Genetics Of Congenital Heart Disease Research Articles

The Role of Cilia and the Complex Genetics of Congenital Heart Disease

Congenital heart disease (CHD) can affect up to 1% of live births, and despite abundant evidence of a genetic etiology, the genetic landscape of CHD is still not well understood. A large-scale mouse chemical mutagenesis screen for mutations causing CHD yielded a preponderance of cilia-related genes, pointing to a central role for cilia in CHD pathogenesis. The genes uncovered by the screen included genes that regulate ciliogenesis and cilia-transduced cell signaling as well as many that mediate endocytic trafficking, a cell process critical for both ciliogenesis and cell signaling. The clinical relevance of these findings is supported by whole-exome sequencing analysis of CHD patients that showed enrichment for pathogenic variants in ciliome genes. Surprisingly, among the ciliome CHD genes recovered were many that encoded direct protein–protein interactors. Assembly of the CHD genes into a protein–protein interaction network yielded a tight interactome that suggested this protein–protein interaction may have functional importance and that its disruption could contribute to the pathogenesis of CHD. In light of these and other findings, we propose that an interactome enriched for ciliome genes may provide the genomic context for the complex genetics of CHD and its often-observed incomplete penetrance and variable expressivity.

Clinical Decision Analysis of Genetic Evaluation and Testing in 1013 Intensive Care Unit Infants with Congenital Heart Defects Supports Universal Genetic Testing.

Extracardiac anomalies (ECAs) are strong predictors of genetic disorders in infants with congenital heart disease (CHD), but there are no prior studies assessing performance of ECA status as a screen for genetic diagnoses in CHD patients. This retrospective cohort study assessed this in our comprehensive inpatient CHD genetics service focusing on neonates and infants admitted to the intensive care unit (ICU). The performance and diagnostic utility of using ECA status to screen for genetic disorders was assessed using decision curve analysis, a statistical tool to assess clinical utility, determining the threshold of phenotypic screening by ECA versus a Test-All approach. Over 24% of infants had genetic diagnoses identified (n = 244/1013), and ECA-positive status indicated a 4-fold increased risk of having a genetic disorder. However, ECA status had low-moderate screening performance based on predictive summary index, a compositive measure of positive and negative predictive values. For those with genetic diagnoses, nearly one-third (32%, 78/244) were ECA-negative but had cytogenetic and/or monogenic disorders identified by genetic testing. Thus, if the presence of multiple congenital anomalies is the phenotypic driver to initiate genetic testing, 13.4% (78/580) of infants with isolated CHD with identifiable genetic causes will be missed. Given the prevalence of genetic disorders and limited screening performance of ECA status, this analysis supports genetic testing in all CHD infants in intensive care settings rather than screening based on ECA.

Genetics and etiology of congenital heart disease.

Congenital heart disease (CHD) is the most common severe birth anomaly, affecting almost 1% of infants. Most CHD is genetic, but only 40% of patients have an identifiable genetic risk factor for CHD. Chromosomal variation contributes significantly to CHD but is not readily amenable to biological follow-up due to the number of affected genes and lack of evolutionary synteny. The first CHD genes were implicated in extended families with syndromic CHD based on the segregation of risk alleles in affected family members. These have been complemented by more CHD gene discoveries in large-scale cohort studies. However, fewer than half of the 440 estimated human CHD risk genes have been identified, and the molecular mechanisms underlying CHD genetics remains incompletely understood. Therefore, model organisms and cell-based models are essential tools for improving our understanding of cardiac development and CHD genetic risk. Recent advances in genome editing, cell-specific genetic manipulation of model organisms, and differentiation of human induced pluripotent stem cells have recently enabled the characterization of developmental stages. In this chapter, we will summarize the latest studies in CHD genetics and the strengths of various study methodologies. We identify opportunities for future work that will continue to further CHD knowledge and ultimately enable better diagnosis, prognosis, treatment, and prevention of CHD.

Consanguinity and Congenital Heart Disease Susceptibility: Insights into Rare Genetic Variations in Saudi Arabia.

Congenital heart disease (CHD) encompasses a wide range of structural defects of the heart and, in many cases, the factors that predispose an individual to disease are not well understood, highlighting the remarkable complexity of CHD etiology. Evidence of familial aggregation of CHD has been demonstrated in different communities and for different cardiac lesions. Consanguinity, particularly among first cousins, is an added risk factor for these families, particularly in societies where it is considered a common cultural practice, as confirmed in previous studies conducted in Saudi Arabia and other countries. Through comprehensive genetic testing of affected families, we have been able to better understand the genetic basis of the various cardiac lesions and to delineate the molecular mechanisms involved in cardiac morphogenesis. In this review, we discuss the epidemiology and genetics of CHD in consanguineous populations focusing on Saudi Arabia as an extensive study model to address current advances and challenges in the clinical genetic diagnosis and prevention of CHD.

THE ROLE OF GENETICS IN THE UNDERSTANDING OF COMPLEX CONGENITAL HEART DISEASES

One of the most dynamic organs in the human body is the heart. Cardiac development is regulated by two key factors including signaling and transcriptional pathways. Thus, during the development of the fetus, any factor that disrupts the normal functioning of these factors may lead toward congenital heart defects (CHDs). Congenital heart disease is a complex multifactorial disease that involves both environmental and genetic factors.1,2 It is defined as any defect that occurs during heart development either in the cardiac structure or its associated vessels.3 Globally, it is one of the most common reasons for infant mortality and one of the most common birth defects in paediatric patients. As a rough estimate, 8 infants in every thousand live births are born with this fatal disease.4 Every year, in Pakistan approximately 40,000 children suffered from CHDs.5 Clinically depending upon the disease severity congenital heart diseases can be divided into two major subgroups one is non-syndromic and the other is syndromic. And among all these defects cardiac septation defects are the most common accounting for approximately 50% of the cases.6 It can be further sub-grouped as isolated lesions or complex diseases in combination with other heart defects.3 The exact mechanism involved in the pathogenesis of the congenital heart remains poorly understood but the most probable mechanism is multifactorial. Recent investigations suggest the role of epigenetic factors, micro RNA and small non-coding RNAs in the development of congenital heart defects. Moreover, advancements in molecular techniques including next-generation sequencing (NGS) helps in further detecting the genetic causes of CHDs such as the novel single nucleotide polymorphisms (SNPs) and copy number variants (CNVs).7 The current approaches used for genetic diagnosis of paediatric patients suffering from CHDs include karyotype analysis, copy number variation analysis, next-generation sequencing, and whole-genome or whole-exome sequencing. The targeted NGS relies on the selected region of know gene of interest and compared to whole genome or exome sequencing it provides us deeper gene coverage with easy variant detection at a lower cost. It provides robust detection of deletions, insertion and single nucleotide polymorphisms which chromosomal microarray analysis (CMA) and karyotyping cannot detect. To date, many pathogenic variants in different genes such as CITED2, CHD7, ZFPM2, MYH6 and KMT2D have been investigated by using targeted NGS. While whole-exome or genome sequencing help in the discovery of genes involves in the pathogenesis of congenital heart defects as it gives us more resolution at a single base-pair level. Thus accurate genetic diagnosis can be done by using the appropriate diagnostic techniques that can ultimately help in better patient counseling and clinical outcome.8 Furthermore, personalized medicines or finding mutations responsible for individual congenital heart disease patients can direct to better outcomes and approaches for each cardiac malformation phenotype. Thus, ultimately combined data of patients genotypic and phenotypic following well-designed guidelines will accelerate the translation of each SNP information into better treatment and clinical insights.9 Keywords: NGS, Single nucleotide polymorphisms, CHDs.

The Congenital Heart Disease Genetics Clinic: Evolving the Model of Care

The Congenital Heart Disease Genetics Clinic: Evolving the Model of Care

The genetics of congenital heart disease: The role of advanced genomic approaches

As the leading non-infectious cause of paediatric morbidity and mortality worldwide, congenital heart disease (CHD) is a significant social and healthcare burden, especially in low- and lower-middle-income countries, including South Africa. The aetiology of CHD is poorly understood, though heritable genetic factors have been shown to contribute to the risk of CHD in individuals of European ancestry. In this review, we highlight the impact that advanced genomic approaches have had on the understanding of the role of genetics in CHD. We also summarise current knowledge of the genetics of CHD in Africa, and the challenges and opportunities for conducting genomic research in these populations. Chromosomal microarrays and next-generation sequencing platforms allow for high-throughput screening of patients for genetic mutations and show great potential for the identification of genetic causes of CHD. Advancing our understanding of the genetic architecture and risk factors associated with CHD in patients of African descent is the fi rst step towards improving CHD diagnosis and management. Therefore, exploring the genetics of CHD has the potential to improve the quality of life for children born with CHD in Africa, by enabling clinicians to identify familial inheritance patterns and predict recurrent risks and prognostic outcomes pre- and post-surgical intervention.

Genetics of congenital heart disease: a narrative review of recent advances and clinical implications.

Congenital heart disease (CHD) is the most common human birth defect and remains a leading cause of mortality in childhood. Although advances in clinical management have improved the survival of children with CHD, adult survivors commonly experience cardiac and non-cardiac comorbidities, which affect quality of life and prognosis. Therefore, the elucidation of genetic etiologies of CHD not only has important clinical implications for genetic counseling of patients and families but may also impact clinical outcomes by identifying at-risk patients. Recent advancements in genetic technologies, including massively parallel sequencing, have allowed for the discovery of new genetic etiologies for CHD. Although variant prioritization and interpretation of pathogenicity remain challenges in the field of CHD genomics, advances in single-cell genomics and functional genomics using cellular and animal models of CHD have the potential to provide novel insights into the underlying mechanisms of CHD and its associated morbidities. In this review, we provide an updated summary of the established genetic contributors to CHD and discuss recent advances in our understanding of the genetic architecture of CHD along with current challenges with the interpretation of genetic variation. Furthermore, we highlight the clinical implications of genetic findings to predict and potentially improve clinical outcomes in patients with CHD.

Current Insights into Genetics of Congenital Heart Diseases: GATA and T-box Cardiac Transcription Factors as the Hotspot Pathogenesis

Current Insights into Genetics of Congenital Heart Diseases: GATA and T-box Cardiac Transcription Factors as the Hotspot Pathogenesis

The Role of Epigenetics in Congenital Heart Disease.

Congenital heart disease (CHD) is the most common birth defect among newborns worldwide and contributes to significant infant morbidity and mortality. Owing to major advances in medical and surgical management, as well as improved prenatal diagnosis, the outcomes for these children with CHD have improved tremendously so much so that there are now more adults living with CHD than children. Advances in genomic technologies have discovered the genetic causes of a significant fraction of CHD, while at the same time pointing to remarkable complexity in CHD genetics. For this reason, the complex process of cardiogenesis, which is governed by multiple interlinked and dose-dependent pathways, is a well investigated process. In addition to the sequence of the genome, the contribution of epigenetics to cardiogenesis is increasingly recognized. Significant progress has been made dissecting the epigenome of the heart and identified associations with cardiovascular diseases. The role of epigenetic regulation in cardiac development/cardiogenesis, using tissue and animal models, has been well reviewed. Here, we curate the current literature based on studies in humans, which have revealed associated and/or causative epigenetic factors implicated in CHD. We sought to summarize the current knowledge on the functional role of epigenetics in cardiogenesis as well as in distinct CHDs, with an aim to provide scientists and clinicians an overview of the abnormal cardiogenic pathways affected by epigenetic mechanisms, for a better understanding of their impact on the developing fetal heart, particularly for readers interested in CHD research.

Race and Genetics in Congenital Heart Disease: Application of iPSCs, Omics, and Machine Learning Technologies.

Congenital heart disease (CHD) is a multifaceted cardiovascular anomaly that occurs when there are structural abnormalities in the heart before birth. Although various risk factors are known to influence the development of this disease, a full comprehension of the etiology and treatment for different patient populations remains elusive. For instance, racial minorities are disproportionally affected by this disease and typically have worse prognosis, possibly due to environmental and genetic disparities. Although research into CHD has highlighted a wide range of causal factors, the reasons for these differences seen in different patient populations are not fully known. Cardiovascular disease modeling using induced pluripotent stem cells (iPSCs) is a novel approach for investigating possible genetic variants in CHD that may be race specific, making it a valuable tool to help solve the mystery of higher incidence and mortality rates among minorities. Herein, we first review the prevalence, risk factors, and genetics of CHD and then discuss the use of iPSCs, omics, and machine learning technologies to investigate the etiology of CHD and its connection to racial disparities. We also explore the translational potential of iPSC-based disease modeling combined with genome editing and high throughput drug screening platforms.

Decoding Genetics of Congenital Heart Disease Using Patient-Derived Induced Pluripotent Stem Cells (iPSCs).

Congenital heart disease (CHD) is the most common cause of infant death associated with birth defects. Recent next-generation genome sequencing has uncovered novel genetic etiologies of CHD, from inherited and de novo variants to non-coding genetic variants. The next phase of understanding the genetic contributors of CHD will be the functional illustration and validation of this genome sequencing data in cellular and animal model systems. Human induced pluripotent stem cells (iPSCs) have opened up new horizons to investigate genetic mechanisms of CHD using clinically relevant and patient-specific cardiac cells such as cardiomyocytes, endothelial/endocardial cells, cardiac fibroblasts and vascular smooth muscle cells. Using cutting-edge CRISPR/Cas9 genome editing tools, a given genetic variant can be corrected in diseased iPSCs and introduced to healthy iPSCs to define the pathogenicity of the variant and molecular basis of CHD. In this review, we discuss the recent progress in genetics of CHD deciphered by large-scale genome sequencing and explore how genome-edited patient iPSCs are poised to decode the genetic etiologies of CHD by coupling with single-cell genomics and organoid technologies.

Variants of significance: medical genetics and surgical outcomes in congenital heart disease

This article reviews the current understanding and limitations in knowledge of the effect genetics and genetic diagnoses have on perioperative and postoperative surgical outcomes in patients with congenital heart disease (CHD). Presence of a known genetic diagnosis seems to effect multiple significant outcome metrics in CHD surgery including length of stay, need for extracorporeal membrane oxygenation, mortality, bleeding, and heart failure. Data regarding the effects of genetics in CHD is complicated by lack of standard genetic assessment resulting in inaccurate risk stratification of patients when analyzing data. Only 30% of variation in CHD surgical outcomes are explained by currently measured variables, with 2.5% being attributed to diagnosed genetic disorders, it is thought a significant amount of the remaining outcome variation is because of unmeasured genetic factors. Genetic diagnoses clearly have a significant effect on surgical outcomes in patients with CHD. Our current understanding is limited by lack of consistent genetic evaluation and assessment as well as evolving knowledge and discovery regarding the genetics of CHD. Standardizing genetic assessment of patients with CHD will allow for the best risk stratification and ultimate understanding of these effects.

Genetic Contribution to Congenital Heart Disease (CHD).

Congenital heart defects (CHD) are the most common congenital problems in neonates. The basis for CHD is multifactorial, involving genetic and environmental components. The elucidation of genetic components remains difficult because it is a genetically heterogeneous disease. Currently, the major identified genetic causes include chromosomal abnormalities, large subchromosomal deletions/duplications, and point mutations. However, much more remains to be unraveled. An important insight from the research on the genetics of CHD is that any change at the genetic level that alters the dosage of genes required in any process during heart development results in a developmental defect. The use of conventional gene identification (linkage analysis and direct targeted sequencing) methods followed by the rapid advancements in high-throughput technologies (copy number variant platforms, SNP arrays, and next-generation sequencing) has identified an extensive list of genetic causes. However, the most common presentation of CHD is in the form of sporadic cases. Therefore, it is important to identify their underlying genetic cause. In this review, we revisit the causal genetic factors of CHD and discuss the clinical implications of research in the field.

Genetics of Congenital Heart Disease.

Congenital heart disease (CHD) is one of the most common birth defects. Studies in animal models and humans have indicated a genetic etiology for CHD. About 400 genes have been implicated in CHD, encompassing transcription factors, cell signaling molecules, and structural proteins that are important for heart development. Recent studies have shown genes encoding chromatin modifiers, cilia related proteins, and cilia-transduced cell signaling pathways play important roles in CHD pathogenesis. Elucidating the genetic etiology of CHD will help improve diagnosis and the development of new therapies to improve patient outcomes.

SHROOM3 is a novel component of the planar cell polarity pathway whose disruption causes congenital heart disease

Congenital heart disease (CHD) is the most common cause of death due to birth defects. Despite CHD frequency, the etiology remains mostly unknown. Understanding CHD genetics and elucidating disease mechanism will help establish prognosis, identify comorbidity risks, and develop targeted therapies. CHD often results from disrupted cytoarchitecture and signaling pathways. We have identified a novel CHD candidate SHROOM3, a protein associated with the actin cytoskeleton and the Wnt/Planar Cell Polarity (PCP) signaling pathway. SHROOM3 induces actomyosin constriction within the apical side of cells and is implicated in neural tube defects and chronic renal failure in humans. A recent study demonstrated that SHROOM3 interacts with Dishevelled2 (DVL2), a component of the PCP signaling pathway, suggesting that SHROOM3 serves as an important link between acto-myosin constriction and PCP signaling. PCP signaling establishes cell polarity required for multiple developmental processes, and is required for cardiac development. In Preliminary data we utilized a Shroom3 gene-trap mouse (Shroom3gt/gt) to demonstrated that SHROOM3 disruption leads to cardiac defects phenocopy PCP disruption. We also demonstrate that patients with CHD phenotypes have rare and potentially damaging SHROOM3 variants within SHROOM3’s PCP-binding domain. We hypothesize SHROOM3 is a novel terminal effector of PCP signaling, and disruption is a novel contributor to CHD. To test this, we assessed genetic interaction between SHROOM3 and PCP during cardiac development and the ultimate effect on cell structure and movement. Heterozygous Shroom3+/gt mice and heterozygous Dvl2 +/- mice are phenotypically normal. We demonstrated genetic interaction between SHROOM3 and PCP signaling by generating compound heterozygous Shroom3+/gt ;Dvl2 +/- mice and identifying a Double Outlet Right Ventricle and Ventricular Septal Defect in one embryo. We also observed fewer compound heterozygous mice than anticipated by Mendelian rations (observed: 18.4%; expected: 25%; n=76), suggesting potential lethality in utero. Immunohistochemistry demonstrates disrupted actomyosin in the SHROOM3gt/gt mice, characteristic of PCP disruption. These data help strengthen SHROOM3 as a novel CHD candidate gene and a component of the PCP Signaling pathway. Further characterization of this gene is important for CHD diagnosis and therapeutic development.

Abstract 16747: High Incidence of Congenital Heart Defects in a Dominant Mouse Forward Genetic Screen Using Fetal Echocardiography

Introduction: Congenital heart disease (CHD) is largely sporadic and suggested to be largely mediated by non-Mendelian or complex genetics. We previously showed the efficacy of mouse mutagenesis in recovering recessive mutations causing CHD. Here we hypothesize the complex genetics of human CHD can be modeled in mice using a sensitized mutagenesis screen for dominant mutations causing CHD. Methods: C57BL/6J mice were mutagenized using ethylnirosourea, then mated with C57BL/6J mice to generate G1 males that were further mated to females harboring heterozygous “driver” mutation ( Kif7, Anks6, Sap130 ) that can cause CHD when in homozygosity. The G2 fetuses generated by each G1 male were considered a pedigree and were ultrasound scanned (US) at E13.5-19.5 using a 40 MHz transducer with the Vevo2100 ultrasound system. Results: We US scanned 17,750 fetuses from 487 G1 pedigrees, yielding 123 fetuses with CHD from 90 G1 lines (Table 1A). Interestingly, the overall incidence of CHD (0.69%) is similar to that observed in the previous recessive mutagenesis screen (0.76%) (Table 1A). Surprisingly, no laterality mutants were recovered compared to the 2.2% recovered in the recessive screen (Table 1A). Regardless of the driver mutations, similar spectrum of CHD was observed (Table 1B). Besides VSD, the predominant CHD phenotype observed was double outlet right ventricle and overriding aorta (Fig.1) and atrioventricular septal defect (Table 1B). Conclusion: We showed the feasibility of using mice to model dominant mutations causing CHD. The incidence of CHD observed in the dominant screen was similar to that of the recessive screen, indicating the genetics of CHD in mice and human are similar.

Genetic evaluation of patients with congenital heart disease.

Purpose of reviewThe aim of this study is to review genetics of congenital heart disease (CHD) with a focus on clinical applications, genetic testing and clinical challenges.Recent findingsWith improved clinical care, there is a rapidly expanding population of adults, especially women, with CHD who have not undergone contemporary genetic assessment and do not understand their risk for having a child with CHD. Many patients have never undergone assessment or had genetic testing. A major barrier is medical geneticist availability, resulting in this burden of care shifting to providers outside of genetics. Even with current understanding, the cause for the majority of cases of CHD is still not known. There are significant gaps in knowledge in the realms of more complex causes such as noncoding variants, multigenic contribution and small structural chromosomal anomalies.SummaryStandard assessment of patients with CHD, including adult survivors, is indicated. The best first-line genetic assessment for most patients with CHD is a chromosomal microarray, and this will soon evolve to be genomic sequencing with copy number variant analysis. Due to lack of medical geneticists, creative solutions to maximize the number of patients with CHD who undergo assessment with standard protocols and plans for support with result interpretation need to be explored.

Young at Heart: Recent Advances in the Genetics of Congenital Heart Disease and Translational Care

Young at Heart: Recent Advances in the Genetics of Congenital Heart Disease and Translational Care

The genetics of congenital heart disease… understanding and improving long-term outcomes in congenital heart disease: a review for the general cardiologist and primary care physician.

This review has two purposes: to provide an updated review of the genetic causes of congenital heart disease (CHD) and the clinical implications of these genetic mutations, and to provide a clinical algorithm for clinicians considering a genetics evaluation of a CHD patient. A large portion of congenital heart disease is thought to have a significant genetic contribution, and at this time a genetic cause can be identified in approximately 35% of patients. Through the advances made possible by next generation sequencing, many of the comorbidities that are frequently seen in patients with genetic congenital heart disease patients can be attributed to the genetic mutation that caused the congenital heart disease. These comorbidities are both cardiac and noncardiac and include: neurodevelopmental disability, pulmonary disease, heart failure, renal dysfunction, arrhythmia and an increased risk of malignancy. Identification of the genetic cause of congenital heart disease helps reduce patient morbidity and mortality by improving preventive and early intervention therapies to address these comorbidities. Through an understanding of the clinical implications of the genetic underpinning of congenital heart disease, clinicians can provide care tailored to an individual patient and continue to improve the outcomes of congenital heart disease patients.