Congenital cardiovascular malformations: questions on inheritance. Baltimore-Washington Infant Study Group

Clinical Potential of Misshapen/NIKs-Related Kinase (MINK) 1-A Many-Sided Element of Cell Physiology and Pathology

Misshapen/NIKs-related kinase (MINK) 1 belongs to the mammalian germinal center kinase (GCK) family. It contains the N-terminal, conserved kinase domain, a coiled-coil region, a proline-rich region, and a GCK, C-terminal domain with the Citron-NIK-Homology (CNH) domain. The kinase is an essential component of cellular signaling pathways, which include Wnt signaling, JNK signaling, pathways engaging Ras proteins, the Hippo pathway, and STRIPAK complexes. It thus contributes to regulating the cell cycle, apoptosis, cytoskeleton organization, cell migration, embryogenesis, or tissue homeostasis. MINK1 plays an important role in immunological responses, inhibiting Th17 and Th1 cell differentiation and regulating NLRP3 inflammasome function. It may be considered a link between ROS and the immunological system, and a potential antiviral target for human enteroviruses. The kinase has been implicated in the pathogenesis of sepsis, rheumatoid arthritis, asthma, SLE, and more. It is also involved in tumorigenesis and drug resistance in cancer. Silencing MINK1 reduces cancer cell migration, suggesting potential for new therapeutic approaches. Targeting MINK1 could be a promising treatment strategy for patients insensitive to current chemotherapies, and could improve their prognosis. Moreover, MINK1 plays an important role in the nervous system and the cardiovascular system development and function. The modulation of MINK1 activity could influence the course of neurodegenerative diseases, including Alzheimer's disease. Further exploration of the activity of the kinase could also help in gaining more insight into factors involved in thrombosis or congenital heart disease. This review aims to summarize the current knowledge on MINK1, highlight its therapeutic and prognostic potential, and encourage more studies in this area.

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.

Functional analysis of HECA variants identified in congenital heart disease in the Chinese population

Background

Congenital heart disease (CHD) is a class of cardiovascular defects that includes septal defects, outflow tract abnormalities, and valve defects. Human homolog of Drosophila headcase (HECA) is a novel cell cycle regulator whose role in CHD has not been elucidated. This is the first study to determine the frequency of HECA mutations in patients with CHD and the association between HECA variants and CHD.

Methods

In this study, we identified a candidate gene, HECA, by whole‐exome sequencing of an atrial septal defect family. To investigate the association between HECA variants and CHD risk, targeted exon sequencing was conducted in 689 individuals with sporadic CHD. We further analyzed the effect of HECA gene abnormalities on cardiomyocyte phenotype behavior and related signaling pathways by Western blotting, reverse transcription‐quantitative polymerase chain reaction, and scratch assay.

Results

We found a novel de novo mutation, c.409_410insA (p. W137fs), in the HECA gene and identified five rare deleterious variants that met the filtering criteria in 689 individuals with sporadic CHD. Fisher's exact test revealed a significant association between HECA variations and CHD compared with those in gnomADv2‐East Asians(p = 0.0027). Further functional analysis suggested that the variant p. W137fs resulted in a deficiency of the normal HECA protein, and HECA deficiency altered AC16 cell cycle progression, increased cell proliferation, and migration, and promoted the activation of the PDGF‐BB/PDGFRB/AKT pathway.

Conclusions

Our study identified HECA and its six rare variants, expanding the spectrum of genes associated with CHD pathogenesis in the Chinese population.

Concomitant genetic defects potentiate the adverse impact of prenatal alcohol exposure on cardiac outflow tract maturation

BACKGROUND

Prenatal alcohol exposure (PAE) is associated with an increased incidence of congenital heart defects (CHD), in particular outflow tract (OFT) defects. However, the variability in the incidence of CHD following PAE has not been fully explored. We hypothesize that a concomitant, relevant genetic defect would potentiate the adverse effect of PAE and partially explain the variability of PAE-induced CHD incidence.

METHODS

The OFT is formed by the second heart field (SHF). Our PAE model consisted of two intraperitoneal injections (3 g/kg, separated by 6 hr) of 30% ethanol on E6.5 during SHF specification. The impact of genetic defects was studied by SHF-specific loss of Delta-like ligand 4 (Dll4), fibroblast growth factor 8 (Fgf8) and Islet1.

RESULTS

Acute PAE alone significantly increased CHD incidence (4% vs. 26%, p = .015) with a particular increase in OFT alignment defects, viz., double outlet right ventricle (0 vs. 9%, p = .02). In embryos with a SHF genetic defect, acute PAE significantly increased CHD incidence (14 vs. 63%, p < .001), including double outlet right ventricle (6 vs. 50%, p < .001) compared to controls. PAE (p = .01) and heterozygous loss of Dll4 (p = .04) were found to independently contribute to CHD incidence, while neither Islet1 nor Fgf8 defects were found to be significant.

CONCLUSIONS

Our model recapitulates the increased incidence of OFT alignment defects seen in the clinic due to PAE. The presence of a concomitant SHF genetic mutation increases the incidence of PAE-related OFT defects. An apparent synergistic interaction between PAE and the loss of DLL4-mediated Notch signaling in OFT alignment requires further analysis.

Association of Alcohol Use Diagnostic Codes in Pregnancy and Offspring Conotruncal and Endocardial Cushion Heart Defects

Background

The pathogenesis of congenital heart disease (CHD) remains largely unknown, with only a small percentage explained solely by genetic causes. Modifiable environmental risk factors, such as alcohol, are suggested to play an important role in CHD pathogenesis. We sought to evaluate the association between prenatal alcohol exposure and CHD to gain insight into which components of cardiac development may be most vulnerable to the teratogenic effects of alcohol.

Methods and Results

This was a retrospective analysis of hospital discharge records from the California Office of Statewide Health Planning and Development and linked birth certificate records restricted to singleton, live‐born infants from 2005 to 2017. Of the 5 820 961 births included, 16 953 had an alcohol‐related International Classification of Diseases, Ninth and Tenth Revisions (ICD‐9; ICD‐10) code during pregnancy. Log linear regression was used to calculate risk ratios (RR) for CHD among individuals with an alcohol‐related ICD‐9 and ICD10 code during pregnancy versus those without. Three models were created: (1) unadjusted, (2) adjusted for maternal demographic factors, and (3) adjusted for maternal demographic factors and comorbidities. Maternal alcohol‐related code was associated with an increased risk for CHD in all models (RR, 1.33 to 1.84); conotruncal (RR, 1.62 to 2.11) and endocardial cushion (RR, 2.71 to 3.59) defects were individually associated with elevated risk in all models.

Conclusions

Alcohol‐related diagnostic codes in pregnancy were associated with an increased risk of an offspring with a CHD, with a particular risk for endocardial cushion and conotruncal defects. The mechanistic basis for this phenotypic enrichment requires further investigation.

Assessing genetic counselors' graduate school education and training in congenital heart defects

Genetic counselors are one of the many providers involved in caring for patients with congenital heart defects (CHDs); however, little is known about the cardiovascular genetics training they receive by their graduate programs. To explore the recalled education experiences regarding CHDs by practicing genetic counselors, we surveyed graduates of programs primarily accredited by the American Council on Genetic Counseling (ACGC) about their graduate training in this area, the depth of CHD-specific education they received, and whether CHDs are a substantial referral indication in their current practice. Genetic counselors were recruited from the National Society of Genetic Counselors and Twitter (n = 112), and participants reflecting multiple specialties and 35 graduate programs completed an online survey which included questions about fieldwork placements and lectures in cardiovascular genetics, exposure to classification schemes regarding cardiac embryology, and education in counseling strategies for CHDs and CHD-related topics during their graduate training. When asked whether CHDs are a substantial referral indication seen in their current practice, 55% (62/112) responded yes. Most participants (79%, 88/112) recalled receiving some education about CHDs, but 91% (80/88) reported receiving little to no education regarding embryologic classification of CHDs and how to apply classification schemes to their counseling. Both participating prenatal and pediatric GCs reported that CHDs can be a common referral indication, yet they reported receiving limited education on teratogens associated with CHDs, family screening recommendations, and recurrence risk counseling for CHDs. Based on participant responses, the majority of respondents reported receiving sufficient education on syndromes with CHDs which can be beneficial in specialties such as pediatrics. This exploratory study provides insight into opportunities to further support genetic counseling educational opportunities for CHDs. These findings suggest genetic counseling graduate programs could consider implementing education on CHD counseling strategies as a standardized component of the curriculum and that practicing genetic counselors could benefit from educational opportunities and resources with updated information on this topic.

Genetic Basis of Human Congenital Heart Disease

Congenital heart disease (CHD) is the most common major congenital anomaly with an incidence of ∼1% of live births and is a significant cause of birth defect-related mortality. The genetic mechanisms underlying the development of CHD are complex and remain incompletely understood. Known genetic causes include all classes of genetic variation including chromosomal aneuploidies, copy number variants, and rare and common single-nucleotide variants, which can be either de novo or inherited. Among patients with CHD, ∼8%-12% have a chromosomal abnormality or aneuploidy, between 3% and 25% have a copy number variation, and 3%-5% have a single-gene defect in an established CHD gene with higher likelihood of identifying a genetic cause in patients with nonisolated CHD. These genetic variants disrupt or alter genes that play an important role in normal cardiac development and in some cases have pleiotropic effects on other organs. This work reviews some of the most common genetic causes of CHD as well as what is currently known about the underlying mechanisms.

Genetics in congenital heart disease. Are we ready for it?

Genetics has rightly acquired an important place in almost all medical disciplines in recent years and this is certainly the case in the field of congenital cardiology. Not only has this led to greater insight into the pathophysiology of congenital heart defects but it also has a beneficial impact on patient management. Integration of clinical genetics in multidisciplinary centers of expertise for CHD is therefore a clear recommendation. Adult and pediatric cardiologists play a crucial role in the process of genetic evaluation of patients and families and should have be familiar with red flags for referral for further clinical genetic elaboration, counseling, and eventual testing. Some basic knowledge is also important for the correct interpretation of genetic testing results. In this review article, we provide a practical overview of what genetic evaluation entails, which type of genetic tests are possible today, and how this can be used in practice for the individual patient.

Genetic considerations for adults with congenital heart disease

Congenital heart disease (CHD) remains the most common birth defect, with an estimated incidence of approximately 1% of all births. The population of adults with CHD is growing rapidly with advances in medical care. Overall survival to adulthood in the current era estimated to exceed 90%. Genetic causes of CHD can be classified into several broad categories: (a) chromosomal aneuploidy, (b) large chromosomal deletion or duplication, (c) single gene mutation, and (d) copy number variation. However, only 20-30% of CHD cases have an established etiology characterized by either genetic abnormalities or environmental factors. The role of genetics in the field of adult CHD is only increasing. More adult patients with CHD are seeking genetic counseling to understand the etiology of their underlying CHD and the risks to future offspring. A multidisciplinary approach is essential to provide appropriate counseling to patients regarding indications for genetic testing and interpretations of results. Novel advances with precision medicine may soon enable clinicians to individualize therapies for a comprehensive approach to the care of adult patients with CHD.

Associations of maternal upper respiratory tract infection/influenza during early pregnancy with congenital heart disease in offspring: evidence from a case-control study and meta-analysis

Background

Evidences regarding the associations between maternal upper respiratory tract infection/influenza during pregnancy and the risk of congenital heart disease (CHD) is still controversial. This study was specifically designed to examine the associations by a case-control study and a meta-analysis of the published evidences and our finding.

Methods

A hospital-based case-control study involving 262 children with simple CHD and 262 children with complex CHD, along with 262 control children, was conducted through June, 2016 to December, 2017. All children were aged 0–2 years old. Furthermore, a meta-analysis based on both previously published studies and our case-control study was performed.

Results

In the case-control study, after adjusting for possible confounders, maternal upper respiratory tract infection/influenza during early pregnancy was found to be related to an increased risk of CHD (OR = 3.40 and 95% CI: 2.05–5.62 for simple CHD; OR = 2.39 and 95% CI: 1.47–3.88 for complex CHD). After a meta-analysis, the adverse impact was still kept significant (OR = 1.47 and 95% CI: 1.28–1.67 for simple CHD; OR = 1.44 and 95% CI: 1.14–1.75 for complex CHD). The very similar associations were also observed among single type of CHD, herein, ventricular septal defects (VSD) and tetralogy of fallot (TOF) in the case-control study. In the subsequent meta-analysis, however, the significant association only existed in VSD.

Conclusions

Although there is still conflicting in TOF, the results are overall consistent, which provide new enforced evidence that maternal upper respiratory tract infection/influenza during early pregnancy, in general, play an important role in the occurrence of CHD.

Associations between maternal social support and stressful life event with ventricular septal defect in offspring: a case-control study

Background

Previous studies suggested that maternal subjective feeling of stress seemed to be involved in the incidence of congenial heart disease in offspring. To better understand the findings, our study would discuss the relationships of maternal exposure to stressful life event and social support, which are more objective and comprehensive indicators of stress, around periconceptional period with the risk of ventricular septal defect (VSD), the most popular subtype of congenital heart disease.

Methods

A hospital-based case-control study was conducted through June, 2016 to December, 2017. We collected maternal self-reports of 8 social support questions in 3 aspects and 8 stressful life events among mothers of 202 VSD cases and 262 controls. Social support was categorized into low, medium high, and high (higher is better), and stressful life event was indexed into low, medium low, and high (higher is worse). Logistic regression models were applied to estimate adjusted odds ratios and 95% confidence intervals (95% CI).

Results

The adjusted odds ratio of high stressful life event was 2.342 (95% CI: 1.348, 4.819) compared with low stressful life event. After crossover analysis, compared with low event & high support, the adjusted odds ratio of low event & low support, high event & high support, and high event & low support were 2.059 (95% CI: 1.104, 3.841), 2.699 (95% CI: 1.042, 6.988) and 2.781 (95% CI: 1.033, 7.489), respectively.

Conclusions

In summary, we observed an increased risk of VSD when pregnant women exposed to stressful life events, however, social support could, to some extent, reduce the risk of stressful life event.

Familial co-occurrence of congenital heart defects follows distinct patterns

Aims

Congenital heart defects (CHD) affect almost 1% of all live born children and the number of adults with CHD is increasing. In families where CHD has occurred previously, estimates of recurrence risk, and the type of recurring malformation are important for counselling and clinical decision-making, but the recurrence patterns in families are poorly understood. We aimed to determine recurrence patterns, by investigating the co-occurrences of CHD in 1163 families with known malformations, comprising 3080 individuals with clinically confirmed diagnosis.

Methods and results

We calculated rates of concordance and discordance for 41 specific types of malformations, observing a high variability in the rates of concordance and discordance. By calculating odds ratios for each of 1640 pairs of discordant lesions observed between affected family members, we were able to identify 178 pairs of malformations that co-occurred significantly more or less often than expected in families. The data show that distinct groups of cardiac malformations co-occur in families, suggesting influence from underlying developmental mechanisms. Analysis of human and mouse susceptibility genes showed that they were shared in 19% and 20% of pairs of co-occurring discordant malformations, respectively, but none of malformations that rarely co-occur, suggesting that a significant proportion of co-occurring lesions in families is caused by overlapping susceptibility genes.

Conclusion

Familial CHD follow specific patterns of recurrence, suggesting a strong influence from genetically regulated developmental mechanisms. Co-occurrence of malformations in families is caused by shared susceptibility genes.

Hypoplastic Left Heart Syndrome: A New Paradigm for an Old Disease?

Hypoplastic left heart syndrome occurs in up to 3% of all infants born with congenital heart disease and is a leading cause of death in this population. Although there is strong evidence for a genetic component, a specific genetic cause is only known in a small subset of patients, consistent with a multifactorial etiology for the syndrome. There is controversy surrounding the mechanisms underlying the syndrome, which is likely due, in part, to the phenotypic variability of the disease. The most commonly held view is that the “decreased” growth of the left ventricle is due to a decreased flow during a critical period of ventricular development. Research has also been hindered by what has been, up until now, a lack of genetically engineered animal models that faithfully reproduce the human disease. There is a growing body of evidence, nonetheless, indicating that the hypoplasia of the left ventricle is due to a primary defect in ventricular development. In this review, we discuss the evidence demonstrating that, at least for a subset of cases, the chamber hypoplasia is the consequence of hyperplasia of the contained cardiomyocytes. In this regard, hypoplastic left heart syndrome could be viewed as a neonatal form of cardiomyopathy. We also discuss the role of the endocardium in the development of the ventricular hypoplasia, which may provide a mechanistic basis for how impaired flow to the developing ventricle leads to the anatomical changes seen in the syndrome.

RNA-Seq analysis in an avian model of maternal phenylketonuria

Cardiac malformations (CVMs) are a leading cause of infant morbidity and mortality. CVMs are particularly prevalent when the developing fetus is exposed to high levels of phenylalanine in-utero in mothers with Phenylketonuria. Yet, elucidating the underlying molecular mechanism leading to CVMs has proven difficult. In this study we used RNA-Seq to investigate an avian model of MPKU and establish differential gene expression (DEG) characteristics of the early developmental stages HH10, 12, and 14. In total, we identified 633 significantly differentially expressed genes across stages HH10, 12, and 14. As expected, functional annotation of significant DEGs identified associations seen in clinical phenotypes of MPKU including CVMs, congenital heart defects, craniofacial anomalies, central nervous system defects, and growth anomalies. Additionally, there was an overrepresentation of genes involved in cardiac muscle contraction, adrenergic signaling in cardiomyocytes, migration, proliferation, metabolism, and cell survival. Strikingly, we identified significant changes in expression with multiple genes involved in Retinoic Acid (RA) metabolism and downstream targets. Using qRTPCR, we validated these findings and identified a total of 42 genes within the RA pathway that are differentially expressed. Here, we report the first elucidation of the molecular mechanisms of cardiovascular malformations in MPKU conducted at early developmental timepoints. We provide evidence suggesting a link between PHE exposure and the alteration of RA pathway. These results are promising and offer novel findings associated with congenital heart defects in MPKU.

Genetic Basis for Congenital Heart Disease: Revisited: A Scientific Statement From the American Heart Association

This review provides an updated summary of the state of our knowledge of the genetic contributions to the pathogenesis of congenital heart disease. Since 2007, when the initial American Heart Association scientific statement on the genetic basis of congenital heart disease was published, new genomic techniques have become widely available that have dramatically changed our understanding of the causes of congenital heart disease and, clinically, have allowed more accurate definition of the pathogeneses of congenital heart disease in patients of all ages and even prenatally. Information is presented on new molecular testing techniques and their application to congenital heart disease, both isolated and associated with other congenital anomalies or syndromes. Recent advances in the understanding of copy number variants, syndromes, RASopathies, and heterotaxy/ciliopathies are provided. Insights into new research with congenital heart disease models, including genetically manipulated animals such as mice, chicks, and zebrafish, as well as human induced pluripotent stem cell-based approaches are provided to allow an understanding of how future research breakthroughs for congenital heart disease are likely to happen. It is anticipated that this review will provide a large range of health care-related personnel, including pediatric cardiologists, pediatricians, adult cardiologists, thoracic surgeons, obstetricians, geneticists, genetic counselors, and other related clinicians, timely information on the genetic aspects of congenital heart disease. The objective is to provide a comprehensive basis for interdisciplinary care for those with congenital heart disease.

Genetic testing for atrioventricular septal defect

Atrioventricular septal defect (AVSD) is a congenital heart defect characterized by a shared atrioventricular junction coexisting with deficient atrioventricular septation. The main morphological characteristic of AVSD is a common atrioventricular canal. The prevalence of AVSD is estimated at 0.31/1000 live births and is higher among subjects with PTPN11 mutations. ASD may have autosomal dominant or autosomal recessive inheritance. This Utility Gene Test was prepared on the basis of an analysis of the literature and existing diagnostic protocols. It is useful for confirming diagnosis, as well as for differential diagnosis, couple risk assessment and access to clinical trials.

Down syndrome and transposition of the great arteries

There is an old adage in paediatric cardiology that, despite the high prevalence and wide spectrum of CHD, transposition of the great arteries does not occur in trisomy 21. We present a case of transposition of the great arteries, ventricular septal defect, and pulmonary stenosis in a patient with trisomy 21.

Increased regurgitant flow causes endocardial cushion defects in an avian embryonic model of congenital heart disease

BACKGROUND

The relationship between changes in endocardial cushion and resultant congenital heart diseases (CHD) has yet to be established. It has been shown that increased regurgitant flow early in embryonic heart development leads to endocardial cushion defects, but it remains unclear how abnormal endocardial cushions during the looping stages might affect the fully septated heart. The goal of this study was to reproducibly alter blood flow in vivo and then quantify the resultant effects on morphology of endocardial cushions in the looping heart and on CHDs in the septated heart.

METHODS

Optical pacing was applied to create regurgitant flow in embryonic hearts, and optical coherence tomography (OCT) was utilized to quantify regurgitation and morphology. Embryonic quail hearts were optically paced at 3 Hz (180 bpm, well above intrinsic rate 60-110 bpm) at stage 13 of development (3-4 weeks human) for 5 min. Pacing fatigued the heart and led to at least 1 h of increased regurgitant flow. Resultant morphological changes were quantified with OCT imaging at stage 19 (cardiac looping-4-5 weeks human) or stage 35 (4 chambered heart-8 weeks human).

RESULTS

All paced embryos imaged at stage 19 displayed structural changes in cardiac cushions. The amount of regurgitant flow immediately after pacing was inversely correlated with cardiac cushion size 24-h post pacing (P value < .01). The embryos with the most regurgitant flow and smallest cushions after pacing had a decreased survival rate at 8 days (P < .05), indicating that those most severe endocardial cushion defects were lethal. Of the embryos that survived to stage 35, 17/18 exhibited CHDs including valve defects, ventricular septal defects, hypoplastic ventricles, and common AV canal.

CONCLUSION

The data illustrate a strong inverse relationship in which regurgitant flow precedes abnormal and smaller cardiac cushions, resulting in the development of CHDs.

Consensus Document of the Italian Association of Hospital Cardiologists (ANMCO), Italian Society of Pediatric Cardiology (SICP), and Italian Society of Gynaecologists and Obstetrics (SIGO): pregnancy and congenital heart diseases

The success of cardiac surgery over the past 50 years has increased numbers and median age of survivors with congenital heart disease (CHD). Adults now represent two-thirds of patients with CHD; in the USA alone the number is estimated to exceed 1 million. In this population, many affected women reach reproductive age and wish to have children. While in many CHD patients pregnancy can be accomplished successfully, some special situations with complex anatomy, iatrogenic or residual pathology are associated with an increased risk of severe maternal and fetal complications. Pre-conception counselling allows women to come to truly informed choices. Risk stratification tools can also help high-risk women to eventually renounce to pregnancy and to adopt safe contraception options. Once pregnant, women identified as intermediate or high risk should receive multidisciplinary care involving a cardiologist, an obstetrician and an anesthesiologist with specific expertise in managing this peculiar medical challenge. This document is intended to provide cardiologists working in hospitals where an Obstetrics and Gynecology Department is available with a streamlined and practical tool, useful for them to select the best management strategies to deal with a woman affected by CHD who desires to plan pregnancy or is already pregnant.

The Current Landscape of Genetic Testing in Cardiovascular Malformations: Opportunities and Challenges

Human cardiovascular malformations (CVMs) frequently have a genetic contribution. Through the application of novel technologies, such as next-generation sequencing, DNA sequence variants associated with CVMs are being identified at a rapid pace. While clinicians are now able to offer testing with NGS gene panels or whole exome sequencing to any patient with a CVM, the interpretation of genetic variation remains problematic. Variable phenotypic expression, reduced penetrance, inconsistent phenotyping methods, and the lack of high-throughput functional testing of variants contribute to these challenges. This article elaborates critical issues that impact the decision to broadly implement clinical molecular genetic testing in CVMs. Major benefits of testing include establishing a genetic diagnosis, facilitating cost-effective screening of family members who may have subclinical disease, predicting recurrence risk in offsprings, enabling early diagnosis and anticipatory management of CV and non-CV disease phenotypes, predicting long-term outcomes, and facilitating the development of novel therapies aimed at disease improvement or prevention. Limitations include financial cost, psychosocial cost, and ambiguity of interpretation of results. Multiplex families and patients with syndromic features are two groups where disease causation could potentially be firmly established. However, these account for the minority of the overall CVM population, and there is increasing recognition that genotypes previously associated with syndromes also exist in patients who lack non-CV findings. In all circumstances, ongoing dialog between cardiologists and clinical geneticists will be needed to accurately interpret genetic testing and improve these patients’ health. This may be most effectively implemented by the creation and support of CV genetics services at centers committed to pursuing testing for patients.

Down syndrome-A narrative review with a focus on anatomical features

Down syndrome (DS) is the most common aneuploidy of chromosome 21, characterized by the presence of an extra copy of that chromosome (trisomy 21). Children with DS present with an abnormal phenotype, which is attributed to a loss of genetic balance or an excess dose of chromosome 21 genes. In recent years, advances in prenatal screening and diagnostic tests have aided in the early diagnosis and appropriate management of fetuses with DS. A myriad of clinical symptoms resulting from cognitive, physical, and physiological impairments caused by aberrations in various systems of the body occur in DS. However, despite these impairments, which range from trivial to fatal manifestations, the survival rate of individuals with DS has increased dramatically from less than 50% during the mid-1990s to 95% in the early 2000s, with a median life expectancy of 60 years reported recently. The aim of this narrative review is to review and summarize the etiopathology, prenatal screening and diagnostic tests, prognosis, clinical manifestations in various body systems, and comorbidities associated with DS. Clin. Anat. 29:568-577, 2016. © 2015 Wiley Periodicals, Inc.

Genetic Evaluation and Use of Chromosome Microarray in Patients with Isolated Heart Defects: Benefits and Challenges of a New Model in Cardiovascular Care

Congenital heart defects (CHDs) are common birth defects and result in significant morbidity and global economic impact. Genetic factors play a role in most CHDs; however, identification of these factors has been historically slow due to technological limitations and incomplete understanding of the impact of human genomic variation on normal and abnormal cardiovascular development. The advent of chromosome microarray (CMA) brought tremendous gains in identifying chromosome abnormalities in a variety of human disorders and is now considered part of a standard evaluation for individuals with multiple congenital anomalies and/or neurodevelopmental disorders. Several studies investigating use of CMA found that this technology can identify pathogenic copy-number variations (CNVs) in up to 15-20% of patients with CHDs with other congenital anomalies. However, there have been fewer studies exploring the use of CMA for patients with isolated CHDs. Recent studies have shown that the diagnostic yield of CMA in individuals with seemingly isolated CHD is lower than in individuals with CHDs and additional anomalies. Nevertheless, positive CMA testing in this group supports chromosome variation as one mechanism underlying the development of isolated, non-syndromic CHD - either as a causative or risk-influencing genetic factor. CMA has also identified novel genomic variation in CHDs, shedding light on candidate genes and pathways involved in cardiac development and malformations. Additional studies are needed to further address this issue. Early genetic diagnosis can enhance the medical management of patients and potentially provide crucial information about recurrence. This information is critical for genetic counseling of patients and family members. In this review, we review CMA for the non-genetics cardiology provider, offer a summary of CNV in isolated CHDs, and advocate for the use of CMA as part of the cardiovascular genetics evaluation of patients with isolated CHDs. We also provide perspective regarding the benefits and challenges that lie ahead for this model in the clinical setting.

Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes as a Model for Heart Development and Congenital Heart Disease

Congenital heart disease (CHD) remains a significant health problem, with a growing population of survivors with chronic disease. Despite intense efforts to understand the genetic basis of CHD in humans, the etiology of most CHD is unknown. Furthermore, new models of CHD are required to better understand the development of CHD and to explore novel therapies for this patient population. In this review, we highlight the role that human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes can serve to enhance our understanding of the development, pathophysiology and potential therapeutic targets for CHD. We highlight the use of hiPSC-derived cardiomyocytes to model gene regulatory interactions, cell-cell interactions and tissue interactions contributing to CHD. We further emphasize the importance of using hiPSC-derived cardiomyocytes as personalized research models. The use of hiPSCs presents an unprecedented opportunity to generate disease-specific cellular models, investigate the underlying molecular mechanisms of disease and uncover new therapeutic targets for CHD.

Genetic and Developmental Basis of Cardiovascular Malformations

Cardiovascular malformations (CVMs) are the most common birth defect, occurring in 1% to 5% of all live births. Genetic, epigenetic, and environmental factors all influence the development of CVMs, and an improved understanding of the causation of CVMs is a prerequisite for prevention. Cardiac development is a complex, multistep process of morphogenesis that is under genetic regulation. Although the genetic contribution to CVMs is well recognized, the genetic causes of human CVMs are still identified infrequently. This article discusses the key genetic concepts characterizing human CVMs, their developmental basis, and the critical developmental and genetic concepts underlying their pathogenesis.

Genetics and genetic testing in congenital heart disease

Congenital heart defects (CHDs) are structural abnormalities of the heart and great vessels that are present from birth. The presence or absence of extracardiac anomalies has historically been used to identify patients with possible monogenic, chromosomal, or teratogenic CHD causes. These distinctions remain clinically relevant, but it is increasingly clear that nonsyndromic CHDs can also be genetic. This article discusses key morphologic, molecular, and signaling mechanisms relevant to heart development, summarizes overall progress in molecular genetic analyses of CHDs, and provides current recommendations for clinical application of genetic testing.

Rationale for the Cytogenomics of Cardiovascular Malformations Consortium: A Phenotype Intensive Registry Based Approach

Cardiovascular malformations (CVMs) are the most common birth defect, occurring in 1%–5% of all live births. Although the genetic contribution to CVMs is well recognized, the genetic causes of human CVMs are identified infrequently. In addition, a failure of systematic deep phenotyping of CVMs, resulting from the complexity and heterogeneity of malformations, has obscured genotype-phenotype correlations and contributed to a lack of understanding of disease mechanisms. To address these knowledge gaps, we have developed the Cytogenomics of Cardiovascular Malformations (CCVM) Consortium, a multi-site alliance of geneticists and cardiologists, contributing to a database registry of submicroscopic genetic copy number variants (CNVs) based on clinical chromosome microarray testing in individuals with CVMs using detailed classification schemes. Cardiac classification is performed using a modification to the National Birth Defects Prevention Study approach, and non-cardiac diagnoses are captured through ICD-9 and ICD-10 codes. By combining a comprehensive approach to clinically relevant genetic analyses with precise phenotyping, the Consortium goal is to identify novel genomic regions that cause or increase susceptibility to CVMs and to correlate the findings with clinical phenotype. This registry will provide critical insights into genetic architecture, facilitate genotype-phenotype correlations, and provide a valuable resource for the medical community.

December 2014 HeartWeek issue of cardiology in the young: highlights of HeartWeek 2014: diseases of the cardiac valves from the foetus to the adult

This December Issue of Cardiology in the Young represents the 12th annual publication generated from the two meetings that compose "HeartWeek in Florida". "HeartWeek in Florida", the joint collaborative project sponsored by the Cardiac Center at the Children's Hospital of Philadelphia, Pennsylvania, together with Johns Hopkins All Children's Heart Institute of Saint Petersburg, Florida, averages over 1000 attendees every year and is now recognised as one of the major planks of continuing medical and nursing education for those working in the fields of diagnosis and treatment of cardiac disease in the foetus, neonate, infant, child, and adult. "HeartWeek in Florida" combines the International Symposium on Congenital Heart Disease, organised by All Children's Hospital and Johns Hopkins Medicine and entering its 15th year, with the Annual Postgraduate Course in Pediatric Cardiovascular Disease, organised by The Children's Hospital of Philadelphia and entering its 18th year. This December, 2014 Issue of Cardiology in the Young features highlights of Johns Hopkins All Children's Heart Institute's 14th Annual International Symposium on Congenital Heart Disease, which was held at the Renaissance Vinoy Resort & Golf Club, Saint Petersburg, Florida, from 15-18 February, 2014. This Symposium was co-sponsored by The American Association for Thoracic Surgery (AATS) and had as its special focus " Diseases of the Cardiac Valves from the Fetus to the Adult ". We acknowledge the tremendous contributions made to paediatric and congenital cardiac care by Duke Cameron and Joel Brenner, and therefore we dedicate this December, 2014 HeartWeek Issue of Cardiology in the Young to them. Duke Cameron is Professor of Surgery at Johns Hopkins University and Cardiac Surgeon-in-Charge at The Johns Hopkins Hospital. Joel Brenner is Professor of Pediatrics at Johns Hopkins University and Director of the Taussig Heart Center at Bloomberg Children's Center, The Johns Hopkins Hospital. Together, Joel and Duke lead the proud paediatric and congenital cardiac programme at The Johns Hopkins Hospital.

Case-control analysis of maternal prenatal analgesic use and cardiovascular malformations: Baltimore-Washington Infant Study

OBJECTIVE

We sought to assess maternal prenatal use of analgesics and risk of cardiovascular malformations (CVM) in the offspring.

STUDY DESIGN

Data from the Baltimore-Washington Infant Study, a population-based case-control investigation of CVM, were used to examine selected isolated CVM diagnoses and maternal analgesic use during the periconceptional period (3 months before and after conception). We compared case and control infants on frequency of maternal use of analgesics and estimated adjusted odds ratios (adjORs) and 95% confidence intervals (CI) with logistic regression models for specific CVM phenotypes.

RESULTS

Frequency of periconceptional use of any analgesic was 52% among control mothers and 53% among case mothers. Analyses by CVM diagnoses identified an association of tetralogy of Fallot with maternal acetaminophen use (adjOR, 1.6; 95% CI, 1.1-2.3) and dextrotransposition of the great arteries with intact ventricular septum with maternal nonsteroidal antiinflammatory drug use (adjOR, 3.2; 95% CI, 1.2-8.7).

CONCLUSION

Analgesic use during the periconceptional period was not associated with CVM in the aggregate or with most phenotypes of CVM examined. Associations with 2 phenotypes of CVM may have occurred by chance. These findings warrant corroboration and further study, including further evaluation of the observed associations, the dose of analgesic taken, more specific timing of analgesic use, and indications for use.

Insights into the genetic structure of congenital heart disease from human and murine studies on monogenic disorders

Study of monogenic congenital heart disease (CHD) has provided entry points to gain new understanding of heart development and the molecular pathogenesis of CHD. In this review, we discuss monogenic CHD caused by mutations of the cardiac transcription factor genes NKX2-5 and GATA4. Detailed investigation of these genes in mice and humans has expanded our understanding of heart development, shedding light on the complex genetic and environmental factors that influence expression and penetrance of CHD gene mutations.

Prevalence of associated extracardiac malformations in the congenital heart disease population

The authors hypothesized that changes in prenatal factors such as termination of pregnancy for fetal anomalies and prenatal vitamin supplementation have altered the epidemiology of patients with multiple congenital anomalies and may have had an impact on their prevalence in the current era. This study reviewed the Nationwide Inpatient Sample database from 1998 to 2008 and compared the prevalence of ECM among live births with a CHD diagnosis (case) and that among live births without a CHD diagnosis (control). For this study, 42 ECM and 10 CHD diagnoses were selected for subanalysis. Longitudinal analysis also was performed to determine temporal variation of ECM prevalence in the CHD population during the 11-year study period. The cohort in this study consisted of 97,154 patients in the case group and 12,078,482 subjects in the control group. The prevalences in the CHD population were 11.4 % for nonsyndromic congenital malformation (NSCM), 2.2 % for genetic syndrome (GS), and 13.6 % for overall extracardiac congenital malformation (ECM). The prevalences in the control group were 6.7 % for NSCM, 0.3 % for GS, and 7.0 % for ECM. The findings showed a strong association of NSCM [odds ratio (OR) 1.88; 95 % confidence interval (CI) 1.73-1.94], GS (OR 2.52; 95 % CI 2.44-2.61), and overall ECM (OR 2.01; 95 % CI 1.97-2.14) with CHD. The prevalences of GS and multiple organ system CM decreased significantly during the study period. This study was the largest and most comprehensive population-based study to evaluate the association between CHD and ECM in newborns.

Prevalence of congenital anomalies in newborns with congenital heart disease diagnosis

BACKGROUND

There is a known association between congenital heart disease (CHD) and other congenital anomalies (CA). These associations have been altered by changes in prenatal factors in recent time. We reviewed the largest database of inpatient hospitalization information and analyzed the current association between common CHD diagnoses and other congenital anomalies.

MATERIALS AND METHODS

Case-control study design. We reviewed the Nationwide Inpatient Sample (NIS) database from 1998 to 2008 and identified all live births with CHD diagnosis (case) and live births without CHD diagnosis (control). We compared prevalence of associated congenital anomalies between the case and control groups.

RESULTS

Our cohort consisted of 97,154 and 12,078,482 subjects in the case and control groups, respectively. In the CHD population, prevalence of non-syndromic congenital anomaly (NSCA), genetic syndrome (GS), and overall extra-cardiac congenital anomaly (CA) were 11.4, 2.2, and 13.6%, respectively. In the control group, prevalence of NSCA, GS, and CA were 6.7, 0.3, and 7.0%, respectively. NSCA (odds ratio (OR): 1.88, confidence interval (CI): 1.73-1.94), GS (OR 2.52, CI 2.44-2.61), and overall CA (OR: 2.01, CI: 1.97-2.14) were strongly associated with CHD. Prevalence of GS and multiple organ-system CA decreased significantly over the study period.

CONCLUSIONS

This is the largest and most comprehensive population-based study evaluating association between CHD and extra-cardiac malformation (ECM) in newborns. There was significant decrease in prevalence of GS and multiple CA over the study period.

Genetic basis of congenital cardiovascular malformations

Cardiovascular malformations are a singularly important class of birth defects and due to dramatic improvements in medical and surgical care, there are now large numbers of adult survivors. The etiologies are complex, but there is strong evidence that genetic factors play a crucial role. Over the last 15 years there has been enormous progress in the discovery of causative genes for syndromic heart malformations and in rare families with Mendelian forms. The rapid characterization of genomic disorders as major contributors to congenital heart defects is also notable. The genes identified encode many transcription factors, chromatin regulators, growth factors and signal transduction proteins- all unified by their required roles in normal cardiac development. Genome-wide sequencing of the coding regions promises to elucidate genetic causation in several disorders affecting cardiac development. Such comprehensive studies evaluating both common and rare variants would be essential in characterizing gene-gene interactions, as well as in understanding the gene-environment interactions that increase susceptibility to congenital heart defects.

Rare variants in NR2F2 cause congenital heart defects in humans

Congenital heart defects (CHDs) are the most common birth defect worldwide and are a leading cause of neonatal mortality. Nonsyndromic atrioventricular septal defects (AVSDs) are an important subtype of CHDs for which the genetic architecture is poorly understood. We performed exome sequencing in 13 parent-offspring trios and 112 unrelated individuals with nonsyndromic AVSDs and identified five rare missense variants (two of which arose de novo) in the highly conserved gene NR2F2, a very significant enrichment (p = 7.7 × 10(-7)) compared to 5,194 control subjects. We identified three additional CHD-affected families with other variants in NR2F2 including a de novo balanced chromosomal translocation, a de novo substitution disrupting a splice donor site, and a 3 bp duplication that cosegregated in a multiplex family. NR2F2 encodes a pleiotropic developmental transcription factor, and decreased dosage of NR2F2 in mice has been shown to result in abnormal development of atrioventricular septa. Via luciferase assays, we showed that all six coding sequence variants observed in individuals significantly alter the activity of NR2F2 on target promoters.

Detection of submicroscopic chromosomal aberrations by array-based comparative genomic hybridization in fetuses with congenital heart disease

OBJECTIVES

To evaluate the usefulness of array-based comparative genomic hybridization (aCGH) for prenatal genetic diagnosis of congenital heart disease (CHD), with and without associated anomalies, and to explore the relationship between submicroscopic chromosomal aberrations and CHD.

METHODS

In this prospective study we investigated 76 consecutive singleton fetuses with abnormal cardiac ultrasound findings, normal karyotype and negative or no fluorescence in-situ hybridization results for 22q11.2 deletion syndrome. All pregnancies underwent aCGH in a comprehensive search for chromosomal aberrations. The relationship between copy number variations (CNVs) and CHD was determined by comparing clinical findings to chromosomal databases.

RESULTS

CNVs that were benign or had no clinical significance were detected in 18/76 (23.7%) cases. CNVs of unknown clinical significance (i.e. VOUS) were detected in 4/76 (5.3%) cases. Pathogenic CNVs were detected in 5/76 (6.6%) cases. Fetuses with CHD and additional structural abnormalities demonstrated no difference in number of pathogenic CNVs when compared with fetuses with isolated CHD (7.4% (n = 2/27) vs 6.1% (n = 3/49), P > 0.05).

CONCLUSION

In this study cohort, aCGH analysis significantly improved the detection of submicroscopic chromosomal aberrations in pregnancies with CHD, as compared with conventional cytogenetics. Our results suggest that aCGH can provide additional genetic information in fetuses with abnormal heart findings.

Genetic abnormalities in FOXP1 are associated with congenital heart defects

The etiology for the majority of congenital heart defects (CHD) is unknown. We identified a patient with unbalanced atrioventricular septal defect (AVSD) and hypoplastic left ventricle who harbored an ~0.3 Mb monoallelic deletion on chromosome 3p14.1. The deletion encompassed the first four exons of FOXP1, a gene critical for normal heart development that represses cardiomyocyte proliferation and expression of Nkx2.5. To determine whether FOXP1 mutations are found in patients with CHD, we sequenced FOXP1 in 82 patients with AVSD or hypoplastic left heart syndrome. We discovered two patients who harbored a heterozygous c.1702C>T variant in FOXP1 that predicted a potentially deleterious substitution of a highly conserved proline (p.Pro568Ser). This variant was not found in 287 controls but is present in dbSNP at a 0.2% frequency. The orthologous murine Foxp1 p.Pro596Ser mutant protein displayed deficits in luciferase reporter assays and resulted in increased proliferation and Nkx2.5 expression in cardiomyoblasts. Our data suggest that haploinsufficiency of FOXP1 is associated with human CHD.

Cardiac teratogenicity in mouse maternal phenylketonuria: defining phenotype parameters and genetic background influences

Maternal phenylketonuria (MPKU) is a syndrome including cardiovascular malformations (CVMs), microcephaly, intellectual impairment, and small size for gestational age, caused by in-utero exposure to elevated serum phenylalanine (Phe) due to PKU in the mother. It is becoming a public health concern as more women with PKU reach child bearing age. Although a mouse model of PKU, BTBR Pah(enu2), has been available for 20 years, it has not been well utilized for studying MPKU. We used this model to delineate critical parameters in Phe cardiovascular teratogenicity and study the effect of genetic background. Dosing and timing experiments were performed with the BTBR Pah(enu2) mouse. A dose response curve was noted, with CVM rates at maternal serum Phe levels <360 μM (control), 360-600 μM (low), 600-900 μM (mid), and >900 μM (high) of 11.86%, 16.67%, 30.86%, and 46.67% respectively. A variety of CVMs were noted on the BTBR background, including double outlet right ventricle (DORV), aortic arch artery (AAA) abnormalities, and ventricular septal defects (VSDs). Timed exposure experiments identified a teratogenic window from embryonic day 8.5-13.5, with higher rates of conotruncal and valve defects occurring in early exposure time and persistent truncus arteriosus (PTA) and aortic arch branching abnormalities occurring with late exposure. Compared to the BTBR strain, N10+ Pah(enu2) congenics on the C3H/HeJ background had higher rates of CVMs in general and propensity to left ventricular outflow tract (LVOT) malformations, while the C57B/L6 background had similar CVM rates but predominately AAA abnormalities. We have delineated key parameters of Phe cardiovascular teratogenicity, demonstrated the utility of this MPKU model on different mouse strains, and shown how genetic background profoundly affects the phenotype.

Functional significance of SRJ domain mutations in CITED2

CITED2 is a transcriptional co-activator with 3 conserved domains shared with other CITED family members and a unique Serine-Glycine Rich Junction (SRJ) that is highly conserved in placental mammals. Loss of Cited2 in mice results in cardiac and aortic arch malformations, adrenal agenesis, neural tube and placental defects, and partially penetrant defects in left-right patterning. By screening 1126 sporadic congenital heart disease (CHD) cases and 1227 controls, we identified 19 variants, including 5 unique non-synonymous sequence variations (N62S, R92G, T166N, G180-A187del and A187T) in patients. Many of the CHD-specific variants identified in this and previous studies cluster in the SRJ domain. Transient transfection experiments show that T166N mutation impairs TFAP2 co-activation function and ES cell proliferation. We find that CITED2 is phosphorylated by MAPK1 in vitro at T166, and that MAPK1 activation enhances the coactivation function of CITED2 but not of CITED2-T166N. In order to investigate the functional significance in vivo, we generated a T166N mutation of mouse Cited2. We also used PhiC31 integrase-mediated cassette exchange to generate a Cited2 knock-in allele replacing the mouse Cited2 coding sequence with human CITED2 and with a mutant form deleting the entire SRJ domain. Mouse embryos expressing only CITED2-T166N or CITED2-SRJ-deleted alleles surprisingly show no morphological abnormalities, and mice are viable and fertile. These results indicate that the SRJ domain is dispensable for these functions of CITED2 in mice and that mutations clustering in the SRJ region are unlikely to be the sole cause of the malformations observed in patients with sporadic CHD. Our results also suggest that coding sequence mutations observed in case-control studies need validation using in vivo models and that predictions based on structural conservation and in vitro functional assays, or even in vivo global loss of function models, may be insufficient.

Rare DNA copy number variants in cardiovascular malformations with extracardiac abnormalities

Clinically significant cardiovascular malformations (CVMs) occur in 5-8 per 1000 live births. Recurrent copy number variations (CNVs) are among the known causes of syndromic CVMs, accounting for an important fraction of cases. We hypothesized that many additional rare CNVs also cause CVMs and can be detected in patients with CVMs plus extracardiac anomalies (ECAs). Through a genome-wide survey of 203 subjects with CVMs and ECAs, we identified 55 CNVs >50 kb in length that were not present in children without known cardiovascular defects (n=872). Sixteen unique CNVs overlapping these variants were found in an independent CVM plus ECA cohort (n=511), which were not observed in 2011 controls. The study identified 12/16 (75%) novel loci including non-recurrent de novo 16q24.3 loss (4/714) and de novo 2q31.3q32.1 loss encompassing PPP1R1C and PDE1A (2/714). The study also narrowed critical intervals in three well-recognized genomic disorders of CVM, such as the cat-eye syndrome region on 22q11.1, 8p23.1 loss encompassing GATA4 and SOX7 and 17p13.3-p13.2 loss. An analysis of protein-interaction databases shows that the rare inherited and de novo CNVs detected in the combined cohort are enriched for genes encoding proteins that are direct or indirect partners of proteins known to be required for normal cardiac development. Our findings implicate rare variants such as 16q24.3 loss and 2q31.3-q32.1 loss, and delineate regions within previously reported structural variants known to cause CVMs.

The Role of the Geneticist and Genetic Counselor in an ACHD Clinic

There is a growing population of adults with congenital heart disease due to the advancements in surgical repair and medical management. At the same time, the understanding of the genetic basis of both syndromic and isolated congenital heart disease has grown tremendously and is being rapidly translated into changes in clinical care, resulting in an increasing need for incorporation of genetic expertise into the care of adult congenital heart disease patients. Here we review the importance of delivery of genetic information to the adult congenital heart disease population and highlight the shared and distinct roles of clinical geneticists and genetic counselors in provision of services. The adult congenital heart disease patient population has unique needs and clinical geneticists and genetic counselors can play an important role in the diagnostic evaluation and assessment of these patients to provide an accurate etiologic diagnosis and to counsel regarding genetic testing, recurrence risk, family screening, and prenatal diagnosis.

Genetic modifiers predisposing to congenital heart disease in the sensitized Down syndrome population

BACKGROUND

About half of people with Down syndrome (DS) exhibit some form of congenital heart disease (CHD); however, trisomy for human chromosome 21 (Hsa21) alone is insufficient to cause CHD, as half of all people with DS have a normal heart, suggesting that genetic modifiers interact with dosage-sensitive gene(s) on Hsa21 to result in CHD. We hypothesize that a threshold exists in both DS and euploid populations for the number of genetic perturbations that can be tolerated before CHD results.

METHODS AND RESULTS

We ascertained a group of individuals with DS and complete atrioventricular septal defect and sequenced 2 candidate genes for CHD: CRELD1, which is associated with atrioventricular septal defect in people with or without DS, and HEY2, whose mouse ortholog (Hey2) produces septal defects when mutated. Several deleterious variants were identified, but the frequency of these potential modifiers was low. We crossed mice with mutant forms of these potential modifiers to the Ts65Dn mouse model of DS. Crossing loss-of-function alleles of either Creld1 or Hey2 onto the trisomic background caused a significant increase in the frequency of CHD, demonstrating an interaction between the modifiers and trisomic genes. We showed further that, although each of these mutant modifiers is benign by itself, they interact to affect heart development when inherited together.

CONCLUSIONS

Using mouse models of Down syndrome and of genes associated with congenital heart disease, we demonstrate a biological basis for an interaction that supports a threshold hypothesis for additive effects of genetic modifiers in the sensitized trisomic population.

Recurrence of congenital heart disease in cases with familial risk screened prenatally by echocardiography

Objectives. To evaluate the recurrence of congenital heart disease (CHD) in pregnant women with familial risk who had been referred for fetal echocardiography. Material and Methods. 1634 pregnancies from 1483 women with familial history of CHD in one or more relatives were studied. Fetal cardiologic diagnosis was compared with postnatal findings at 6 months or at autopsy. Results. Total recurrence rate of CHD was 3.98%, 4.06% in single familial risk, 2.9% in double, and 5% in multiple risk. It was 3.5% in case of one previously affected child; 4.5% with 2 children; 5.2% with the mother alone affected and 7,5% with father alone affected and 3.5% with a single distant relative. Exact concordance of CHD was found in 21.5% and a partial concordance in 20% of cases. Conclusions. Our data show a higher recurrence rate of CHD than previously published data and high relative risk ratios compared to normal population.

Prenatally detectable congenital heart defects in fetuses with Down syndrome

OBJECTIVE

To document the incidence of congenital heart defects (CHD) that are detectable echocardiographically in the fetus with trisomy 21 and the relationship with nuchal translucency, fetal sex and ethnicity.

METHODS

Data on fetuses with a karyotypic diagnosis of trisomy 21 were collected between January 2002 and March 2010. The data were analyzed for the gestational age at examination, maternal age, reason for referral for fetal echocardiography, cardiac diagnosis, fetal sex, ethnicity and outcome.

RESULTS

Of 917 fetuses with trisomy 21, 487 had a diagnostic echocardiogram. Cardiac examination was performed before 14 weeks' gestation in 75% of cases. The main reasons for referral were increased nuchal translucency (NT) in 76% of cases, suspected cardiac abnormality in 15% and an extracardiac anomaly in 6%. Structural CHD was found in 164/487 (34%), or 98/412 (24%) if those referred for suspected CHD are removed from the analysis. The most common diagnosis was atrioventricular septal defect (AVSD) (115/487, 24%). The ratio of female to male fetuses with AVSD was 29%:18% (P = 0.003). There was no difference in the incidence of AVSD with ethnicity. The pregnancy continued in 36 cases, but three were lost to follow-up; of the known outcomes there were 10 intrauterine deaths, six of which had structural heart disease, and 23 live births, 15 of which had CHD.

CONCLUSION

Most fetuses (66-76%) with trisomy 21 have a structurally normal heart on echocardiography. The presence of structural CHD was not associated with increased NT. The increased incidence of AVSD in females was confirmed in our study, although an ethnic difference could not be confirmed. CHD does not appear to increase the chance of spontaneous intrauterine loss in ongoing pregnancies.

Congenital heart defects and major structural noncardiac anomalies, Atlanta, Georgia, 1968 to 2005

OBJECTIVE

To identify the proportion of major structural noncardiac anomalies identified with congenital heart defects (CHDs).

STUDY DESIGN

Records of infants with CHDs in the Metropolitan Atlanta Congenital Defects Program who were born during the period 1968 through 2005 were classified as having isolated, syndromic, multiple CHD (ie, having an unrecognized pattern of multiple congenital anomalies or a recognized pattern of multiple congenital anomalies of unknown etiology), or laterality defects. Frequencies of associated noncardiac anomalies were obtained.

RESULTS

We identified 7984 live-born and stillborn infants and fetuses with CHDs. Among them, 5695 (71.3%) had isolated, 1080 (13.5%) had multiple, 1048 (13.1%) had syndromic, and 161 (2.0%) had laterality defects. The percentage of multiple congenital anomalies was highest for case with atrial septal defects (18.5%), cardiac looping defects (17.2%), and conotruncal defects (16.0%), and cases with atrioventricular septal defects represented the highest percentages of those with syndromic CHDs (66.7%).

CONCLUSIONS

Including those with syndromes and laterality defects, 28.7% of case infants with CHDs had associated major noncardiac malformations. Thus, infants with CHDs warrant careful examination for the presence of noncardiac anomalies.

Perioperative management of low birth weight infants for open-heart surgery

Infants of birth weight ≤2500 g are termed low birth weight (LBW). These children often have considerable morbidity from prematurity and intra-uterine growth restriction. Additionally, LBW infants have increased risk for cardiac and noncardiac congenital anomalies and may require surgery. Primary rather than palliative surgical repair of cardiac lesions has been preferred in recent years. However, LBW remains a risk factor for increased mortality and morbidity after open-heart surgery (OHS). There is a paucity of information about the anesthetic challenges presented by LBW infants undergoing OHS. This review summarizes the perioperative issues of relevance to anesthesiologists who manage these high-risk patients. Emphasis is placed on management concerns that are unique to LBW infants. Retrospective data from the authors' institution are provided for those aspects of anesthetic care that lack published studies. Successful outcome often requires substantial hospital resources and collaborative multi-disciplinary effort.

Perspectives on the potential involvement of the AH receptor-dioxin axis in cardiovascular disease

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that mediates the induction of the CYP1 family of cytochrome P450s and of several phase II detoxification enzymes. Although induction of these genes is the best characterized AHR function, it does not adequately explain the diversity of AHR-mediated effects. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the prototypical AHR ligand and dioxin congener and a model for many environmentally relevant organochlorinated compounds. Research over the course of the last 30 years has made it evident that AHR activation in response to TCDD and other xenobiotic agonists directly affects multiple metabolic pathways, leading to the identification of many AHR-directed effects of dioxin involved in regulation of growth factor signaling, cell cycle proliferation, differentiation, arrest, and apoptosis. There is ample evidence that TCDD causes persistent cardiac defects in zebrafish, chickens, mice, and likely humans and is associated with human cardiovascular disease. The question that I address here is whether exposure to TCDD during early development perturbs the concerted differentiation patterns of cardiovascular cell lineages and tissues and leads to cardiac malformations and long-term cardiovascular disease. Research to define the mechanisms responsible for the lifelong cardiovascular malformations resulting from TCDD exposure during embryonic development will be highly significant to the prevention of environmental cardiovascular injury.

Novel CRELD1 gene mutations in patients with atrioventricular septal defect

BACKGROUND

Atrioventricular septal defects (AVSDs) occur as clinical defects of several different syndromes, as autosomal dominant defects, and as sporadically occurring malformations. Consequently, there is genetic heterogeneity, but until recently, little is known about the genes involving in the pathogenesis of AVSD. CRELD1 gene, a novel cell adhesion molecule, is a candidate gene for AVSD.

METHODS

This study included 133 patients with AVSD and 200 healthy controls. Peripheral blood samples were collected and genomic DNA was extracted from the leukocytes. CRELD1 was amplified by polymerase chain reaction (PCR) with specific primers. The sequences of PCR products were compared between the patients and controls.

RESULTS

In a patient, a C-to-G transition was identified at nucleotide 857 in exon 8 that resulted in a substitution of alanine for proline at amino acid 286 in the first calcium-binding EGF domain. This patient had an isolated partial AVSD and the mutation was inherited from her mother. Another mutation was detected in a patient with a partial AVSD and evidence of Down syndrome. The heterozygous c.973G>A transition in exon 9 resulted in a substitution of lysine for glutamic acid at amino acid 325 (E325K) in the second calcium-binding EGF domain.

CONCLUSIONS

Two novel CRELD1 mutations were identified in the calcium-binding EGF domain in patients with AVSD. CRELD1 is likely to be an AVSD-susceptibility gene and CRELD1 mutations may increase the risk of developing a heart defect rather than being a direct causative mutation.