Brachmann-de Lange syndrome with congenital diaphragmatic hernia and NIPBL gene mutation

Congenital diaphragmatic hernia in Coffin Siris syndrome: Further evidence from two cases

Coffin-Siris Syndrome (CSS) is a rare multi-system dominant condition with a variable clinical presentation mainly characterized by hypoplasia/aplasia of the nail and/or distal phalanx of the fifth digit, coarse facies, hirsutism/hypertrichosis, developmental delay and intellectual disability of variable degree and growth impairment. Congenital anomalies may include cardiac, genitourinary and central nervous system malformations whereas congenital diaphragmatic hernia (CDH) is rarely reported. The genes usually involved in CSS pathogenesis are ARID1B (most frequently), SMARCA4, SMARCB1, ARID1A, SMARCE1, DPF2, and PHF6. Here, we present two cases of CSS presenting with CDH, for whom Whole Exome Sequencing (WES) identified two distinct de novo heterozygous causative variants, one in ARID1B (case 1) and one in SMARCA4 (case 2). Due to the rarity of CDH in CSS, in both cases the occurrence of CDH did not represent a predictive sign of CSS but, on the other hand, prompted genetic testing before (case 1) or independently (case 2) from the clinical hypothesis of CSS. We provide further evidence of the association between CSS and CDH, reviewed previous cases from literature and discuss possible functional links to related conditions.

Underlying genetic etiologies of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is often detectable prenatally. Advances in genetic testing have made it possible to obtain a molecular diagnosis in many fetuses with CDH. Here, we review the aneuploidies, copy number variants (CNVs), and single genes that have been clearly associated with CDH. We suggest that array-based CNV analysis, with or without a chromosome analysis, is the optimal test for identifying chromosomal abnormalities and CNVs in fetuses with CDH. To identify causative sequence variants, whole exome sequencing (WES) is the most comprehensive strategy currently available. Whole genome sequencing (WGS) with CNV analysis has the potential to become the most efficient and effective means of identifying an underlying diagnosis but is not yet routinely available for prenatal diagnosis. We describe how to overcome and address the diagnostic and clinical uncertainty that may remain after genetic testing, and review how a molecular diagnosis may impact recurrence risk estimations, mortality rates, and the availability and outcomes of fetal therapy. We conclude that after the prenatal detection of CDH, patients should be counseled about the possible genetic causes of the CDH, and the genetic testing modalities available to them, in accordance with generally accepted guidelines for pretest counseling in the prenatal setting.

Genetic Diagnostic Strategies and Counseling for Families Affected by Congenital Diaphragmatic Hernia

Congenital diaphragmatic hernia (CDH) is a relatively common and severe birth defect with variable clinical outcome and associated malformations in up to 60% of patients. Mortality and morbidity remain high despite advances in pre-, intra-, and postnatal management. We review the current literature and give an overview about the genetics of CDH to provide guidelines for clinicians with respect to genetic diagnostics and counseling for families. Until recently, the common practice was (molecular) karyotyping or chromosome microarray if the CDH diagnosis is made prenatally with a 10% diagnostic yield. Undiagnosed patients can be reflexed to trio exome/genome sequencing with an additional diagnostic yield of 10 to 20%. Even with a genetic diagnosis, there can be a range of clinical outcomes. All families with a child with CDH with or without additional malformations should be offered genetic counseling and testing in a family-based trio approach.

The Role of De Novo Variants in Patients with Congenital Diaphragmatic Hernia

The genetic etiology of congenital diaphragmatic hernia (CDH), a common and severe birth defect, is still incompletely understood. Chromosomal aneuploidies, copy number variations (CNVs), and variants in a large panel of CDH-associated genes, both de novo and inherited, have been described. Due to impaired reproductive fitness, especially of syndromic CDH patients, and still significant mortality rates, the contribution of de novo variants to the genetic background of CDH is assumed to be high. This assumption is supported by the relatively low recurrence rate among siblings. Advantages in high-throughput genome-wide genotyping and sequencing methods have recently facilitated the detection of de novo variants in CDH. This review gives an overview of the known de novo disease-causing variants in CDH patients.

Exome hits demystified: The next frontier

Severe mental illnesses such as schizophrenia and bipolar disorder have complex inheritance patterns, involving both common and rare variants. Whole exome sequencing is a promising approach to find out the rare genetic variants. We had previously reported several rare variants in multiplex families with severe mental illnesses. The current article tries to summarise the biological processes and pattern of expression of genes harbouring the aforementioned variants, linking them to known clinical manifestations through a methodical narrative review. Of the 28 genes considered for this review from 7 families with multiple affected individuals, 6 genes are implicated in various neuropsychiatric manifestations including some variations in the brain morphology assessed by magnetic resonance imaging. Another 15 genes, though associated with neuropsychiatric manifestations, did not have established brain morphological changes whereas the remaining 7 genes did not have any previously recorded neuropsychiatric manifestations at all. Wnt/b-catenin signaling pathway was associated with 6 of these genes and PI3K/AKT, calcium signaling, ERK, RhoA and notch signaling pathways had at least 2 gene associations. We present a comprehensive review of biological and clinical knowledge about the genes previously reported in multiplex families with severe mental illness. A 'disease in dish approach' can be helpful to further explore the fundamental mechanisms.

Unraveling the Genetics of Congenital Diaphragmatic Hernia: An Ongoing Challenge

Congenital diaphragmatic hernia (CDH) is a congenital structural anomaly in which the diaphragm has not developed properly. It may occur either as an isolated anomaly or with additional anomalies. It is thought to be a multifactorial disease in which genetic factors could either substantially contribute to or directly result in the developmental defect. Patients with aneuploidies, pathogenic variants or de novo Copy Number Variations (CNVs) impacting specific genes and loci develop CDH typically in the form of a monogenetic syndrome. These patients often have other associated anatomical malformations. In patients without a known monogenetic syndrome, an increased genetic burden of de novo coding variants contributes to disease development. In early years, genetic evaluation was based on karyotyping and SNP-array. Today, genomes are commonly analyzed with next generation sequencing (NGS) based approaches. While more potential pathogenic variants are being detected, analysis of the data presents a bottleneck-largely due to the lack of full appreciation of the functional consequence and/or relevance of the detected variant. The exact heritability of CDH is still unknown. Damaging de novo alterations are associated with the more severe and complex phenotypes and worse clinical outcome. Phenotypic, genetic-and likely mechanistic-variability hampers individual patient diagnosis, short and long-term morbidity prediction and subsequent care strategies. Detailed phenotyping, clinical follow-up at regular intervals and detailed registries are needed to find associations between long-term morbidity, genetic alterations, and clinical parameters. Since CDH is a relatively rare disorder with only a few recurrent changes large cohorts of patients are needed to identify genetic associations. Retrospective whole genome sequencing of historical patient cohorts using will yield valuable data from which today's patients and parents will profit Trio whole genome sequencing has an excellent potential for future re-analysis and data-sharing increasing the chance to provide a genetic diagnosis and predict clinical prognosis. In this review, we explore the pitfalls and challenges in the analysis and interpretation of genetic information, present what is currently known and what still needs further study, and propose strategies to reap the benefits of genetic screening.

The influence of genetics in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect that is associated with significant morbidity and mortality, especially when associated with additional congenital anomalies. Both environmental and genetic factors are thought to contribute to CDH. The genetic contributions to CDH are highly heterogeneous and incompletely defined. No one genetic cause accounts for more than 1-2% of CDH cases. In this review, we summarize the known genetic causes of CDH from chromosomal anomalies to individual genes. Both de novo and inherited variants contribute to CDH. Genes causing CDH are increasingly identified from animal models and from genomic strategies including exome and genome sequencing in humans. CDH genes are often transcription factors, genes involved in cell migration or the components of extracellular matrix. We provide clinical genetic testing strategies in the clinical evaluation that can identify a genetic cause in up to ∼30% of patients with non-isolated CDH and can be useful to refine prognosis, identify associated medical and neurodevelopmental issues to address, and inform family planning options.

Diagnosis and management of Cornelia de Lange syndrome: first international consensus statement

Cornelia de Lange syndrome (CdLS) is an archetypical genetic syndrome that is characterized by intellectual disability, well-defined facial features, upper limb anomalies and atypical growth, among numerous other signs and symptoms. It is caused by variants in any one of seven genes, all of which have a structural or regulatory function in the cohesin complex. Although recent advances in next-generation sequencing have improved molecular diagnostics, marked heterogeneity exists in clinical and molecular diagnostic approaches and care practices worldwide. Here, we outline a series of recommendations that document the consensus of a group of international experts on clinical diagnostic criteria, both for classic CdLS and non-classic CdLS phenotypes, molecular investigations, long-term management and care planning.

Congenital diaphragmatic hernias: from genes to mechanisms to therapies

Congenital diaphragmatic hernias (CDHs) and structural anomalies of the diaphragm are a common class of congenital birth defects that are associated with significant morbidity and mortality due to associated pulmonary hypoplasia, pulmonary hypertension and heart failure. In ∼30% of CDH patients, genomic analyses have identified a range of genetic defects, including chromosomal anomalies, copy number variants and sequence variants. The affected genes identified in CDH patients include transcription factors, such as GATA4, ZFPM2, NR2F2 and WT1, and signaling pathway components, including members of the retinoic acid pathway. Mutations in these genes affect diaphragm development and can have pleiotropic effects on pulmonary and cardiac development. New therapies, including fetal endoscopic tracheal occlusion and prenatal transplacental fetal treatments, aim to normalize lung development and pulmonary vascular tone to prevent and treat lung hypoplasia and pulmonary hypertension, respectively. Studies of the association between particular genetic mutations and clinical outcomes should allow us to better understand the origin of this birth defect and to improve our ability to predict and identify patients most likely to benefit from specialized treatment strategies.

Genetic causes of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a moderately prevalent birth defect that, despite advances in neonatal care, is still a significant cause of infant death, and surviving patients have significant morbidity. The goal of ongoing research to elucidate the genetic causes of CDH is to develop better treatment and ultimately prevention. CDH is a complex developmental defect that is etiologically heterogeneous. This review summarizes the recurrent genetic causes of CDH including aneuploidies, chromosome copy number variants, and single gene mutations. It also discusses strategies for genetic evaluation and genetic counseling in an era of rapidly evolving technologies in clinical genetic diagnostics.

The genetics of common disorders - congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high mortality and morbidity. Although numerous chromosomal aberrations and gene mutations have been associated with CDH, the etiology of the diaphragmatic defect is identified in less than 50% of patients. This review discusses the some of the more frequent, recurrent karyotypic abnormalities in which CDH is a feature, including 15q26, 8p23.1 and 4p16.3 deletions and tetrasomy 12p (Pallister-Killian syndrome), together with some of the syndromes in which CDH is a relatively common feature, including Fryns syndrome, Matthew-Wood syndrome, overgrowth syndromes and Donnai-Barrow syndrome. In the era of genomic technologies, our knowledge of the genes and chromosome regions involved in pathogenesis of CDH is likely to advance significantly.

Genomic imbalances in patients with a clinical presentation in the spectrum of Cornelia de Lange syndrome

Background

Cornelia de Lange syndrome (CdLS) is a rare autosomal-dominant disorder characterised by facial dysmorphism, growth and psychomotor developmental delay and skeletal defects. To date, causative mutations in the NIPBL (cohesin regulator) and SMC1A (cohesin structural subunit) genes account for > 50% and 6% of cases, respectively.

Methods

We recruited 50 patients with a CdLS clinical diagnosis or with features that overlap with CdLS, who were negative for mutations at NIPBL and SMC1A at molecular screening. Chromosomal rearrangements accounting for the clinical diagnosis were screened for using array Comparative Genomic Hybridisation (aCGH).

Results

Four patients were shown to carry imbalances considered to be candidates for having pathogenic roles in their clinical phenotypes: patient 1 had a 4.2 Mb de novo deletion at chromosome 20q11.2-q12; patient 2 had a 4.8 Mb deletion at chromosome 1p36.23-36.22; patient 3 carried an unbalanced translocation, t(7;17), with a 14 Mb duplication of chromosome 17q24.2-25.3 and a 769 Kb deletion at chromosome 7p22.3; patient 4 had an 880 Kb duplication of chromosome 19p13.3, for which his mother, who had a mild phenotype, was also shown to be a mosaic.

Conclusions

Notwithstanding the variability in size and gene content of the rearrangements comprising the four different imbalances, they all map to regions containing genes encoding factors involved in cell cycle progression or genome stability. These functional similarities, also exhibited by the known CdLS genes, may explain the phenotypic overlap between the patients included in this study and CdLS. Our findings point to the complexity of the clinical diagnosis of CdLS and confirm the existence of phenocopies, caused by imbalances affecting multiple genomic regions, comprising 8% of patients included in this study, who did not have mutations at NIPBL and SMC1A. Our results suggests that analysis by aCGH should be recommended for CdLS spectrum cases with an unexplained clinical phenotype and included in the flow chart for diagnosis of cases with a clinical evaluation in the CdLS spectrum.