Genetics of Congenital Heart Disease: Past and Present

Chylothorax: a rare postoperative complication in paediatric cardiac surgery patients - a 15-year retrospective study from a tertiary care centre in a developing country

Chylothorax, a postoperative complication of CHD surgery, involves chyle accumulation in the pleural cavity, posing challenges in diagnosis and management. This retrospective study investigates the prevalence, aetiology, management, and outcomes of postoperative chylothorax in paediatric patients undergoing cardiac corrective surgery at a tertiary care centre over 15 years. Medical records of paediatric patients who underwent cardiothoracic surgery at the Children's Heart Center at the American University of Beirut Medical Center between 2007 and 2022 were retrospectively reviewed. Data collection included demographic characteristics, blood parameters, chylous fluid characteristics, diagnostic criteria, treatment modalities, and hospitalisation details. Ethical approval was obtained, and descriptive statistics were employed using SAS 9.4. Among 2,997 children who underwent cardiothoracic surgery, nineteen cases of postoperative chylothorax were identified. The majority were females (63.2%) with a median age of 9 months. Glenn, Fontan, and Blalock-Taussig shunt-related surgeries were the most common operations associated with chylothorax. Single ventricle physiology was the predominant CHD observed (58%). Diagnosis relied primarily on clinical presentation, imaging studies, and triglyceride levels in pleural fluid. Treatment options included conservative dietary modifications, medical therapy such as octreotide, and surgical intervention if necessary. No mortalities were reported, and patients were adequately followed up. This study sheds light on postoperative chylothorax in paediatric cardiac patients, offering insights into its epidemiology, aetiology, clinical features, and treatment outcomes. While conservative and medical approaches effectively managed chylothorax in this group, larger studies are needed to develop standardised diagnostic and treatment protocols, improving outcomes in paediatric patients with postoperative chylothorax.

Association Study of MTHFR C677T Polymorphism With Homocysteine Level and Coronary Heart Disease in Elderly Patients

Objective: To investigate the relationship between methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism and coronary heart disease (CHD) in the elderly patients living in the coastal area of eastern Zhejiang Province in China. Methods: From September 2021 to May 2022, 163 elderly patients (male ≥ 55 years old, female ≥ 65 years old) admitted to the cardiology department in the Ningbo Lihuili Hospital were collected. Among these patients, 90 patients were diagnosed with CHD (CHD group) and 79 patients did not have CHD (control group). The homocysteine (Hcy) level was measured by the blood biochemical test, and the MTHFR genotype was detected by the PCR fluorescence probe method. Results: Compared with the control group, the CHD group showed a significantly higher distribution frequency of TT genotype (X 2 = 5.137, p < 0.05) and a lower frequency of CC genotype (X 2 = 6.560, p < 0.05), indicating that elderly people with MTHFR677 TT genotype are more likely to have CHD. In addition, the Hcy level of TT genotype in the CHD group and the control group were both obviously higher than that of CT genotype and CC genotype (p < 0.05). Finally, the univariate and multivariate logistic regression analyses showed that gender, hypertension, diabetes, and MTHFR677 TT genotype were independent risk factors for CHD (p < 0.05). Conclusion: MTHFR C677T mutation is significantly associated with the serum Hcy, and is an important genetic risk for CHD development in the elderly people living in the coastal area of eastern Zhejiang province, China.

Impact of MTHFR Gene Polymorphisms C677T and A1298C on Congenital Atrial Septal Defect Risk in an Iranian Cohort

Background

Congenital heart defects (CHD) are recognized as the most common heart abnormalities amongst newborns and children, and atrial septal defect (ASD) is recognized as one of the most frequent forms of CHD. Prior studies indicated that the methylenetetrahydrofolate reductase (MTHFR) gene contributes to the etiology of CHD. Therefore, we designed a case-control study to assess the possible role of the MTHFR gene, specifically the C677T (rs1801133) and A1298C (rs1801131) polymorphisms within the Iranian ASD population sample.

Methods

A total of 166 subjects (81 children diagnosed with ASD and 85 control participants) were enrolled in this research. Samples genotyped for MTHFR rs1801133 and rs1801131 polymorphisms using the PCR-RFLP and ARMS-PCR approaches.

Results

Our results indicated that rs1801131 variant reduced the risk of ASD in codominant (OR [95%CI]: 0.41[0.21-0.83], P=0.012), dominant (OR[95%CI]: 0.48 [0.25-0.93], p=0.028) and overdominant (OR[95%CI]: 0.44 [0.23-0.81], P=0.009) models. Moreover, rs1801133 variant increased the risk of ASD in codominant (OR[95%CI]: 2.68[1.39-5.16], P = 0.003), dominant (OR [95% CI]: 2.72 [1.43-5.14], P = 0.002), overdominant (OR [95% CI]: 2.50 [1.31-4.78], P = 0.005), and allelic (OR [95% CI]: 2.16 [1.27-3.69], P = 0.004) models.

Conclusions

Our findings suggest that MTHFR rs1801133 and rs1801131 variants may potentially affect the onset of ASD.

From genes to therapy: A comprehensive exploration of congenital heart disease through the lens of genetics and emerging technologies

Congenital heart disease (CHD) affects approximately 1 % of live births worldwide, making it the most common congenital anomaly in newborns. Recent advancements in genetics and genomics have significantly deepened our understanding of the genetics of CHDs. While the majority of CHD etiology remains unclear, evidence consistently indicates that genetics play a significant role in its development. CHD etiology holds promise for enhancing diagnosis and developing novel therapies to improve patient outcomes. In this review, we explore the contributions of both monogenic and polygenic factors of CHDs and highlight the transformative impact of emerging technologies on these fields. We also summarized the state-of-the-art techniques, including targeted next-generation sequencing (NGS), whole genome and whole exome sequencing (WGS, WES), single-cell RNA sequencing (scRNA-seq), human induced pluripotent stem cells (hiPSCs) and others, that have revolutionized our understanding of cardiovascular disease genetics both from diagnosis perspective and from disease mechanism perspective in children and young adults. These molecular diagnostic techniques have identified new genes and chromosomal regions involved in syndromic and non-syndromic CHD, enabling a more defined explanation of the underlying pathogenetic mechanisms. As our knowledge and technologies continue to evolve, they promise to enhance clinical outcomes and reduce the CHD burden worldwide.

Mitochondrial related variants associated with cardiovascular traits

Introduction

Cardiovascular disease (CVD) is responsible for over 30% of mortality worldwide. CVD arises from the complex influence of molecular, clinical, social, and environmental factors. Despite the growing number of autosomal genetic variants contributing to CVD, the cause of most CVDs is still unclear. Mitochondria are crucial in the pathophysiology, development and progression of CVDs; the impact of mitochondrial DNA (mtDNA) variants and mitochondrial haplogroups in the context of CVD has recently been highlighted.

Aims

We investigated the role of genetic variants in both mtDNA and nuclear-encoded mitochondrial genes (NEMG) in CVD, including coronary artery disease (CAD), hypertension, and serum lipids in the UK Biobank, with sub-group analysis for diabetes.

Methods

We investigated 371,542 variants in 2,527 NEMG, along with 192 variants in 32 mitochondrial genes in 381,994 participants of the UK Biobank, stratifying by presence of diabetes.

Results

Mitochondrial variants showed associations with CVD, hypertension, and serum lipids. Mitochondrial haplogroup J was associated with CAD and serum lipids, whereas mitochondrial haplogroups T and U were associated with CVD. Among NEMG, variants within Nitric Oxide Synthase 3 (NOS3) showed associations with CVD, CAD, hypertension, as well as diastolic and systolic blood pressure. We also identified Translocase Of Outer Mitochondrial Membrane 40 (TOMM40) variants associated with CAD; Solute carrier family 22 member 2 (SLC22A2) variants associated with CAD and CVD; and HLA-DQA1 variants associated with hypertension. Variants within these three genes were also associated with serum lipids.

Conclusion

Our study demonstrates the relevance of mitochondrial related variants in the context of CVD. We have linked mitochondrial haplogroup U to CVD, confirmed association of mitochondrial haplogroups J and T with CVD and proposed new markers of hypertension and serum lipids in the context of diabetes. We have also evidenced connections between the etiological pathways underlying CVDs, blood pressure and serum lipids, placing NOS3, SLC22A2, TOMM40 and HLA-DQA1 genes as common nexuses.

Embryonic Lethal Phenotyping to Identify Candidate Genes Related with Birth Defects

Congenital birth defects contribute significantly to preterm birth, stillbirth, perinatal death, infant mortality, and adult disability. As a first step to exploring the mechanisms underlying this major clinical challenge, we analyzed the embryonic phenotypes of lethal strains generated by random mutagenesis. In this study, we report the gross embryonic and perinatal phenotypes of 55 lethal strains randomly picked from a collection of mutants that carry piggyBac (PB) transposon inserts. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses suggested most of the analyzed mutations hit genes involved in heart and nervous development, or in Notch and Wnt signaling. Among them, 12 loci are known to be associated with human diseases. We confirmed 53 strains as embryonic or perinatal lethal, while others were subviable. Gross morphological phenotypes such as body size abnormality (29/55, 52.73%), growth or developmental delay (35/55, 63.64%), brain defects (9/55, 16.36%), vascular/heart development (31/55, 56.36%), and other structural defects (9/55, 16.36%) could be easily observed in the mutants, while three strains showed phenotypes similar to those of human patients. Furthermore, we detected body weight or body composition alterations in the heterozygotes of eight strains. One of them was the TGF-β signaling gene Smad2. The heterozygotes showed increased energy expenditure and a lower fat-to-body weight ratio compared to wild-type mice. This study provided new insights into mammalian embryonic development and will help understand the pathology of congenital birth defects in humans. In addition, it expanded our understanding of the etiology of obesity.

FLT4 gene polymorphisms influence isolated ventricular septal defect predisposition in a Southwest China population

BACKGROUND

Ventricular septal defect (VSD) is the most common congenital heart disease. Although a small number of genes associated with VSD have been found, the genetic factors of VSD remain unclear. In this study, we evaluated the association of 10 candidate single nucleotide polymorphisms (SNPs) with isolated VSD in a population from Southwest China.

METHODS

Based on the results of 34 congenital heart disease whole-exome sequencing and 1000 Genomes databases, 10 candidate SNPs were selected. A total of 618 samples were collected from the population of Southwest China, including 285 VSD samples and 333 normal samples. Ten SNPs in the case group and the control group were identified by SNaPshot genotyping. The chi-square (χ2) test was used to evaluate the relationship between VSD and each candidate SNP. The SNPs that had significant P value in the initial stage were further analysed using linkage disequilibrium, and haplotypes were assessed in 34 congenital heart disease whole-exome sequencing samples using Haploview software. The bins of SNPs that were in very strong linkage disequilibrium were further used to predict haplotypes by Arlequin software. ViennaRNA v2.5.1 predicted the haplotype mRNA secondary structure. We evaluated the correlation between mRNA secondary structure changes and ventricular septal defects.

RESULTS

The χ2 results showed that the allele frequency of FLT4 rs383985 (P = 0.040) was different between the control group and the case group (P < 0.05). FLT4 rs3736061 (r2 = 1), rs3736062 (r2 = 0.84), rs3736063 (r2 = 0.84) and FLT4 rs383985 were in high linkage disequilibrium (r2 > 0.8). Among them, rs3736061 and rs3736062 SNPs in the FLT4 gene led to synonymous variations of amino acids, but predicting the secondary structure of mRNA might change the secondary structure of mRNA and reduce the free energy.

CONCLUSIONS

These findings suggest a possible molecular pathogenesis associated with isolated VSD, which warrants investigation in future studies.

Genomic insights into heart health: Exploring the genetic basis of cardiovascular disease

Cardiovascular diseases (CVDs) are considered as the leading cause of death worldwide. CVD continues to be a major cause of death and morbidity despite significant improvements in its detection and treatment. Therefore, it is strategically important to be able to precisely characterize an individual's sensitivity to certain illnesses. The discovery of genes linked to cardiovascular illnesses has benefited from linkage analysis and genome-wide association research. The last 20 years have seen significant advancements in the field of molecular genetics, particularly with the development of new tools like genome-wide association studies. In this article we explore the profound impact of genetic variations on disease development, prognosis, and therapeutic responses. And the significance of genetics in cardiovascular risk assessment and the ever-evolving realm of genetic testing, offering insights into the potential for personalized medicine in this domain. Embracing the future of cardiovascular care, the article explores the implications of pharmacogenomics for tailored treatments, the promise of emerging technologies in cardiovascular genetics and therapies, including the transformative influence of nanotechnology. Furthermore, it delves into the exciting frontiers of gene editing, such as CRISPR/Cas9, as a novel approach to combat cardiovascular diseases. And also explore the potential of stem cell therapy and regenerative medicine, providing a holistic view of the dynamic landscape of cardiovascular genomics and its transformative potential for the field of cardiovascular medicine.

Biological Age in Congenital Heart Disease-Exploring the Ticking Clock

Over the past 50 years, there has been a major shift in age distribution of patients with congenital heart disease (CHD) thanks to significant advancements in medical and surgical treatment. Patients with CHD are, however, never cured and face unique challenges throughout their lives. In this review, we discuss the growing data suggesting accelerated aging in this population. Adults with CHD are more often and at a younger age confronted with age-related cardiovascular complications such as heart failure, arrhythmia, and coronary artery disease. These can be related to the original birth defect, complications of correction, or any residual defects. In addition, and less deductively, more systemic age-related complications are seen earlier, such as renal dysfunction, lung disease, dementia, stroke, and cancer. The occurrence of these complications at a younger age makes it imperative to further map out the aging process in patients across the spectrum of CHD. We review potential feasible markers to determine biological age and provide an overview of the current data. We provide evidence for an unmet need to further examine the aging paradigm as this stresses the higher need for care and follow-up in this unique, newly aging population. We end by exploring potential approaches to improve lifespan care.

The Impact of Integration of a Genetic Clinic Into a Pediatric Cardiac Unit

BACKGROUND

Previously published studies suggest that genetic or environmental causes can be observed in 20-30% of congenital heart disease (CHD) patients, which include aneuploidy, single gene defects, pathological copy number variations, and de novo autosomal dominant and recessive inheritance. Moreover, the genetic background of childhood cardiomyopathies (CMs) has not been elucidated well.

OBJECTIVE

The study highlights the value of genetic assessment in diagnosing and family counseling for CHD and pediatric CM patients referred to the genetic clinic in a pediatric cardiology department.

METHODS

The study involved patients less than 18 years of age attending the cardiogenetic clinic in the pediatric cardiology department between December 2010 and February 2019. The following patient categories who had genetic evaluation were included: CHD in the presence of a syndromic phenotype, patients with CHD having extracardiac congenital anomalies or delayed development, hypertrophic and dilated CM patients, patients with dilated aortic root and ascending aorta, significant CHD in siblings or first-degree relatives, suspected channelopathies; and interrupted aortic arch abnormalities.

RESULTS

A total of 285 patients were evaluated in the cardiogenetic clinic. The mean age was 20.2 months, with a range of 0-168. Females and males constituted 153 (53.7%) and 132 (46.3%), respectively. The most common cause of referral to the genetic clinic was the presence of CM (N=134 (46.3%)): hypertrophic CM in 24% and dilated CM in 20% of cases. Seventy-six patients (26.7%) had positive genetic results. The most common genetic abnormality was familial infantile hypertrophic CM-causing gene ELAC2 in 19 (23.5%) cases.

CONCLUSION

It may be beneficial for any pediatric cardiology unit to provide an established genetic clinic. Using a genetic clinic will enhance understanding of CHD pathophysiology, family education, and genetic counseling. Agreement on a well-written protocol and the way forward to specify what congenital heart conditions require genetic investigation should be clarified.

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.

WDR62 variants contribute to congenital heart disease by inhibiting cardiomyocyte proliferation

Background

Congenital heart disease (CHD) is the most common birth defect and has high heritability. Although some susceptibility genes have been identified, the genetic basis underlying the majority of CHD cases is still undefined.

Methods

A total of 1320 unrelated CHD patients were enrolled in our study. Exome‐wide association analysis between 37 tetralogy of Fallot (TOF) patients and 208 Han Chinese controls from the 1000 Genomes Project was performed to identify the novel candidate gene WD repeat‐containing protein 62 (WDR62). WDR62 variants were searched in another expanded set of 200 TOF patients by Sanger sequencing. Rescue experiments in zebrafish were conducted to observe the effects of WDR62 variants. The roles of WDR62 in heart development were examined in mouse models with Wdr62 deficiency. WDR62 variants were investigated in an additional 1083 CHD patients with similar heart phenotypes to knockout mice by multiplex PCR‐targeting sequencing. The cellular phenotypes of WDR62 deficiency and variants were tested in cardiomyocytes, and the molecular mechanisms were preliminarily explored by RNA‐seq and co‐immunoprecipitation.

Results

Seven WDR62 coding variants were identified in the 237 TOF patients and all were indicated to be loss of function variants. A total of 25 coding and 22 non‐coding WDR62 variants were identified in 80 (6%) of the 1320 CHD cases sequenced, with a higher proportion of WDR62 variation (8%) found in the ventricular septal defect (VSD) cohort. WDR62 deficiency resulted in a series of heart defects affecting the outflow tract and right ventricle in mouse models, including VSD as the major abnormality. Cell cycle arrest and an increased number of cells with multipolar spindles that inhibited proliferation were observed in cardiomyocytes with variants or knockdown of WDR62. WDR62 deficiency weakened the association between WDR62 and the cell cycle‐regulated kinase AURKA on spindle poles, reduced the phosphorylation of AURKA, and decreased expression of target genes related to cell cycle and spindle assembly shared by WDR62 and AURKA.

Conclusions

WDR62 was identified as a novel susceptibility gene for CHD with high variant frequency. WDR62 was shown to participate in the cardiac development by affecting spindle assembly and cell cycle pathway in cardiomyocytes.

Epigenetics and Congenital Heart Diseases

Congenital heart disease (CHD) is a frequent occurrence, with a prevalence rate of almost 1% in the general population. However, the pathophysiology of the anomalous heart development is still unclear in most patients screened. A definitive genetic origin, be it single-point mutation or larger chromosomal disruptions, only explains about 35% of identified cases. The precisely choreographed embryology of the heart relies on timed activation of developmental molecular cascades, spatially and temporally regulated through epigenetic regulation: chromatin conformation, DNA priming through methylation patterns, and spatial accessibility to transcription factors. This multi-level regulatory network is eminently susceptible to outside disruption, resulting in faulty cardiac development. Similarly, the heart is unique in its dynamic development: growth is intrinsically related to mechanical stimulation, and disruption of the intrauterine environment will have a direct impact on fetal embryology. These two converging axes offer new areas of research to characterize the cardiac epigenetic regulation and identify points of fragility in order to counteract its teratogenic consequences.

Tissue engineering: Relevance to neonatal congenital heart disease

Congenital heart disease (CHD) represents a large clinical burden, representing the most common cause of birth defect-related death in the newborn. The mainstay of treatment for CHD remains palliative surgery using prosthetic vascular grafts and valves. These devices have limited effectiveness in pediatric patients due to thrombosis, infection, limited endothelialization, and a lack of growth potential. Tissue engineering has shown promise in providing new solutions for pediatric CHD patients through the development of tissue engineered vascular grafts, heart patches, and heart valves. In this review, we examine the current surgical treatments for congenital heart disease and the research being conducted to create tissue engineered products for these patients. While much research remains to be done before tissue engineering becomes a mainstay of clinical treatment for CHD patients, developments have been progressing rapidly towards translation of tissue engineering devices to the clinic.

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.

The role of NKX2-5 gene polymorphisms in congenital heart disease (CHD): a systematic review and meta-analysis

BACKGROUND

The gene NKX2-5 is a key transcription factor that plays an essential role in normal cardiac development. Although some recent studies have studied the role of polymorphisms in the NKX2-5 gene in congenital heart diseases (CHDs), the results were not consistent and remained uncertain. Therefore, we conduct a review of literature and investigate the association of genetic polymorphisms with CHDs.

RESULTS

We selected seventeen studies regarding the association of NKX2-5 gene rs2277923 polymorphism with CHDs. Overall, in all the tested genetic models, the 63A > G polymorphism was not significantly associated with increased congenital heart defects risk. We used pooled odds ratios (OR) to calculate the association of CHDs with rs2277923 including allelic model: OR 1.00, 95% CI 0.82-1.21; homozygote model: OR 0.95, 95%CI 0.68-1.33, recessive model: OR 0.89 CI 0.70-1.13, heterozygote model: OR: 1.09, 95%CI 0.87-1.37, dominant model: OR 1.08 CI 0.82-1.42 and overdominant model: OR 1.17 CI 1.01-1.35. In addition, our analysis suggests that no publication bias exists in this meta-analysis.

CONCLUSIONS

Our findings suggested that 63A > G polymorphism in the NKX2-5 gene was not significantly associated with congenital heart defects. However, in the future, more studies with increased sample size are required that may provide us more definite conclusions.

Association analysis of maternal MTHFR gene polymorphisms and the occurrence of congenital heart disease in offspring

BACKGROUND

Although many studies showed that the risk of congenital heart disease (CHD) was closely related to genetic factors, the exact pathogenesis is still unknown. Our study aimed to comprehensively assess the association of single nucleotide polymorphisms (SNPs) of maternal MTHFR gene with risk of CHD and its three subtypes in offspring.

METHODS

A case-control study involving 569 mothers of CHD cases and 652 health controls was conducted. Thirteen SNPs were detected and analyzed.

RESULTS

Our study showed that genetic polymorphisms of maternal MTHFR gene at rs4846052 and rs1801131 were significantly associated with risk of CHD in the homozygote comparisons (TT vs. CC at rs4846052: OR = 7.62 [95%CI 2.95-19.65]; GG vs. TT at rs1801131: OR = 5.18 [95%CI 2.77-9.71]). And six haplotypes of G-C (involving rs4846048 and rs2274976), A-C (involving rs1801133 and rs4846052), G-T (involving rs1801133 and rs4846052), G-T-G (involving rs2066470, rs3737964 and rs535107), A-C-G (involving rs2066470, rs3737964 and rs535107) and G-C-G (involving rs2066470, rs3737964 and rs535107) were identified to be significantly associated with risk of CHD. Additionally, we observed that a two-locus model involving rs2066470 and rs1801131 as well as a three-locus model involving rs227497, rs1801133 and rs1801131 were significantly associated with risk of CHD in the gene-gene interaction analyses. For three subtypes including atrial septal defect, ventricular septal defect and patent ductus arteriosus, similar results were observed.

CONCLUSIONS

Our study indicated genetic polymorphisms of maternal MTHFR gene were significantly associated with risk of fetal CHD in the Chinese population. Additionally, there were significantly interactions among different SNPs on risk of CHD. However, how these SNPs affect the development of fetal heart remains unknown, and more studies in different ethnic populations and with a larger sample are required to confirm these findings.

Integrated microRNA and mRNA Expression Profiling Identifies Novel Targets and Networks Associated with Ebstein's Anomaly

Little is known about abundance level changes of circulating microRNAs (miRNAs) and messenger RNAs (mRNA) in patients with Ebstein’s anomaly (EA). Here, we performed an integrated analysis to identify the differentially abundant miRNAs and mRNA targets and to identify the potential therapeutic targets that might be involved in the mechanisms underlying EA. A large panel of human miRNA and mRNA microarrays were conducted to determine the genome-wide expression profiles in the blood of 16 EA patients and 16 age and gender-matched healthy control volunteers (HVs). Differential abundance level of single miRNA and mRNA was validated by Real-Time quantitative PCR (RT-qPCR). Enrichment analyses of altered miRNA and mRNA abundance levels were identified using bioinformatics tools. Altered miRNA and mRNA abundance levels were observed between EA patients and HVs. Among the deregulated miRNAs and mRNAs, 76 miRNAs (49 lower abundance and 27 higher abundance, fold-change of ≥2) and 29 mRNAs (25 higher abundance and 4 lower abundance, fold-change of ≥1.5) were identified in EA patients compared to HVs. Bioinformatics analysis identified 37 pairs of putative miRNA-mRNA interactions. The majority of the correlations were detected between the lower abundance level of miRNA and higher abundance level of mRNA, except for let-7b-5p, which showed a higher abundance level and their target gene, SCRN3, showed a lower abundance level. Pathway enrichment analysis of the deregulated mRNAs identified 35 significant pathways that are mostly involved in signal transduction and cellular interaction pathways. Our findings provide new insights into a potential molecular biomarker(s) for the EA that may guide the development of novel targeting therapies.

Rapid whole genome sequencing impacts care and resource utilization in infants with congenital heart disease

Congenital heart disease (CHD) is the most common congenital anomaly and a major cause of infant morbidity and mortality. While morbidity and mortality are highest in infants with underlying genetic conditions, molecular diagnoses are ascertained in only ~20% of cases using widely adopted genetic tests. Furthermore, cost of care for children and adults with CHD has increased dramatically. Rapid whole genome sequencing (rWGS) of newborns in intensive care units with suspected genetic diseases has been associated with increased rate of diagnosis and a net reduction in cost of care. In this study, we explored whether the clinical utility of rWGS extends to critically ill infants with structural CHD through a retrospective review of rWGS study data obtained from inpatient infants < 1 year with structural CHD at a regional children's hospital. rWGS diagnosed genetic disease in 46% of the enrolled infants. Moreover, genetic disease was identified five times more frequently with rWGS than microarray ± gene panel testing in 21 of these infants (rWGS diagnosed 43% versus 10% with microarray ± gene panels, p = 0.02). Molecular diagnoses ranged from syndromes affecting multiple organ systems to disorders limited to the cardiovascular system. The average daily hospital spending was lower in the time period post blood collection for rWGS compared to prior (p = 0.003) and further decreased after rWGS results (p = 0.000). The cost was not prohibitive to rWGS implementation in the care of this cohort of infants. rWGS provided timely actionable information that impacted care and there was evidence of decreased hospital spending around rWGS implementation.

Gestational intermittent hyperoxia rescues murine genetic congenital heart disease in part

Cardiac development is a dynamic process, temporally and spatially. When disturbed, it leads to congenital cardiac anomalies that affect approximately 1% of live births. Genetic variants in several loci lead to anomalies, with the transcription factor NKX2-5 being one of the largest. However, there are also non-genetic factors that influence cardiac malformations. We examined the hypothesis that hyperoxia may be beneficial and can rescue genetic cardiac anomalies induced by an Nkx2-5 mutation. Intermittent mild hyperoxia (40% PO₂) was applied for 10 h per day to normal wild-type female mice mated with heterozygous Nkx2-5 mutant males from gestational day 8.5 to birth. Hyperoxia therapy reduced excessive trabeculation in Nkx2-5 mutant mice compared to normoxic conditions (ratio of trabecular layer relative to compact layer area, normoxia 1.84 ± 0.07 vs. hyperoxia 1.51 ± 0.04) and frequency of muscular ventricular septal defects per heart (1.53 ± 0.32 vs. 0.68 ± 0.15); however, the incidence of membranous ventricular septal defects in Nkx2-5 mutant hearts was not changed. Nkx2-5 mutant embryonic hearts showed defective coronary vessel organization, which was improved by intermittent mild hyperoxia. The results of our study showed that mild gestational hyperoxia therapy rescued genetic cardiac malformation induced by Nkx2-5 mutation in part.

First report of polymorphisms in MTRR, GATA4, VEGF, and ISL1 genes in Pakistani children with isolated ventricular septal defects (VSD)

BACKGROUND

Ventricular septal defects (VSDs) are malformations in the septum separating the heart's ventricles. VSDs may present as a single anomaly (isolated/nonsyndromic VSD) or as part of a group of phenotypes (syndromic VSD). The exact location of the defect is crucial in linking the defect to the underlying genetic cause. The number of children visiting cardiac surgery units is constantly increasing. However, there are no representative data available on the genetics of VSDs in Pakistani children.

METHODS

Two hundred forty-two subjects (121 VSD children and 121 healthy controls) were recruited from pediatric cardiac units of Lahore. The clinical and demographic data of the subjects were collected. A total of four SNPs, one each from MTRR, GATA4, VEGF, and ISL1 genes were genotyped by PCR-RFLP.

RESULTS

The results showed that the minor allele (T) frequency (MAFs) for the MTRR gene variant rs1532268 (c.524C > T) was 0.20 and 0.41 in the controls and the cases, respectively, with the genotype frequencies 3, 35, 62% in the controls and 12, 59 and 29% in the cases for TT, CT, CC genotypes, respectively (allelic OR: 5.73, CI: 3.82-8.61, p-value: 5.11 × 10^- 7). For the GATA4 variant rs104894073 (c.886G > A), the MAF for the controls and the cases was 0.16 and 0.37, respectively, the frequencies of AA, GA and GG genotypes were 2, 28, and 70% in the controls and 5, 64 and 31% of the cases (allelic OR: 3.08, CI: 2.00-4.74, p-value: 8.36 × 10^- 8). The rs699947 (c.-2578C > A) of VEGF gene showed MAF 0.36 and 0.53 for the controls and cases, respectively, with the genotype frequencies 13, 42, and 45% in the controls and 22, 15, and 63% in the cases for the AA, CA, CC (allelic OR: 2.03, CI: 1.41-2.92, p-value: 0.0001). The ISL1 gene variant rs6867206 (g.51356860 T > C), the MAFs were 0.26 and 0.31 in the controls and cases, respectively. The genotype frequencies were 48, 52, 0% in the controls and 39, 61, 0% in the cases for TT, TC, CC genotypes (allelic OR: 0.27, CI: 0.85-1.89, p-value: 0.227). The MTRR, GATA4 and VEGF variants showed association while ISL1 variant did not appear to be associated with the VSD in the recruited cohort.

CONCLUSION

This first report in Pakistani children demonstrates that single nucleotide polymorphisms in genes encoding transcription factors, signaling molecules and structural heart genes involved in fetal heart development are associated with developmental heart defects., however further work is needed to validate the results of the current investigation.

Analysis of Copy Number Variations by Low-Depth Whole-Genome Sequencing in Fetuses with Congenital Cardiovascular Malformations

Congenital cardiovascular malformations (CVMs) due to genomic mutations bring a greater risk of morbidity and comorbidity and increase the risks related to heart surgery. However, reports on CVMs induced by genomic mutations based on actual clinical data are still limited. In this study, 181 fetuses were screened by fetal echocardiography for prenatal diagnosis of congenital heart disease, including 146 cases without ultrasound extracardiac findings (Group A) and 35 cases with ultrasound extracardiac findings (Group B). All cases were analyzed by clinical data, karyotyping, and low-depth whole-genome sequencing. The rates of chromosomal abnormalities in Groups A and B were 4.8% (7/146) and 37.1% (13/35), respectively. There was a significant difference in the incidence of chromosomal abnormalities between Groups A and B (p < 0.001). In Group A, CNV-seq identified copy number variations (CNVs) in an additional 9.6% (14/146) of cases with normal karyotypes, including 7 pathogenic CNVs and 7 variations of uncertain clinical significance. In Group B, one pathogenic CNV was identified in a case with normal karyotype. Chromosomal abnormality is one of the most common causes of CVM with extracardiac defects. Low-depth whole-genome sequencing could effectively become a first approach for CNV diagnosis in fetuses with CVMs.

Associations between weekly air pollution exposure and congenital heart disease

BACKGROUND

The topic of congenital heart diseases (CHDs) has attracted more and more attentions. Accumulating evidence suggests that exposure to air pollutants during pregnancy is associated with CHDs, yet the results are inconsistent and study about weekly exposure is few. Our study evaluated the association between weekly air pollution and CHDs in Hefei, China.

MATERIALS AND METHODS

Daily CHDs admission data were obtained from eight hospitals in Hefei from October 2015 to September 2017. Meteorological data and air quality were collected from China Meteorological Data Network. Distributed lag nonlinear model (DLNM) considering both the lag effect of exposure factors and the nonlinear relationship of exposure-reaction was used to assess the effect of weekly air pollutants exposure on CHDs admission.

RESULTS

During the study period, totally 47,046 cases of perinatal infants were recruited, and the incidence of CHDs was 9.71 per thousand. The findings showed PM_2.5, PM₁₀, SO₂ and NO₂ significantly increased the risk of CHDs. Each 10 μg/m³ increase in PM_2.5 during gestational weeks 20-26 increased the risk of CHDs. The susceptibility windows of PM₁₀ (weeks 0-2 and weeks 25-29 of pregnancy), SO₂ (weeks 8-16 and weeks 29-38) and NO₂ (week 40), while the strongest effects of these 4 pollutants on CHDs were observed in week 22 (RR = 1.034, 95% CI: 1.007-1.062), week 0 (RR = 1.081, 95% CI: 1.02-1.146), week 37 (RR = 1.528, 95% CI: 1.085-2.153) and week 40 (RR = 1.171, 95% CI: 1.006-1.364), respectively.

CONCLUSIONS

Air pollutants (SO₂, NO₂, PM₁₀, and PM_2.5) exposure could increase the risk of CHDs, while the most crucial susceptibility windows for the exposure were mainly in the second and third trimesters. Boys seemed to be more sensitive to air pollution. Our study contributes to the knowledge of the association between maternal exposure to air pollution and CHDs, but the associations need to be verified by further studies.

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.

Unraveling the genomic basis of congenital heart disease

The genetic, epigenetic, and environmental etiologic basis of congenital heart disease (CHD) for most heart anomalies remains unexplained. In this issue of the JCI, Lahm et al. performed the largest genome-wide association study (GWAS) to date of European individuals with CHD and clinical subtypes. The comprehensive meta-analysis included over 4000 patients and 8000 controls and uncovered common genetic variants that associated with cardiac anomalies. Lahm and colleagues performed single-cell analysis of induced pluripotent stem cells and heart cells, revealing a role for MACROD2, GOSR2, WNT3, and MSX1 in the developing heart. This study advances our understanding of the genetic basis of common forms of CHD.

Challenges in the Surgical Treatment of Atrioventricular Septal Defect in Children With and Without Down Syndrome in Romania-A Developing Country

Background: Atrioventricular septal defect (AVSD) is a cardiac malformation that accounts for up to 5% of total congenital heart disease, occurring with high frequency in people with Down Syndrome (DS). We aimed to establish the surgical challenges and outcome of medical care in different types of AVSD in children with DS compared to those without DS (WDS). Methods: The study included 62 children (31 with DS) with AVSD, evaluated over a 5 year period. Results: Complete AVSD was observed in 49 (79%) children (27 with DS). Six children had partial AVSD (all WDS) and seven had intermediate types of AVSD (4 with DS). Eight children had unbalanced complete AVSD (1 DS). Median age at diagnosis and age at surgical intervention in complete AVSD was not significantly different in children with DS compared to those WDS (7.5 months vs. 8.6). Median age at surgical intervention for partial and transitional AVSDs was 10.5 months for DS and 17.8 months in those without DS. A large number of patients were not operated: 13/31 with DS and 8/31 WDS. Conclusion: The complete form of AVSD was more frequent in DS group, having worse prognosis, while unbalanced AVSD was observed predominantly in the group without DS. Children with DS required special attention due to increased risk of pulmonary hypertension. Late diagnosis was an important risk factor for poor prognosis, in the setting of suboptimal access to cardiac surgery for patients in Romania. Although post-surgery mortality was low, infant mortality before surgery remains high. Increased awareness is needed in order to provide early diagnosis of AVSD and enable optimal surgical treatment.

Epidemiological Research of Microtia Combined With Congenital Heart Disease

Congenital heart disease (CHD) is one of the most common combined malformations of microtia. There is currently no specific study that investigates the relationship between microtia and CHD.

METHODS

This study collected microtia inpatients admitted from May 1, 2015 to July 31, 2016. The diagnosis of CHD was based on patient's symptoms, past history, and echocardiography. Pearson χ test was used to analyze the correlation between CHD and microtia.

RESULTS

A total of 30 cases (3.35%) were documented with CHD, including atrial septal defect (12/40.00%), ventricular septal defect (7/23.30%), patent ductus arteriosus (2/6.70%), complex congenital heart disease (3/10.00%), combined CHD (2/6.70%) and other malformations (4/13.30%). Analysis showed no statistically significant relation between CHD and the side of affected ear or gender.

CONCLUSIONS

The occurrence of CHD in microtia patients was higher than that in the general population. The relationship between them was explored mainly from the etiological perspective. Microtia and CHD were often combined in syndromes such as Goldenhar syndrome, 22q11 deletion syndrome, and CHARGE syndrome. Absence of genes or abnormal embryo development associated with these syndromes leads to the occurrence of both.

An update on genetic variants of the NKX2-5

NKX2-5 is a homeodomain transcription factor that plays a crucial role in heart development. It is the first gene where a single genetic variant (GV) was found to be associated with congenital heart diseases in humans. In this study, we carried out a comprehensive survey of NKX2-5 GVs to build a unified, curated, and updated compilation of all available GVs. We retrieved a total of 1,380 unique GVs. From these, 970 had information on their frequency in the general population and 143 have been linked to pathogenic phenotypes in humans. In vitro effect was ascertained for 38 GVs. The homeodomain had the biggest cluster of pathogenic variants in the protein: 49 GVs in 60 residues, 23 in its third α-helix, where 11 missense variants may affect protein-DNA interaction or the hydrophobic core. We also pinpointed the likely location of pathogenic GVs in four linear motifs. These analyses allowed us to assign a putative explanation for the effect of 90 GVs. This study pointed to reliable pathogenicity for GVs in helix 3 of the homeodomain and may broaden the scope of functional and structural studies that can be done to better understand the effect of GVs in NKX2-5 function.

The rate of undetectable genetic causes by Cell-free DNA test in congenital heart defects

Objective: The study aimed to estimate the rate of genetic causes that were undetectable by Cell-free DNA (cfDNA) test in prenatally diagnosed congenital heart defect (CHD) cases based on an assumption that cfDNA would accurately detect common aneuploidies including trisomy 21/18/13/45X, and del22q11.2.Methods: This study included prenatally diagnosed CHD cases with diagnostic genetic results. The possibility of false-positive/negative results from cfDNA testing was discarded. Thus, cfDNA results would be positive in common aneuploidies or del22q11.2 and negative in normal diagnostic genetic testing results or other genetic conditions. The rate of genetic causes that were undetectable by cfDNA test was estimated for all cases as well as for CHD subgroups.Results: Of 302 cases, 98 (34.8%) had a type of genetic abnormalities, with 67 having common aneuploidies or del22q11.2 and 31 having other genetic conditions. The rate of genetic causes that were undetectable by cfDNA test in CHD cases was 13.2% among those with assumingly negative cfDNA screen results and 10.3% among the entire study population. These rates were similar between CHD subgroups (p > .05). The rate of genetic causes that were undetectable by cfDNA test was higher in the non-isolated cases than in the isolated ones among those with assumingly negative-screen results (20.5% and 9.9%, respectively, p = .025).Conclusion: In prenatally diagnosed CDH cases, a significant number of chromosomal abnormalities are still identified after diagnostic testing even if cfDNA screen is negative, and thus it is important to extensively counsel patients with negative cfDNA screen carrying a CHD-affected fetus.

CACCT: An Automated Tool of Detecting Complicated Cardiac Malformations in Mouse Models

Congenital heart disease (CHD) is the major cause of morbidity/mortality in infancy and childhood. Using a mouse model to uncover the mechanism of CHD is essential to understand its pathogenesis. However, conventional 2D phenotyping methods cannot comprehensively exhibit and accurately distinguish various 3D cardiac malformations for the complicated structure of heart cavity. Here, a new automated tool based on microcomputed tomography (micro-CT) image data sets known as computer-assisted cardiac cavity tracking (CACCT) is presented, which can detect the connections between cardiac cavities and identify complicated cardiac malformations in mouse hearts automatically. With CACCT, researchers, even those without expert training or diagnostic experience of CHD, can identify complicated cardiac malformations in mice conveniently and precisely, including transposition of the great arteries, double-outlet right ventricle and atypical ventricular septal defect, whose accuracy is equivalent to senior fetal cardiologists. CACCT provides an effective approach to accurately identify heterogeneous cardiac malformations, which will facilitate the mechanistic studies into CHD and heart development.

Dysregulated micro-RNAs and long noncoding RNAs in cardiac development and pediatric heart failure

Noncoding RNAs (ncRNAs) are broadly described as RNA molecules that are not translated into protein. The investigation of dysregulated ncRNAs in human diseases such as cancer, neurological, and cardiovascular diseases has been under way for well over a decade. Micro-RNAs and long noncoding RNAs (lncRNAs) are the best characterized ncRNAs. These ncRNAs can have profound effects on the regulation of gene expression during cardiac development and disease. Importantly, ncRNAs are significant regulators of gene expression in several congenital heart diseases and can positively or negatively impact cardiovascular development. In this review, we focus on literature involving micro-RNAs and lncRNAs in the context of pediatric cardiovascular diseases, preclinical models of heart failure, and cardiac development.

A novel de novo dominant mutation of NOTCH1 gene in an Iranian family with non-syndromic congenital heart disease

Background

Congenital heart disease (CHD) is the most common birth defect which can arises from different genetic defects. The genetic heterogeneity of this disease leads to restricted success in candidate genes screening method. Emerging approaches such as next‐generation sequencing (NGS)‐based genetic analysis might provide a better understating of CHD etiology in the patients who are left undiagnosed. To this aim, in this study, we survived the causes of CHD in an Iranian family who was consanguineous and had two affected children.

Methods

Affected individuals of this family were checked previously by PCR‐direct sequencing for six candidate genes (NKX2‐5, ZIC3, NODAL, FOXH1, GJA1, GATA4) and had not revealed any reported CHD causative mutations. Whole‐exome sequencing (WES) was performed on this family probond to determine the underlying cause of CHD, and the identified variants were confirmed and segregated by Sanger sequencing.

Results

We identified one heterozygous missense mutation, c.T6797C (p.Phe2266Ser), in the NOTCH1 gene, which seems to be the most probably disease causing of this family patients. This mutation was found to be novel and not reported on 1000 Genomes Project, dbSNP, and ExAC.

Conclusion

Worldwide, mutations in NOTCH1 gene are considered as one of the most known causes of CHD. The found NOTCH1 variant in this family affected individuals was the first report from Iran. Yet again, this result indicates the importance of NOTCH1 screening in CHD patients.

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.

Gene-environment regulatory circuits of right ventricular pathology in tetralogy of fallot

The phenotypic spectrum of congenital heart defects (CHDs) is contributed by both genetic and environmental factors. Their interactions are profoundly heterogeneous but may operate on common pathways as in the case of hypoxia signaling during postnatal heart development in the context of CHDs. Tetralogy of Fallot (TOF) is the most common cyanotic (hypoxemic) CHD. However, how the hypoxic environment contributes to TOF pathogenesis after birth is poorly understood. We performed Genome-wide transcriptome analysis on right ventricle outflow tract (RVOT) specimens from cyanotic and noncyanotic TOF. Co-expression network analysis identified gene modules specifically associated with clinical diagnosis and hypoxemia status in the TOF hearts. In particular, hypoxia-dependent induction of myocyte proliferation is associated with E2F1-mediated cell cycle regulation and repression of the WNT11-RB1 axis. Genes enriched in epithelial mesenchymal transition (EMT), fibrosis, and sarcomere were also repressed in cyanotic TOF patients. Importantly, transcription factor analysis of the hypoxia-regulated modules suggested CREB1 as a putative regulator of hypoxia/WNT11-RB1 circuit. The study provides a high-resolution landscape of transcriptome programming associated with TOF phenotypes and unveiled hypoxia-induced regulatory circuit in cyanotic TOF. Hypoxia-induced cardiomyocyte proliferation involves negative modulation of CREB1 activity upstream of the WNT11-RB1 axis. KEY MESSAGES: Genetic and environmental factors contribute to congenital heart defects (CHDs). How hypoxia contributes to Tetralogy of Fallot (TOF) pathogenesis after birth is unclear. Systems biology-based analysis revealed distinct molecular signature in CHDs. Gene expression modules specifically associated with cyanotic TOF were uncovered. Key regulatory circuits induced by hypoxia in TOF pathogenesis after birth were unveiled.

Risk of congenital heart defects in offspring exposed to maternal diabetes mellitus: an updated systematic review and meta-analysis

PURPOSE

A systematic review and meta-analysis was performed to assess the risk of congenital heart defects (CHDs) and its specific phenotypes associated with maternal diabetes mellitus (DM) including pregestational diabetes mellitus (PGDM) and gestational diabetes mellitus (GDM).

METHODS

PubMed, Embase, Medline, Google Scholar, Cochrane Libraries, China National Knowledge Infrastructure, Wanfang Database, Chinese Scientific Journals Fulltext Database and China Biology Medicine disc were searched from the inception dates to 15 December 2018, to identify case-control or cohort studies assessing the association between maternal DM and risk of CHDs. The exposure of interest was maternal DM; the outcomes of interest were CHDs and its specific phenotypes. Either a fixed- or a random-effects model was used to calculate the overall combined risk estimates. Subgroup analyses were performed to explore potential heterogeneity moderators.

RESULTS

Total 52 studies, which involved 259,917 patients with CHDs among 16,929,835 participants, were included for analysis. Overall, mothers with DM compared with those without DM had a significantly higher risk of CHDs in offspring [odds ratios (OR) = 2.71, 95% confidence intervals (CI) 2.28-3.23]. When data were restricted to different types of DM, a significantly increased risk of CHDs was observed among mothers with PGDM (OR = 3.18, 95% CI 2.77-3.65) and GDM (OR = 1.98, 95% CI 1.66-2.36). Our study suggested the risk of CHDs was significantly higher among mothers with PGDM than those with GDM. Additionally, this study suggested maternal DM was significantly associated with most phenotypes of CHDs; of these, double outlet of the right ventricle (OR = 10.89; 95% CI 8.77-13.53), atrioventricular septal defect (OR = 5.74; 95% CI 3.20-10.27) and truncus arteriosus (OR = 5.06; 95% CI 2.65-9.65) were identified as the first three of the most common phenotypes of CHDs associated with maternal DM.

CONCLUSIONS

The maternal DM including PGDM and GDM are significantly associated with risk of CHDs and its most phenotypes. The PGDM seems to be more likely to cause CHDs in offspring than GDM. Further studies are needed to clarify the underlying mechanisms.

The Role of Non-Coding RNA in Congenital Heart Diseases

Cardiovascular development is a complex developmental process starting with the formation of an early straight heart tube, followed by a rightward looping and the configuration of atrial and ventricular chambers. The subsequent step allows the separation of these cardiac chambers leading to the formation of a four-chambered organ. Impairment in any of these developmental processes invariably leads to cardiac defects. Importantly, our understanding of the developmental defects causing cardiac congenital heart diseases has largely increased over the last decades. The advent of the molecular era allowed to bridge morphogenetic with genetic defects and therefore our current understanding of the transcriptional regulation of cardiac morphogenesis has enormously increased. Moreover, the impact of environmental agents to genetic cascades has been demonstrated as well as of novel genomic mechanisms modulating gene regulation such as post-transcriptional regulatory mechanisms. Among post-transcriptional regulatory mechanisms, non-coding RNAs, including therein microRNAs and lncRNAs, are emerging to play pivotal roles. In this review, we summarize current knowledge on the functional role of non-coding RNAs in distinct congenital heart diseases, with particular emphasis on microRNAs and long non-coding RNAs.

A familial congenital heart disease with a possible multigenic origin involving a mutation in BMPR1A

The genetics of many congenital heart diseases (CHDs) can only unsatisfactorily be explained by known chromosomal or Mendelian syndromes. Here, we present sequencing data of a family with a potentially multigenic origin of CHD. Twelve of nineteen family members carry a familial mutation [NM_004329.2:c.1328 G > A (p.R443H)] which encodes a predicted deleterious variant of BMPR1A. This mutation co-segregates with a linkage region on chromosome 1 that associates with the emergence of severe CHDs including Ebstein's anomaly, atrioventricular septal defect, and others. We show that the continuous overexpression of the zebrafish homologous mutation bmpr1aa^p.R438H within endocardium causes a reduced AV valve area, a downregulation of Wnt/ß-catenin signalling at the AV canal, and growth of additional tissue mass in adult zebrafish hearts. This finding opens the possibility of testing genetic interactions between BMPR1A and other candidate genes within linkage region 1 which may provide a first step towards unravelling more complex genetic patterns in cardiovascular disease aetiology.

Dioxin and AHR impairs mesoderm gene expression and cardiac differentiation in human embryonic stem cells

Dioxin and dioxin-related polychlorinated biphenyls are potent toxicants with association with developmental heart defects and congenital heart diseases. However, the underlying mechanism of their developmental toxicity is not fully understood. Further, different animals show distinct susceptibility and phenotypes after exposure, suggesting possible species-specific effects. Using a human embryonic stem cell (ESC) cardiomyocyte differentiation model, we examined the impact, susceptible window, and dosage of 2,3,7,8‑tetrachlorodibenzo‑p‑dioxin (TCDD) on human cardiac development. We showed that treatment of human ESCs with TCDD at the ESC stage inhibits cardiomyocyte differentiation, and the effect is largely mediated by the aryl hydrocarbon receptor (AHR). We further identified genes that are differentially expressed after TCDD treatment by RNA-sequencing, and genomic regions that are occupied by AHR by chromatin immunoprecipitation and high-throughput sequencing. Our results support the model that TCDD impairs human ESC cardiac differentiation by promoting AHR binding and repression of key mesoderm genes. More importantly, our study demonstrates the toxicity of dioxin in human embryonic development and uncovered a novel mechanism by which dioxin and AHR regulates lineage commitment. It also illustrates the power of ESC-based models in the systematic study of developmental toxicology.

Implication of GATA4 synonymous variants in congenital heart disease: A comprehensive in-silico approach

Synonymous variations, previously considered as neutral, are recently shown to have a significant impact on mRNA structure and stability thereby affecting protein expression and function. Their role in disease pathogenesis is also emerging. GATA4 is an important transcription factor involved in cardiac development and a well-known candidate gene associated with congenital heart disease (CHD). In the present study, we sought to conduct molecular screening of GATA4 gene in 285 sporadic and non-syndromic CHD cases. We identified four synonymous (c.27C>A, c.822C>T, c.1233G>A and c.1263C>T) and two intronic variants (g.83217T>G & g.85012T>A) in GATA4. Extensive computational analysis using widely acceptable tools i.e., Mfold, Human Splicing Finder (HSF) and Codon Usage bias was performed with a view to understand their putative downstream effects on GATA4 function. Mfold, a mRNA structure prediction tool showed the alterations of the mRNA structure and stability due to synonymous variants. Similarly, HSF also confidently predicted effect on the cis-acting regulatory elements of splicing due to four synonymous and one donor site intronic variants. Additionally, a significant change in 'Relative Synonymous Codon usage (RSCU) frequencies' and 'log ratio of codon usage frequencies' of variant codon was also noted that might affect the rate of translation. This study establishes that the synonymous variants are possibly associated with disease phenotype in CHD patients. Comprehensive computational analysis, using well-established web based tools, is suggestive of their potential downstream molecular effects on the structure, stability and expression of GATA4 protein.

Association between the promoter methylation of the TBX20 gene and tetralogy of fallot

OBJECTIVES

To investigate the association between promoter methylation of the TBX20 gene and tetralogy of Fallot (TOF)． Methods. The methylation level of TBX20 promoter regions in 23 patients with TOF and five controls were analyzed through bisulfite sequencing polymerase chain reaction. Meanwhile, the expression of TBX20 mRNA was measured using real time fluorescence quantitative polymerase chain reaction.

RESULTS

The region -400 to -48 in the TBX20 promoter consisting of 42 CpG sites was predicted to contain multiple transcription factor binding sites. In this study, the overall methylation level in this region was lower in patients with TOF than in the controls (P = .035). Among the 42 CpG sites, the methylation percentages of the CpG 26 site in the TOF cases were lower than those in the controls (P = .016). The mRNA expression of TBX20 in the right ventricular outflow tract myocardium was increased in TOF cases in contrast to those in the controls (P < .001). The methylation levels in TOF cases were correlated with mRNA expression values (r = -0.81, P < .001).

CONCLUSION

The downregulated methylation level at TBX20 promoter may be responsible for the elevated mRNA expression levels in patients with TOF. The abnormal methylation status of the TBX20 promoter may contribute to the pathogenesis of TOF.

Association between MDR1 gene polymorphism and clinical course of pediatric pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease with a complex pathogenesis. The polymorphism of the gene of multidrug resistance-1 (MDR1) has been associated with many diseases including PAH.

Objective. In this study we aimed to investigate the relevance of the MDR1 polymorphism to pediatric PAH clinical course.

Methods. A total of 40 pediatric patients with PAH (secondary to congenital heart defects or idiopathic) and 40 control subjects were enrolled. Patients with PAH were divided into 2 groups, according to their evolution: 28 patients who remained clinically stable at 12-months (non-worsening group) and 12 patients who presented clinical worsening at 12-months (worsening group). Genomic DNA was genotyped for MDR1 gene polymorphisms as follows: C1236T, G2677T and C3435T.

Results. There were no significant differences between PAH children groups (clinical worsening and non-worsening) nor between PAH children and controls in terms of frequency distribution of the three studied genotypes or alleles.

Conclusions. The MDR1 polymorphism could not be correlated with the clinical evolution of pediatric PAH patients in our study.

Uric acid: a potent molecular contributor to pluripotent stem cell cardiac differentiation via mesoderm specification

Congenital heart disease (CHD) is the most common cause of congenital anomaly and a leading cause of morbidity and mortality worldwide. Generation of cardiomyoctyes derived from pluripotent stem cells (PSCs) has opened new avenues for investigation of human cardiac development. Here we report that uric acid (UA), a physiologically abundant compound during embryonic development, can consistently and robustly enhance cardiac differentiation of human PSCs including hESCs and hiPSCs, in replacement of ascorbic acid (AA). We optimized treatment conditions and demonstrate that differentiation day 0–2, a period for specification of mesoderm cells, was a critical time for UA effects. This was further confirmed by UA-induced upregulation of mesodermal markers. Furthermore, we show that the developing mesoderm may be by directly promoted by SNAI pathway-mediated epithelial–mesenchymal transition (EMT) at 0–24 h and a lengthened G0/G1 phase by increasing the ubiquitination degradation in 24–48 h. These findings demonstrate that UA plays a critical role in mesoderm differentiation, and its level might be a useful indicator for CHD in early fetal ultrasound screening.

Novel Point Mutations in the NKX2.5 Gene in Pediatric Patients with Non-Familial Congenital Heart Disease

Background and objective: Congenital heart disease (CHD) is the most common birth abnormality in the structure or function of the heart that affects approximately 1% of all newborns. Despite its prevalence and clinical importance, the etiology of CHD remains mainly unknown. Somatic and germline mutations in cardiac specific transcription factor genes have been identified as the factors responsible for various forms of CHD, particularly ventricular septal defects (VSDs), tetralogy of Fallot (TOF), and atrial septal defects (ASDs). p. NKX2.5 is a homeodomain protein that controls many of the physiological processes in cardiac development including specification and proliferation of cardiac precursors. The aim of our study was to evaluate the NKX2.5 gene mutations in sporadic pediatric patients with clinical diagnosis of congenital heart malformations. Materials and methods: In this study, we investigated mutations of the NKX2.5 gene’s coding region in 105 Iranian pediatric patients with non-familial CHD by polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) and direct sequencing. Results: We observed a total of four mutations, of which, two were novel DNA sequence variants in the coding region of exon 1 (c. 95 A > T and c. 93 A > T) and two others were previously reported as single-nucleotide polymorphisms (SNPs), namely rs72554028 (c. 2357 G > A) and rs3729753 (c. 606 G > C) in exon 2. Further, observed mutations are completely absent in normal healthy individuals (n = 92). Conclusion: These results suggest that NKX2.5 mutations are highly rare in CHD patients. However, in silico analysis proves that c.95 A > T missense mutation in NKX2.5 gene is probably pathogenic and may be contributing to the risk of sporadic CHD in the Iranian population.

Identification of a novel non-sense mutation in TBX5 gene in pediatric patients with congenital heart defects

Introduction: Congenital heart diseases (CHDs) are structural cardiovascular malformations that arise from abnormal development of the heart during the prenatal life. Mutations in the TBX5 gene, encoding T-box transcription factor, are a major cause of CHD. To evaluate the TBX5 mutations in hotspot exons in sporadic pediatric patients with CHD phenotypes, analytical case/control study performed in an Iranian cohort of unrelated patients with clinical diagnosis of congenital heart malformations. Methods: We investigated TBX5 coding exons 4, 5, 6 and 7 in 95 sporadic patients with CHD phenotypes and compared to 82 healthy controls using PCR-SSCP and DNA sequencing approaches. Results: We report here on a novel and heterozygote Non-sense mutation in exon 5 of TBX5, E128X (G14742T), in two Iranian children. This mutation locates inside the T-box and both of pediatric patients carrying this novel mutation suffer from severe heart malformations. The G14742T mutation leads to the substitution of glutamic acid (E) by stop codon (X) at residue 128, an evolutionarily conserved position in T-box as well as in other species. The non-sense mutation of E128X was predicted to be pathogenic by Mutation Taster and Polyphen software programs. Conclusion: TBX5 E128X mutation results in a translational premature stop. This type of mutation results in a shortened protein that may function improperly and which cannot bind to other transcription factors; therefore, haploinsufficiency of TBX5 protein is presumably causing the severe cardiac malformations in these patients.

A Screening Approach to Identify Clinically Actionable Variants Causing Congenital Heart Disease in Exome Data

BACKGROUND

Congenital heart disease (CHD)-structural abnormalities of the heart that arise during embryonic development-is the most common inborn malformation, affecting ≤1% of the population. However, currently, only a minority of cases can be explained by genetic abnormalities. The goal of this study was to identify disease-causal genetic variants in 30 families affected by CHD.

METHODS

Whole-exome sequencing was performed with the DNA of multiple family members. We utilized a 2-tiered whole-exome variant screening and interpretation procedure. First, we manually curated a high-confidence list of 90 genes known to cause CHD in humans, identified predicted damaging variants in genes on this list, and rated their pathogenicity using American College of Medical Genetics and Genomics-Association for Molecular Pathology guidelines.

RESULTS

In 3 families (10%), we found pathogenic variants in known CHD genes TBX5, TFAP2B, and PTPN11, explaining the cardiac lesions. Second, exomes were comprehensively analyzed to identify additional predicted damaging variants that segregate with disease in CHD candidate genes. In 10 additional families (33%), likely disease-causal variants were uncovered in PBX1, CNOT1, ZFP36L2, TEK, USP34, UPF2, KDM5A, KMT2C, TIE1, TEAD2, and FLT4.

CONCLUSIONS

The pathogenesis of CHD could be explained using our high-confidence CHD gene list for variant filtering in a subset of cases. Furthermore, our unbiased screening procedure of family exomes implicates additional genes and variants in the pathogenesis of CHD, which suggest themselves for functional validation. This 2-tiered approach provides a means of (1) identifying clinically actionable variants and (2) identifying additional disease-causal genes, both of which are essential for improving the molecular diagnosis of CHD.

Association of Cx43 rs2071166 polymorphism with an increased risk for atrial septal defect

Atrial septal defect is one of the most common CHD. The pathogenesis of atrial septal defect still remains unknown. Cx43 is the most prevalent connexin in the mammalian heart during development. Its genetic variants can cause several CHD. The aim of our study was to investigate the association of genetic variations of the Cx43 with sporadic atrial septal defect. A total of 450 paediatric patients were recruited, including 150 cases with atrial septal defect and 300 healthy controls. The promoter region of Cx43 was analysed by sequencing after polymerase chain reaction. All data were analysed by using the Statistic Package for Social Science 19.0 software. The frequency of the single nucleotide polymorphism rs2071166 was significantly higher in atrial septal defect cases than in healthy controls. The CC genotype at rs2071166 site in Cx43 was correlated with an increased risk for atrial septal defect (p<0.0001, odds ratio=3.891, 95% confidence interval 1.948-7.772) and the C allele was positively correlated with atrial septal defect (p=0.007, odds ratio=1.567, 95% confidence interval 1.129-2.175). In conclusion, our results confirmed that rs2071166 in Cx43 may be relevant with an increased atrial septal defect risk.

Computational modeling suggests impaired interactions between NKX2.5 and GATA4 in individuals carrying a novel pathogenic D16N NKX2.5 mutation

NKX2.5, a homeobox containing gene, plays an important role in embryonic heart development and associated mutations are linked with various cardiac abnormalities. We sequenced the NKX2.5 gene in 100 congenital heart disease (CHD) patients and 200 controls. Our analysis revealed a total of 7 mutations, 3 in intronic region, 3 in coding region and 1 in 3’ UTR. Of the above mutations, one mutation was found to be associated with tetralogy of fallot (TOF) and two (rs2277923 and a novel mutation, D16N) were strongly associated with VSD. A novel missense mutation, D16N (p-value =0.009744), located in the tinman (TN) region and associated with ventricular septal defect (VSD), is the most significant findings of this study. Computational analysis revealed that D16N mutation is pathogenic in nature. Through the molecular modeling, docking and molecular dynamics simulation studies, we have identified the location of mutant D16N in NKX2.5 and its interaction map with other partners at the atomic level. We found NKX2.5-GATA4 complex is stable, however, in case of mutant we observed significant conformational changes and loss of key polar interactions, which might be a cause of the pathogenic behavior. This study underscores the structural basis of D16N pathogenic mutation in the regulation of NKX2.5 and how this mutation renders the structural-functional divergence that possibly leading towards the diseased state.