c.620C>T mutation in GATA4 is associated with congenital heart disease in South India

Conotruncal Heart Defects: A Narrative Review of Molecular Genetics, Genomics Research and Innovation

Congenital heart defects (CHDs) are most prevalent cardiac defects that occur at birth, leading to significant neonatal mortality and morbidity, especially in the developing nations. Among the CHDs, conotruncal heart defects (CTDs) are particularly noteworthy, comprising a significant portion of congenital cardiac anomalies. While advances in imaging and surgical techniques have improved the diagnosis, prognosis, and management of CTDs, their molecular genetics and genomic substrates remain incompletely understood. This expert review covers the recent advances from January 2016 onward and examines the complexities surrounding the genetic etiologies, prevalence, embryology, diagnosis, and clinical management of CTDs. We also emphasize the known copy number variants and single nucleotide variants associated with CTDs, along with the current planetary health research efforts aimed at CTDs in large cohort studies. In all, this comprehensive narrative review of molecular genetics and genomics research and innovation on CTDs draws from and highlights selected works from around the world and offers new ideas for advances in CTD diagnosis, precision medicine interventions, and accurate assessment of prognosis and recurrence risks.

Alternative splicing signatures of congenital heart disease and induced pluripotent stem cell-derived cardiomyocytes from congenital heart disease patients

Congenital heart disease (CHD) is the most serious congenital defect in newborns with higher mortality. Alternative splicing (AS) plays an essential role in numerous heart diseases. However, our understanding of the link between mRNA splicing and CHD in humans is limited. Here, we try to investigate the genome-wide AS events in CHD using bioinformatics methods. We collected available RNA-seq datasets of CHD-induced pluripotent stem cell-cardiomyocytes (iPSC-CMs) (including single ventricle disease [SVD] and tetralogy of Fallot [TOF]) and non-CHD from the Gene Expression Omnibus database. Then, we unprecedentedly performed AS profiles in CHD-iPSC-CMs and non-CHD-iPSC-CMs. The rMAPS was used to generate RNA-maps for the analysis of RNA-binding proteins' (RBPs) binding sites. We used StringTie to identify and quantify the transcripts from aligned RNA-Seq reads. A quantification matrix was generated with respect to different groups by extracting the transcripts per million values from StringTie outputs. Then, this matrix was used for correlation analysis between the expression level of RBP and AS level. Finally, we validated our AS results using RNA-seq data from CHD and non-CHD patient tissue samples. We identified CHD-related AS events using CHD-iPSC-CMs and CHD samples from patients. The results showed that functional enrichment of abnormal AS in SVD and TOF was transcription factor-related. Using rMAPS, RNA-binding proteins which regulated these AS were also determined, and RBP-AS regulatory network was constructed. Overall, we identified abnormal AS in CHD-iPSC-CMs and CHD samples from patients. We predicted AS regulators in SVD and TOF, respectively. At last, we concluded that AS played a key role in the pathogenesis of CHD.

High-risk genes involved in common septal defects of congenital heart disease

The septation defect is one of the main categories of congenital heart disease (CHD). They can affect the septation of the atria leading to atrial septal defect (ASD), septation of ventricles leading to ventricular septal defect (VSD), and formation of the central part of the heart leading to atrioventricular septal defect (AVSD). Disruption of critical genetic factors involved in the proper development of the heart structure leads to CHD manifestation. Because of this, to identify the high-risk genes involved in common septal defects, a comprehensive search of the literature with the help of databases and the WebGestalt analysis tool was performed. The high-risk genes identified in the analysis were checked in 16 Indian whole-exome sequenced samples, including 13 VSD and three Tetralogy of Fallot for in silico validation. This data revealed three variations in GATA4, i.e., c.C1223A at exon 6: c.C602A and c.C1220A at exon 7; and one variation in MYH6, i.e., c.G3883C at exon 28 in two VSD cases. This study supports previously published studies that suggested GATA4 and MYH6 as the high-risk genes responsible for septal defects. Thus, this study contributes to a better understanding of the genes involved in heart development by identifying the high-risk genes and interacting proteins in the pathway.

In silico analysis of GATA4 variants demonstrates main contribution to congenital heart disease

Introduction: Congenital heart disease (CHD) is the most common congenital abnormality and the main cause of infant mortality worldwide. Some of the mutations that occur in the GATA4 gene region may result in different types of CHD. Here, we report our in silico analysis of gene variants to determine the effects of the GATA4 gene on the development of CHD.

Methods: Online 1000 Genomes Project, ExAC, gnomAD, GO-ESP, TOPMed, Iranome, GME, ClinVar, and HGMD databases were drawn upon to collect information on all the reported GATA4 variations.The functional importance of the genetic variants was assessed by using SIFT, MutationTaster, CADD,PolyPhen-2, PROVEAN, and GERP prediction tools. Thereafter, network analysis of the GATA4protein via STRING, normal/mutant protein structure prediction via HOPE and I-TASSER, and phylogenetic assessment of the GATA4 sequence alignment via ClustalW were performed.

Results: The most frequent variant was c.874T>C (45.58%), which was reported in Germany.Ventricular septal defect was the most frequent type of CHD. Out of all the reported variants of GATA4,38 variants were pathogenic. A high level of pathogenicity was shown for p.Gly221Arg (CADD score=31), which was further analyzed.

Conclusion: The GATA4 gene plays a significant role in CHD; we, therefore, suggest that it be accorded priority in CHD genetic screening.

Novel Point Mutations in 3'-Untranslated Region of GATA4 Gene Are Associated with Sporadic Non-syndromic Atrial and Ventricular Septal Defects

OBJECTIVE

Transcription factor GATA4 has significant roles in embryonic heart development. Mutations of GATA4 appear to be responsible for a wide variety of congenital heart defects (CHD). Despite the high prevalence of GATA4 mutations in CHD phenotypes, extensive studies have not been performed. The 3'-untranslated region (3'-UTR) of the GATA4 gene comprises regulatory motifs and microRNA binding sites that are critical for the appropriate gene expression, nuclear transportation, and regulation of translation, and stability of mRNA. This study aimed to evaluate the association between mutations in the 3'-UTR of the GATA4 gene and CHD risk among Iranian patients.

METHODS

We analyzed the coding region of exon 6 and the whole 3'-UTR of GATA4 in DNA isolated from 175 blood samples of CHD patients and 115 unrelated healthy individuals. The functional importance of the observed GATA4 mutations was evaluated using a variety of bioinformatics algorithms for assessment of nonsynonymous mutations and those observed in miRNA binding sites of 3'-UTR.

RESULTS

Twenty-one point mutations including one missense mutation (c.511A>G: p.Ser377Gly) in exon 6 and 20 nucleotide variations in 3'-UTR of GATA4 gene were identified in 65 of the 175 CHD patients. In our patients, we identified 12 novel sequence alterations and 8 single nucleotide polymorphisms in the 3'-UTR of GATA4. Most of them had statistically significant differences between CHD patients and controls.

CONCLUSION

Our results suggest that 3'-UTR variations of the GATA4 gene probably change microRNA binding sites and present an additional molecular risk factor for the susceptibility of CHD.

The M310T mutation in the GATA4 gene is a novel pathogenic target of the familial atrial septal defect

BACKGROUND

Although most cases of atrial septal defect (ASD) are sporadic, familial cases have been reported, which may be caused by mutation of transcription factor GATA binding protein 4 (GATA4). Herein we combined whole-exome sequencing and bioinformatics strategies to identify a novel mutation in GATA4 accounting for the etiology in a Chinese family with ASD.

METHODS

We identified kindred spanning 3 generations in which 3 of 12 (25.0%) individuals had ASD. Punctilious records for the subjects included complete physical examination, transthoracic echocardiography, electrocardiograph and surgical confirming. Whole-exome capture and high-throughput sequencing were performed on the proband III.1. Sanger sequencing was used to validate the candidate variants, and segregation analyses were performed in the family members.

RESULTS

Direct sequencing of GATA4 from the genomic DNA of family members identified a T-to-C transition at nucleotide 929 in exon 5 that predicted a methionine to threonine substitution at codon 310 (M310T) in the nuclear localization signal (NLS) region. Two affected members (II.2 and III.3) and the proband (III.1) who was recognized as a carrier exhibited this mutation, whereas the other unaffected family members or control individuals did not. More importantly, the mutation GATA4 (c.T929C: p.M310T) has not been reported previously in either familial or sporadic cases of congenital heart defects (CHD).

CONCLUSIONS

We identified for the first time a novel M310T mutation in the GATA4 gene that is located in the NLS region and leads to family ASD with arrhythmias. However, the mechanism by which this pathogenic mutation contributes to the development of heart defect and tachyarrhythmias remains to be ascertained.

GATA 4 Deletions Associated with Congenital Heart Diseases in South Brazil

The normal development of the heart comprises a highly regulated machinery of genetic events, involving transcriptional factors. Congenital heart disease (CHD), have been associated with chromosomal abnormalities and copy number variants (CNVs). Our goal was to investigate through the multiplex ligation-dependent probe amplification (MLPA) technique, the presence of CNVs in reference genes for normal cardiac development in patients with CHD. GATA4 , NKX2-5 , TBX5 , BMP4 , and CRELD1 genes and 22q11.2 chromosome region were analyzed in 207 children with CHD admitted for the first time in a cardiac intensive care unit from a pediatric hospital. CNVs were detected in seven patients (3.4%): four had a 22q11.2 deletion (22q11DS) (1.9%), two had a GATA4 deletion (1%) and one had a 22q11.2 duplication (0.5%). No patients with CNVs in the NKX2-5 , TBX5 , BMP4 , and CRELD1 genes were identified. GATA4 deletions appear to be present in a significant number of CHD patients, especially those with septal defects, persistent left superior vena cava, pulmonary artery abnormalities, and extracardiac findings. GATA4 screening seems to be more effective when directed to these CHDs. The investigation of CNVs in GATA4 and 22q11 chromosome region in patients with CHD is important to anticipating the diagnosis, and to contributing to family planning.

Prenatal alcohol exposure induced congenital heart diseases: From bench to bedside

Alcohol consumption is increasing worldwide. Many child-bearing-aged women consume alcohol during pregnancy, intentionally or unintentionally, thereby increasing the potential risk for severe congenital diseases. Congenital heart disease (CHD) is the most common birth defect worldwide and can result from both hereditary and acquired factors. Prenatal alcohol exposure (PAE) is considered a key factor that leads to teratogenesis in CHD and its specific phenotypes, especially defects of the cardiac septa, cardiac valves, cardiac canals, and great arteries, adjacent to the chambers, both in animal experiments and clinical retrospective studies. The mechanisms underlying CHD and its phenotypes caused by PAE are associated with changes in retinoic acid biosynthesis and its signaling pathway, apoptosis and defective function of cardiac neural crest cells, disturbance of the Wntβ-catenin signaling pathway, suppression of bone morphogenetic protein (BMP) signaling, and other epigenetic mechanisms. Drug supplements and early diagnosis can help prevent PAE from inducing CHDs.

Association of NKX2-5, GATA4, and TBX5 polymorphisms with congenital heart disease in Egyptian children

Background

Several genes encoding transcription factors are known to be the primary cause of congenital heart disease. NKX2‐5 and GATA4 were the first congenital heart disease–causing genes identified by linkage analysis. This study designed to study the association of five single–nucleotide variants of NKX2‐5, GATA4, and TBX5 genes with sporadic nonsyndromic cases of a congenital cardiac septal defect in Egyptian children.

Methods

Venous blood samples from 150 congenital heart disease children (including a ventricular septal defect, atrial septal defect, tetralogy of Fallot, and patent ductus arteriosus) and 90 apparently healthy of matched age and sex were studied by polymerase chain reaction followed by direct sequencing in order to study two single–nucleotide variants of NKX2‐5 (rs2277923, rs28936670), two single–nucleotide variants of GATA4 (rs368418329, rs56166237) and one single–nucleotide variant TBX5 (rs6489957). The distribution of genotype and allele frequency in the congenital heart diseases (CHD) group and control group were analyzed.

Results

We found different genotype frequencies of the two variants of NKX2‐5, as CT genotype of rs2277923 was present in 58% and 36% in cases and control respectively, and TT genotype present in 6% of the cases. Also regarding missense variant rs28936670, heterozygous AG presented in 82% of the cases. Also, we observed a five prime UTR variant rs368418329, GT (42% of the cases) and GG (46% of the cases) genotypes showed the most frequent presentation in cases. While regarding a synonymous variant rs56166237, GT and GG were the most presented in cases (41.4%, 56% respectively) in contrast to control group (20%, 1.7% respectively). Also, a synonymous variant in TBX5, the distribution of genotype frequency was significantly different between the CHD group and control group. CT genotype of TBX5 ‐rs6489957 was found in 12 ASD, 24 VSD, six PDA, three aortic coarctation and nine fallot that represent 42% of the cases.

Conclusions

Significantly higher frequency of different allelle of five variants was observed in cases when compared to the control group, with significant risky effect for the development of septal defect. In addition to two polymorphisms of NKX2‐5 (rs2277923, rs28936670) variant in the cardiac septal defect, two variants in GATA4 (rs368418329, rs56166237) and one variant in TBX5 (rs6489957) seem to have a role in the pathogenesis of congenital heart disease.

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.

Identification of Two Mutations in PCDHGA4 and SLFN14 Genes in an Atrial Septal Defect Family

Atrial septal defect (ASD) is a common acyanotic congenital cardiac disorder associated with genetic mutations. The objective of this study was to identify the genetic factors in a Chinese family with ASD patients by a whole exome sequencing approach. Causative ASD gene mutations were examined in 16 members from a three-generation family, among which 6 individuals were diagnosed as having ASD. One hundred and eighty-three unrelated healthy Chinese were recruited as a normal control group. Peripheral venous blood was collected from every subject for genetic analysis. Exome sequencing was performed in the ASD patients. Potential causal mutations were detected in non-ASD family members and normal controls by polymerase chain reaction and sequencing analysis. The results showed that all affected family members carried two novel compound mutations, c.1187delT of PCDHGA4 and c.2557insC of SLFN14, and these two mutations were considered to have synergetic function on ASD. In conclusion, the mutations of c.1187delT of PCDHGA4 and c.2557insC of SLFN14 may be pathogenic factors contributing to the development of ASD.

Let-7a regulates expression of β1-adrenoceptors and forms a negative feedback circuit with the β1-adrenoceptor signaling pathway in chronic ischemic heart failure

BACKGROUND

The aim of the present study was to investigate the role of microRNA (miRNA) let-7a in down-regulation of β1-adrenoceptors (β1-AR) and elucidate the underlying mechanism of chronic ischemia heart failure (CIHF) in rats.

METHODS AND RESULTS

CIHF model was established by occlusion of coronary artery for 4 weeks. β1-AR level was obviously down-regulated and let-7a up-regulated in the failing heart 4 weeks after myocardial infarction. Overexpression of let-7a inhibited β1-AR expression in neonatal rat ventricular cells (NRVCs), which was abolished by anti-let-7a antisense inhibitor. The lentivirus vector containing precursor let-7a (len-pre-let-7a) further down-regulated the reduced β1-AR level by CIHF and the effect was reversed by len-AMO-let-7a. Len-negative control did not produce any significant influence on β1-AR expression. Importantly, there exists a negative feedback loop associated with β1-AR regulation through β1-AR/cAMP/PKA/GATA4/let-7a/β1-AR signaling pathway in CIHF. As demonstrated, GATA4 was activated by β1-AR up-regulation through cAMP-PKA signaling pathway in early phase of ischemia, then GATA4 positively regulated let-7a expression which in turn suppressed β1-AR expression.

CONCLUSIONS

Let-7a regulates β1-AR expression and forms a negative feedback loop with β1-AR signaling pathway in ischemic heart failure. This study provides a new insight into the differential expression of β1-AR in early and later phase of myocardial ischemia.

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.

Protein-altering and regulatory genetic variants near GATA4 implicated in bicuspid aortic valve

Bicuspid aortic valve (BAV) is a heritable congenital heart defect and an important risk factor for valvulopathy and aortopathy. Here we report a genome-wide association scan of 466 BAV cases and 4,660 age, sex and ethnicity-matched controls with replication in up to 1,326 cases and 8,103 controls. We identify association with a noncoding variant 151 kb from the gene encoding the cardiac-specific transcription factor, GATA4, and near-significance for p.Ser377Gly in GATA4. GATA4 was interrupted by CRISPR-Cas9 in induced pluripotent stem cells from healthy donors. The disruption of GATA4 significantly impaired the transition from endothelial cells into mesenchymal cells, a critical step in heart valve development.

Mutation Screening of Gata4 Gene in CTD Patients Within Chinese Han Population

Conotruncal heart defect is a complex form of congenital heart disease and usually has a poor prognosis. Although previous studies have identified several missense variants in GATA4 gene that may cause CTD, it remains unclear whether they are involved in CTD pathogenesis because the study population was limited. The aim of the study was to investigate the mutations of GATA4 gene in isolated CTD Chinese Han patients and identify the pathomechanism of the missense mutations. In this report, the coding exons and exon-intron boundaries of the GATA4 gene were sequenced in 600 CTD patients and 300 controls. Functional significance of the novel GATA4 gene mutation (p.A167D) was analyzed using PolyPhen 2 and SIFT. And, the functional characteristics of the mutant GATA4 gene were assayed in contrast to its wild-type counterpart using a luciferase reporter assay system as well as Western blot. Eight heterozygous nonsynonymous variants (V380M, G64E, A167D, V267M, S377G, P163S, P407Q, A66T) were found in 22 patients, of which one (A167D) was reported here for the first time and five (G64E, A167D, S377G, P163S, A66T) were only found in CTD patients when compared with 300 controls. The PolyPhen 2 and SIFT programs predicted that the A167D substitution was expected to influence protein function. Subsequent functional analyses revealed that the transcriptional activity and Western blot of A167D mutant GATA4 protein were not altered. These variants may be involved in other mechanisms underlying CTD or may be unrelated to CTD occurrence.

RNA Splicing

RNA splicing represents a post-transcriptional mechanism to generate multiple functional RNAs or proteins from a single transcript. The evolution of RNA splicing is a prime example of the Darwinian function follows form concept. A mutation that leads to a new mRNA (form) that encodes for a new functional protein (function) is likely to be retained, and this way, the genome has gradually evolved to encode for genes with multiple isoforms, thereby creating an enormously diverse transcriptome. Advances in technologies to characterize RNA populations have led to a better understanding of RNA processing in health and disease. In the heart, alternative splicing is increasingly being recognized as an important layer of post-transcriptional gene regulation. Moreover, the recent identification of several cardiac splice factors, such as RNA-binding motif protein 20 and SF3B1, not only provided important insight into the mechanisms underlying alternative splicing but also revealed how these splicing factors impact functional properties of the heart. Here, we review our current knowledge of alternative splicing in the heart, with a particular focus on the major and minor spliceosome, the factors controlling RNA splicing, and the role of alternative splicing in cardiac development and disease.