrying a de-novo likely pathogenic (LP) variant of the CIC and FBXO11 genes, respectively, associated with neurodevelopmental disorders, and one fetus with a LP variant in a mitochondrial gene. The remaining fetus presented with unilateral renal dysplasia and was incidentally found to carry a pathogenic PKD1 gene variant resulting in adult-onset polycystic kidney, which was later confirmed to be inherited from the mother. In addition, parental heterozygous variants associated with autosomal recessive diseases were detected in three families, including one with additional fetal diagnostic findings. Diagnostic results or fetal IFs contributed to parental decision-making about termination of the pregnancy in 26 families (26/72 (36.1%)), while negative pES results or identification of VUS encouraged 40 families (40/72 (55.6%)) to continue their pregnancy, which ended in a live birth in all cases. CONCLUSION: Trio-based pES can provide additional genetic information for pregnancies with fetal ultrasound anomalies without a CNV-seq diagnosis. The incidental findings and parental carrier status reported by trio-based pES with splice-site and mitochondrial genome analysis extend its clinical application, but careful genetic counseling is warranted. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal exome sequencing in 65 fetuses with abnormality of the corpus callosum: contribution to further diagnostic delineation.

PURPOSE: Abnormality of the corpus callosum (AbnCC) is etiologically a heterogeneous condition and the prognosis in prenatally diagnosed cases is difficult to predict. The purpose of our research was to establish the diagnostic yield using chromosomal microarray (CMA) and exome sequencing (ES) in cases with prenatally diagnosed isolated (iAbnCC) and nonisolated AbnCC (niAbnCC). METHODS: CMA and prenatal trio ES (pES) were done on 65 fetuses with iAbnCC and niAbnCC. Only pathogenic gene variants known to be associated with AbnCC and/or intellectual disability were considered. RESULTS: pES results were available within a median of 21.5 days (9-53 days). A pathogenic single-nucleotide variant (SNV) was identified in 12 cases (18%) and a pathogenic CNV was identified in 3 cases (4.5%). Thus, the genetic etiology was determined in 23% of cases. In all diagnosed cases, the results provided sufficient information regarding the neurodevelopmental prognosis and helped the parents to make an informed decision regarding the outcome of the pregnancy. CONCLUSION: Our results show the significant diagnostic and prognostic contribution of CMA and pES in cases with prenatally diagnosed AbnCC. Further prospective cohort studies with long-term follow-up of the born children will be needed to provide accurate prenatal counseling after a negative pES result.

Attitudes toward uncertain results from prenatal exome sequencing: a national survey among healthcare professionals working in the prenatal setting.

Objective: The objective of this study was to investigate the attitudes of healthcare professionals (HPs) working in the prenatal setting toward uncertain results (UR) from prenatal exome sequencing (pES) in China. Methods: We conducted a national survey among HPs working in the prenatal setting. UR in our study include variants of uncertain significance (VUS), variants with variable penetrance/expressivity (VVPE), and secondary findings unrelated to the indication for testing (SFs). A total of 285 questionnaires that met the inclusion criteria were collected. Data were analyzed using IBM SPSS Statistics 26. Results: When performing the pre-test counseling, only 7.4% of HPs mentioned the possibility of VUS, 6.3% discussed the possibility of VVPE, and 7.4% introduced the SFs with parents with the option to not report these variants. In post-test counseling, 73.0-82.8% HPs discussed with the parents but did not make any recommendations for managing the pregnancy after reporting UR (73.0% for VUS, 82.8% for VVPE, 74.7% for SFs, respectively). Conclusion: Most parents did not have the option of opting out of reporting UR from pES in pre-test counseling. UR did not influence the pregnancy recommendation made by most HPs. Establishing national guidelines for reporting UR from pES and developing strategies to improve counseling skills may help HPs manage UR.

Prenatal identification of a pathogenic maternal FGFR1 variant in two consecutive pregnancies with fetal forebrain malformations.

OBJECTIVE: Holoprosencephaly (HPE) is the most common aberration of forebrain development, and it leads to a wide spectrum of developmental and craniofacial anomalies. HPE etiology is highly heterogeneous and includes both chromosomal abnormalities and single-gene defects. METHODS: Here, we report an FGFR1 heterozygous variant detected by prenatal exome sequencing and inherited from the asymptomatic mother, in association with recurrent neurological abnormalities in the HPE spectrum in two consecutive pregnancies. RESULTS: Individuals with germline pathogenic variants in FGFR1 (MIM: 136350) show extensive phenotypic variability, which ranges from asymptomatic carriers to hypogonadotropic hypogonadism, arhinencephaly, Kallmann's syndrome with associated features such as cleft lip and palate, skeletal anomalies, isolated HPE, and Hartsfield syndrome. CONCLUSION: The presented case supports the role of exome sequencing in prenatal diagnosis when fetal midline structural anomalies are suggestive of a genetic etiology, as early as the first trimester of gestation. The profound heterogeneity of FGFR1 allelic disorders needs to be considered when planning prenatal screening even in asymptomatic carriers.

Identification of a novel LMX1B nonsense variant associated with congenital talipes equinovarus by prenatal exome sequencing: A case report.

BACKGROUND: Congenital talipes equinovarus (CTEV) is a rotational foot deformity that affects muscles, bones, connective tissue, and vascular or neurological tissues. The etiology of CTEV is complex and unclear, involving genetic and environmental factors. Nail-patella syndrome is an autosomal dominant disorder caused by variants of the LIM homeobox transcription factor 1 beta gene (LMX1B, OMIM:602575). LMX1B plays a key role in the development of dorsal limb structures, the kidneys, and the eyes, and variants in this gene may manifest as hypoplastic or absent patella, dystrophic nails, and elbow and iliac horn dysplasia; glomerulopathy; and adult-onset glaucoma, respectively. This study aimed to identify pathogenic variants in a fetus with isolated talipes equinovarus diagnosed by ultrasound in the second trimester, whose father exhibited dysplastic nails and congenital absence of bilateral patella. METHODS: Prenatal whole-exome sequencing (WES) of the fetus and parents was performed to identify the genetic variant responsible for the fetal ultrasound abnormality, followed by validation using Sanger sequencing. RESULTS: A novel heterozygous nonsense variant in exon 6 of LMX1B (c.844C>T, p.Gln282*) was identified in the fetus and the affected father but was not detected in any unaffected family members. This nonsense variant resulted in a premature termination codon at position 282, which may be responsible for the clinical phenotype through the loss of function of the gene product. CONCLUSIONS: Our study indicating that a fetus carrying a novel nonsense variant of LMX1B (c.844C>T, p.Gln282*) can exhibit isolated talipes equinovarus, which expands the LMX1B genotypic spectrum and is advantageous for genetic counseling.

Delivery of a national prenatal exome sequencing service in England: a mixed methods study exploring healthcare professionals' views and experiences.

Introduction: In October 2020, rapid prenatal exome sequencing (pES) was introduced into routine National Health Service (NHS) care in England, requiring the coordination of care from specialist genetics, fetal medicine (FM) and laboratory services. This mixed methods study explored the experiences of professionals involved in delivering the pES service during the first 2 years of its delivery in the NHS. Methods: A survey (n = 159) and semi-structured interviews (n = 63) with healthcare professionals, including clinical geneticists, FM specialists, and clinical scientists (interviews only) were used to address: 1) Views on the pES service; 2) Capacity and resources involved in offering pES; 3) Awareness, knowledge, and educational needs; and 4) Ambitions and goals for the future. Results: Overall, professionals were positive about the pES service with 77% rating it as Good or Excellent. A number of benefits were reported, including the increased opportunity for receiving actionable results for parental decision-making, improving equity of access to genomic tests and fostering close relationships between FM and genetics departments. Nonetheless, there was evidence that the shift to offering pES in a clinical setting had brought some challenges, such as additional clinic time, administrative processes, perceived lack of autonomy in decision-making regarding pES eligibility and difficulty engaging with peripheral maternity units. Concerns were also raised about the lack of confidence and gaps in genomics knowledge amongst non-genetics professionals - especially midwives. However, the findings also highlighted value in both FM, obstetric and genetics professionals benefiting from further training with a focus on recognising and managing prenatally diagnosed genetic conditions. Conclusion: Healthcare professionals are enthusiastic about the benefits of pES, and through multi-collaborative working, have developed relationships that have contributed to effective communication across specialisms. Although limitations on resources and variation in knowledge about pES have impacted service delivery, professionals were hopeful that improvements to infrastructure and the upskilling of all professionals involved in the pathway would optimise the benefits of pES for both parents and professionals.

Prenatal CFAP53-related laterality defect: case report and review of the literature.

Laterality defects include morphological anomalies with impaired left-right asymmetry induction, such as dextrocardia, situs inversus abdominis, situs inversus totalis and situs ambiguus. The different arrangement of major organs is called heterotaxy. We describe for the first time a fetus with situs viscerum inversus and azygos continuation of the inferior vena cava, due to previously unreported variants in compound heterozygosity in the CFAP53 gene, whose product is implied in cilial motility. Prenatal trio exome sequencing was performed with turn-around time during the pregnancy. The fetuses with laterality defects are suitable candidates for prenatal exome sequencing due to the emerging high diagnostic rate of this group of morphological anomalies. A timely molecular diagnosis plays a fundamental role in genetic counseling, regarding couple decisions on the ongoing pregnancy, providing recurrence risks, and in predicting possible respiratory complications due to ciliary dyskinesia.

The role of a multidisciplinary team in managing variants of uncertain clinical significance in prenatal genetic diagnosis.

BACKGROUND: Although in general prenatal exome sequencing only reports (likely) pathogenic variants, in some cases a variant of uncertain significance (VUS) is disclosed. The aims of this retrospective study were to evaluate the types of VUS that have been reported to prospective parents, possible reclassification and to design a standard flow chart to determine which types of VUS could be considered for reporting in prenatal settings. Furthermore, we investigated what the crucial elements are to facilitate rapid management of uncertain results in a prenatal setting. MATERIAL AND METHODS: We reviewed exome results from 451 pregnancies performed in 2019-2021. We analyzed which factors that were taken into account by the multidisciplinary team (MDT) contributed towards decision making on reporting VUS after prenatal exome sequencing. RESULTS: In 9/451 (2%) pregnancies tested with exome sequencing using a broad panel analysis a VUS was reported. After birth 3/9 VUS could be reclassified to likely pathogenic variants based on new clinical follow up data. We considered reporting VUS in genes: 1) matching the fetal phenotype, 2) associated with a severe disorder when a functional test is available or 3) possibly associated with a disorder where early post-partum diagnosis and treatment are crucial for a better prognosis. Two flowcharts were designed to guide first the laboratory specialist and then the MDT in decisions on reporting VUS. The crucial elements that enabled timely decisions on VUS disclosure were regular meetings, appropriate expertise, professional connections with other experts and psychological safety within the MDT. CONCLUSION: In this study three out of nine VUS could be re-classified as likely pathogenic after clinical follow-up. In order to protect pregnant couples from the burden of uncertain results, the genetic professionals have to take the responsibility to limit the reporting of VUS. This can be done not only by automated filtering of data, by following professional guidelines and by building standardized decision flows, but also by discussing individual cases considering personal situations and the involved disease and by sharing professional experience and responsibility in a multidisciplinary prenatal team setting.

"Let's Just Wait Until She's Born": Temporal Factors That Shape Decision-Making for Prenatal Genomic Sequencing Amongst Families Underrepresented in Genomic Research.

Genomic sequencing has been increasingly utilized for prenatal diagnosis in recent years and this trend is likely to continue. However, decision-making for parents in the prenatal period is particularly fraught, and prenatal sequencing would significantly expand the complexity of managing health risk information, reproductive options, and healthcare access. This qualitative study investigates decision-making processes amongst parents who enrolled or declined to enroll in the prenatal arm of the California-based Program in Prenatal and Pediatric Genome Sequencing (P3EGS), a study in the Clinical Sequencing Evidence-Generating Research (CSER) consortium that offered whole exome sequencing for fetal anomalies with a focus on underrepresented groups in genomic research. Drawing on the views of 18 prenatal families who agreed to be interviewed after enrolling (n = 15) or declining to enroll (n = 3) in P3EGS, we observed that the timing of sequencing, coupled with unique considerations around experiences of time during pregnancy and prenatal testing, intersect with structural supports beyond the clinic to produce preferences for and against prenatal sequencing and to contain the threat of unwelcome, uncertain knowledge. Particularly for those without structural supports, finding out consequential information may be more palatable after the birth, when the first stage of the uncertain future has been revealed. Future research should examine the role of temporality in decision-making around prenatal genomic sequencing across diverse population cohorts, in order to observe more precisely the role that structural barriers play in patient preferences.

Optimising Exome Prenatal Sequencing Services (EXPRESS): a study protocol to evaluate rapid prenatal exome sequencing in the NHS Genomic Medicine Service.

Background: Prenatal exome sequencing (ES) for the diagnosis of fetal anomalies was implemented nationally in England in October 2020 by the NHS Genomic Medicine Service (GMS). is the GMS is based around seven regional Genomic Laboratory Hubs (GLHs). Prenatal ES has the potential to significantly improve NHS prenatal diagnostic services by increasing genetic diagnoses and informing prenatal decision-making. Prenatal ES has not previously been offered routinely in a national healthcare system and there are gaps in knowledge and guidance. Methods: Our mixed-methods evaluation commenced in October 2020, aligning with the start date of the NHS prenatal ES service . Study design draws on a framework developed in previous studies of major system innovation. There are five interrelated workstreams. Workstream-1 will use interviews and surveys with professionals, non-participant observations and documentary analysis to produce in-depth case studies across all GLHs. Data collection at multiple time points will track changes over time. In Workstream-2 qualitative interviews with parents offered prenatal ES will explore experiences and establish information and support needs. Workstream-3 will analyse data from all prenatal ES tests for nine-months to establish service outcomes (e.g. diagnostic yield, referral rates, referral sources). Comparisons between GLHs will identify factors (individual or service-related) associated with any variation in outcomes. Workstream-4 will identify and analyse practical ethical problems. Requirements for an effective ethics framework for an optimal and equitable service will be determined. Workstream-5 will assess costs and cost-effectiveness of prenatal ES versus standard tests and evaluate costs of implementing an optimal prenatal ES care pathway. Integration of findings will determine key features of an optimal care pathway from a service delivery, parent and professional perspective. Discussion: The proposed formative and summative evaluation will inform the evolving prenatal ES service to ensure equity of access, high standards of care and benefits for parents across England.

BACKGROUND: Prenatal exome sequencing is a new test that is offered through the NHS Genomic Medicine Service. Prenatal exome sequencing is offered to pregnant women when ultrasound scans suggest that their baby may have a genetic condition that cannot be diagnosed using standard tests. If a genetic condition is diagnosed this can give parents important information about the outlook for their baby. It can also help with their decisions about whether to continue or end the pregnancy, pregnancy management, post-birth care and future pregnancies. STUDY METHODS: The aim of this study is to evaluate the prenatal exome sequencing service. To do this we will; 1. Study how prenatal exome sequencing is delivered across England using surveys and interviews with professionals.2. Interview parents to ask what they think of prenatal exome sequencing and how support and information could be improved3. Look at how many parents have prenatal exome sequencing and the test results. We will look carefully at who has access to the test and whether any particular groups are less likely to be offered testing.4. Conduct workshops with health professionals and parents to identify any practical or ethical problems that arise when prenatal exome sequencing is offered.5. Look at the cost of prenatal exome sequencing and compare it to the cost of other tests that are offered to diagnose genetic conditions in pregnancy.6. Gather our findings together to make recommendations for best practice. Patient and Public Involvement: A patient and public Involvement, engagement and participation (PPIEP) advisory group will work closely with the research team to design the study and develop study materials. They will also help us understand our findings to make sure the information and recommendations that come out of our research will be helpful to parents and the NHS.

Prenatal Exome Sequencing: Background, Current Practice and Future Perspectives-A Systematic Review.

The introduction of Next Generation Sequencing (NGS) technologies has exerted a significant impact on prenatal diagnosis. Prenatal Exome Sequencing (pES) is performed with increasing frequency in fetuses with structural anomalies and negative chromosomal analysis. The actual diagnostic value varies extensively, and the role of incidental/secondary or inconclusive findings and negative results has not been fully ascertained. We performed a systematic literature review to evaluate the diagnostic yield, as well as inconclusive and negative-result rates of pES. Papers were divided in two groups. The former includes fetuses presenting structural anomalies, regardless the involved organ; the latter focuses on specific class anomalies. Available findings on non-informative or negative results were gathered as well. In the first group, the weighted average diagnostic yield resulted 19%, and inconclusive finding rate 12%. In the second group, the percentages were extremely variable due to differences in sample sizes and inclusion criteria, which constitute major determinants of pES efficiency. Diagnostic pES availability and its application have a pivotal role in prenatal diagnosis, though more homogeneity in access criteria and a consensus on clinical management of controversial information management is envisageable to reach widespread use in the near future.