Novel NKX2-5 Mutation Associated with Familial Atrial Septal Defect and Atrial and Ventricular Arrhythmias

Patients with atrial septal defects (ASDs) have increased mortality and morbidity. This can only partly be explained by hemodynamic changes caused by the ASD, suggesting additional underlying causes. Patients with an ASD have an increased burden of pathogenic gene variants in ASD-related genes, indicating genetics as an important factor in etiology. Inheritance of genetic variants with high impact can cause ASD in relatives (familial ASD). This study aimed to investigate whether lifelong outcomes were different in patients with familial ASD compared with patients with sporadic ASD. We used health registries and a nationwide cohort of 2,151 patients with ASD to compare the incidences of atrial fibrillation or flutter (together abbreviated as AF), heart failure, and mortality between patients with familial and sporadic ASD using Cox proportional hazard ratio and Fine and Gray analysis. Patients with familial ASD experienced AF and heart failure earlier in life than patients with sporadic ASD, with hazard ratios of 1.6 and 1.7, respectively. Subdistribution hazard ratios showed an increased risk of AF and heart failure in patients with familial ASD compared with patients with sporadic ASDs (2.3 and 3.1, respectively). Our results suggest that genetic variants with high impact may influence the outcomes of patients with ASD. In conclusion, patients with familial ASD have an increased risk and an earlier onset of AF and heart failure compared with patients with sporadic ASD, hence clinical awareness of arrhythmias and heart failure in patients with familial ASD may lead to timely treatment.

Secundum atrial septal defect (ASD) is a common congenital heart malformation that occurs as an isolated anomaly in 10% of individuals with congenital heart disease. Although some embryological pathways have been elucidated, the molecular etiologies of ASD are not fully understood. Most cases of ASD are isolated, but some individuals with ASD have a family history of this defect or other congenital heart malformations. Clinical evaluation of three families identified individuals with ASD in multiple generations. ASD was transmitted as an autosomal dominant trait in each family. ASD was the most common anomaly, but other heart defects occurred alone or in association with ASD in individuals from each kindred. Genome-wide linkage studies in one kindred localized a familial ASD disease gene to chromosome 5p (multipoint LOD score=3.6, theta=0.0). Assessment of 20 family members with the disease haplotype revealed that 9 had ASD, 8 were clinically unaffected, and 3 had other cardiac defects (aortic stenosis, atrial septal aneurysm, and persistent left superior vena cava). Familial ASD did not map to chromosome 5p in two other families. Familial ASD is a genetically heterogeneous disorder; one disease gene maps to chromosome 5p. Recognition of the heritable basis of familial ASD is complicated by low disease penetrance and variable expressivity. Identification of ASD or other congenital heart defects in more than one family member should prompt clinical evaluation of all relatives.

ObjectiveAtrial septal defect (ASD) is the second most common congenital heart defect (CHD) and is observed in families as an autosomal dominant trait as well as in nonfamilial CHD. Mutations in the NKX2‐5 gene, located on chromosome 5, are associated with ASD, often combined with conduction disturbances, cardiomyopathies, complex CHD, and sudden cardiac death as well. Here, we show that NKX2‐5 mutations primarily occur in ASD patients with conduction disturbances and heritable ASD. Furthermore, these families are at increased risk of sudden cardiac death.ResultsWe screened 39 probands with familial CHD for mutations in NKX2‐5 and discovered a novel mutation in one family (2.5%) with ASD and atrioventricular block. A review of the literature revealed 59 different NKX2‐5 mutations in 202 patients. Mutations were significantly more common in familial cases compared to nonfamilial cases (P = 7.1 × 10−9). The majority of patients (74%) had ASD with conduction disturbance. Nineteen patients (15%) of 120 with familial ASD and conduction disturbance died from sudden cardiac death of which nine (8%) were confirmed mutation carriers, and 10 were possible carriers.Conclusions NKX2‐5 mutations mainly occur in familial CHD, the signature phenotype is ASD with conduction disturbances and mutation carriers are at increased risk of sudden cardiac death. We suggest that familial ASD patients should be screened for NKX2‐5 mutations and, if they are mutation carriers, implantation of an implantable cardioverter‐defibrillator should be considered in these patients.

ObjectiveAtrial septal defect (ASD) is one of the most common forms of congenital heart disease. Genetic defects play important roles in the pathogenesis of ASD but are complex and unclear. This study tries to discover the genetic pathogenesis in familial and sporadic ASD patients.MethodsIn Stage I, in a family with 30 members whole exome sequencing was performed in 4 ASD patients and the identified genetic variants were screened in the rest of the family members. In Stage II, 335 unrelated sporadic and isolated ASD patients were enrolled to test whether the genetic variants were involved in these patients. In Stage III, biological functions of the variants were elucidated at the cellular level and the CRISPR/Cas9 was used to construct variant‐specific mutant mice in order to observe the abnormality of the heart structure.ResultsA novel heterozygous missense variant, FOXC1 c.518G>A (p.R173H) was identified in the ASD family by whole exome sequencing. Subsequently, other 4 heterozygous variants in FOXC1, including 2 novel missense variants: c.556‐558delAAG (p.K186del) and c.559G>A (p.D187N) were identified in unrelated 335 sporadic ASD patients. In dual‐luciferase reporter assay, the transcriptional activity of R173H decreased to almost 30% of the wild‐type. In the Foxc1 R173H site‐specific mutant mice, the atrial septum became very thin in tissue slices of the heart that was similar to the echocardiographic finding in the above family members.ConclusionVariants in FOXC1 likely cause cardiac anomaly, particularly ASD. These findings provide a new insight into genetic mechanisms and counseling of familial and sporadic ASD.

Atrial septal defect (ASD) is a common cardiovascular malformation and an important contributor to substantial morbidity and mortality. Increasing evidence demonstrates that mutated NKX2-5, a gene encoding a homeobox transcription factor crucial to cardiogenesis, is a significant genetic determinant for congenital ASD. Nevertheless, the genetic basis for ASD in a majority of ASD patients remains largely unknown. In the current study, the entire coding region of NKX2-5 was sequenced initially for 58 unrelated probands with familial ASD. The relatives of the probands harboring identified mutations and 200 unrelated control individuals were subsequently genotyped. Three novel heterozygous NKX2-5 mutations (p.P43GfsX59, p.C46W, and p.S179F) were identified respectively in three families with autosomal dominantly inherited ASD. These mutations, absent in 200 control individuals, cosegregated with ASD in the families that had complete penetrance. The findings expand the spectrum of mutations in NKX2-5 linked to ASD and contribute to genetic counseling, clinical interventions, and prenatal prevention of ASD for individuals with genetic susceptibility.

Recently, GATA4 and NKX2.5 were reported as the disease genes of atrial septal defect (ASD) but the relationship between the locations of their mutations and phenotypes is not clear. We analyzed GATA4 and NKX2.5 mutations in 16 familial ASD cases, including four probands with atrioventricular conduction disturbance (AV block) and two with pulmonary stenosis (PS), by PCR and direct sequencing, and examined their phenotypes clinically. Five mutations, including two GATA4 and three NKX2.5 mutations, were identified in 31.3% of the probands with ASD, and three of them were novel. The two GATA4 mutations in the probands without AV block were S52F and E359Xfs (c.1075delG) that was reported previously, and three NKX2.5 mutations in the probands with AV block were A88Xfs (c.262delG), R190C, and T178M. Additionally, we observed some remarkable phenotypes, i.e., dextrocardia with E359Xfs (c.1075delG) and cribriform type ASD with R190C, both of which are expected to be clues for further investigations. Furthermore, progressive, most severe AV block was closely related with a missense mutation in a homeodomain or with a nonsense/frame-shift mutation of NKX2.5 for which classification has not been clearly proposed. This pinpoints essential sites of NKX2.5 in the development of the conduction system.

Heart-hand syndromes compose a class of combined congenital cardiac and limb deformities. The proto-typical heart-hand disorder is Holt-Oram syndrome, which is characterized by cardiac septation defects and radial ray limb deformity. We have recently mapped the Holt-Oram syndrome gene defect to the long arm of human chromosome 12 in two families. The role of this disease locus in the pathogenesis of related conditions such as heart-hand syndrome type III (cardiac conduction disease accompanied by skeletal malformations) or familial atrial septal defects is unknown. Clinical evaluations and genetic linkage analyses were performed in five additional kindreds with Holt-Oram syndrome and also in one kindred with heart-hand syndrome type III and one kindred with familial atrial septal defect and conduction disease. Holt-Oram syndrome in all five kindreds mapped to chromosome 12q2. These studies and previous data provide odds of greater than 10(25):1 that the Holt-Oram syndrome disease gene is at chromosome 12q2. In contrast, neither the phenotypically similar disorder heart-hand syndrome type III nor the locus responsible for a familial atrial septal defect with atrioventricular block maps to chromosome 12q2. We demonstrate that heart-hand syndromes are genetically heterogeneous. Conditions that clinically appear to be partial phenocopies of Holt-Oram syndrome arise from distinct disease genes.

Aims: Congenital heart disease (CHD) frequently occurs in newborns due to abnormal formation of the heart or major blood vessels. Mutations in the GATA4 gene, which encodes GATA binding protein 4, are responsible for atrial septal defect (ASD), a common CHD. This study aims to gain insights into the molecular mechanisms of CHD using human induced pluripotent stem cells (iPSCs) from a family cohort with ASD. Methods and Results: Patient-specific iPSCs possess the same genetic information as the donor and can differentiate into various cell types from all three germ layers in vitro , thus presenting a promising approach for disease modeling and molecular mechanism research. Here, we generated a patient-specific iPSC line (iPSC-G4 T280M ) from a family cohort carrying a hereditary ASD mutation in GATA4 gene (T280M), as well as a human embryonic stem cell line (ESC-G4 T280M ) carrying the isogenic T280M mutation using the CRISPR/Cas9 genome editing method. The GATA4-mutant iPSCs and ESCs were then differentiated into cardiomyocytes (CMs) to model GATA4 mutation-associated ASD. We observed an obvious defect in cell proliferation in cardiomyocytes derived from both GATA4 T280M -mutant iPSCs (iPSC-G4 T280M -CMs) and ESCs (ESC-G4 T280M -CMs), while the impaired proliferation ability of iPSC-G4 T280M -CMs could be restored by gene correction. Integrated analysis of RNA-Seq and ChIP-Seq data indicated that FGF16 is a direct target of wild-type GATA4. However, the T280M mutation obstructed GATA4 occupancy at the FGF16 promoter region, leading to impaired activation of FGF16 transcription. Overexpression of FGF16 in GATA4-mutant cardiomyocytes rescued the cell proliferation defect. The direct relationship between GATA4 T280M and ASD was demonstrated in a human iPSC model for the first time. Conclusions: In summary, our study revealed the molecular mechanism of the GATA4 T280M mutation in ASD. Understanding the roles of the GATA4-FGF16 axis in iPSC-CMs will shed light on heart development and provide novel insights for the treatment of ASD and other CHD disorders.

Atrial septal defects (ASDs) are the most common form of congenital heart disease. There are 4 embryologic types of ASDs, and rhythm considerations vary based on type. ASDs have left-to-right shunt and primarily right-sided volume overload. This leads to electrical remodeling that may predispose patients to atrial tachyarrhythmias and conduction disorders. Risk for arrhythmias is increased with late age of ASD repair, shunt size, other factors such as pulmonary hypertension and comorbid conditions. Arrhythmia incidence is decreased after ASD closure, but remains elevated compared to general population. Medical and procedural therapy for arrhythmias should consider type and timing of ASD repair. Conduction disorders are rare. Sinus node dysfunction may be seen with late age of repair and large shunt size. Sinus venosus ASD exhibits a higher rate of sinus node dysfunction, especially with older surgical techniques. Ostium primum ASD has higher risk of spontaneous or post-operative AV block, though this is rare with current surgical techniques. Risk of AV block with surgical repair or device closure of secundum ASD is rare. Familial ASDs and other forms of congenital heart disease may be seen with mutations in associated myocardial transcription factors NKX2.5, GATA4, TBX6, along with conduction disorders such as AV block.

A novel mutation of GATA4 in a familial atrial septal defect

A novel NKX2–5 double variant corresponds with familial atrial septal defect with arrhythmia in Indonesia

lettersRe: Consanguinity and isolated atrial septal defect in the North East of Iran Mahmood Dhahir Al-Mendalawi Mahmood Dhahir Al-Mendalawi Search for more papers by this author Published Online:10 Jan 2019https://doi.org/10.5144/0256-4947.2014.270bSectionsPDF ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail AboutIntroductionTo the Editor: I read with interest the study by Moghaddam et al1 on the consanguinity and isolated atrial septal defect (ASD) in the North East of Iran. It is well known that congenital heart diseases (CHDs), particularly ASD, generally tend to follow multifactorial inheritance. However, autosomal dominant inheritance of ASD has been increasingly reported.2,3 This genetic form of inheritance together with the fact that consanguinity increases the risk of couples to have offspring with CHDs could result in the familial aggregation of ASD. It is expected for the familial aggregation of ASD to be prevailed in Iran. This is based on the following 3 points. (1) Among various types of CHDs, ASD has been reported to be predominant in Iran.4 (2) Consanguineous marriage is culturally preferable in Iran, and its trend has been noticed to be significantly on rise.5 (3) A total of 44% of ASD patients in the study by Moghaddam et al1 had parents with either the third-degree relationship or far relationship. Since associated cardiac, atrioventricular conduction, and skeletal anomalies are not uncommon in ASD, and in the view of potentially high occurrence of familial ASD in Iran based on the aforementioned 3 points, I presume that large-scale multicenter studies are needed to verify the requirement to screen ASD parents and their first-degree and second-degree relatives for associated anomalies.ARTICLE REFERENCES:1. Moghaddam HM, Esfehani RJ, Panah NY, Esfehani AJ. "Consanguinity and isolated atrial septal defect in North East of Iran" . Ann Saudi Med. 2014; 34(2):147-52. Google Scholar2. Li Volti S, Distefano G, Garozzo R, Romeo MG, Sciacca P, Mollica F. "Autosomal dominant atrial septal defect of ostium secundum type. Report of three families" . Ann Genet. 1991; 34:14-8. Google Scholar3. Mandorla S1, Martino C. "Familial atrial septal defect with atrioventricular conduction defects" . G Ital Cardiol. 1998; 28:294-6. Google Scholar4. Nikyar B, Sedehi M, Mirfazeli A, Qorbani M, Golalipour MJ. "Prevalence and Pattern of Congenital Heart Disease among Neonates in Gorgan, Northern Iran (2007–2008)" . Iran J Pediatr. 2011; 21:307-12. Google Scholar5. Akrami SM, Montazeri V, Shomali SR, Heshmat R, Larijani B. "Is there a significant trend in prevalence of consanguineous marriage in Tehran? A review of three generations" . J Genet Couns. 2009; 18:82-6. Google Scholar Previous article Next article FiguresReferencesRelatedDetails Volume 34, Issue 3May-June 2014 Metrics History Published online10 January 2019 InformationCopyright © 2014, Annals of Saudi MedicineThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.PDF download

Congenital heart disease (CHD) frequently occurs in newborns due to abnormal formation of the heart or major blood vessels. Mutations in the GATA4 gene, which encodes GATA binding protein 4, are responsible for atrial septal defect (ASD), a common CHD. This study aims to gain insights into the molecular mechanisms of CHD using human-induced pluripotent stem cells (iPSCs) from a family cohort with ASD. Patient-specific iPSCs possess the same genetic information as the donor and can differentiate into various cell types from all three germ layers in vitro, thus presenting a promising approach for disease modelling and molecular mechanism research. Here, we generated a patient-specific iPSC line (iPSC-G4T280M) from a family cohort carrying a hereditary ASD mutation in GATA4 gene (T280M), as well as a human embryonic stem cell line (ESC-G4T280M) carrying the isogenic T280M mutation using the CRISPR/Cas9 genome editing method. The GATA4-mutant iPSCs and ESCs were then differentiated into cardiomyocytes (CMs) to model GATA4 mutation-associated ASD. We observed an obvious defect in cell proliferation in cardiomyocytes derived from both GATA4T280M-mutant iPSCs (iPSC-G4T280M-CMs) and ESCs (ESC-G4T280M-CMs), while the impaired proliferation ability of iPSC-G4T280M-CMs could be restored by gene correction. Integrated analysis of RNA-Seq and ChIP-Seq data indicated that FGF16 is a direct target of wild-type GATA4. However, the T280M mutation obstructed GATA4 occupancy at the FGF16 promoter region, leading to impaired activation of FGF16 transcription. Overexpression of FGF16 in GATA4-mutant cardiomyocytes rescued the cell proliferation defect. The direct relationship between GATA4T280M and ASD was demonstrated in a human iPSC model for the first time. In summary, our study revealed the molecular mechanism of the GATA4T280M mutation in ASD. Understanding the roles of the GATA4-FGF16 axis in iPSC-CMs will shed light on heart development and provide novel insights for the treatment of ASD and other CHD disorders.

Atrial septal defect (ASD) of the fossa ovalis type was found in 16 members of one family and confirmed in 15 members at autopsy or surgery or by cardiac catheterization. Sinus rhythm was present in 12 affected members, 11 of whom had electrocardiographic evidence of prolonged atrioventricular (A-V) conduction. Five other family members without ASD also had prolonged A-V conduction. The pedigree chart suggests that the syndrome ASD with prolonged A-V conduction is the manifestation of a single mutant autosomal gene with dominant effect, a high degree of penetrance, and some variation in expressivity. Earlier reports of familial ASD showing the autosomal-dominant pattern of inheritance reveal a similar frequency of prolonged A-V conduction among affected persons. The great majority of cases of ASD are sporadic, with little likelihood of recurrence in subsequent sibs or children. We suggest, however, that when ASD of the fossa ovalis type is accompanied by prolonged A-V conduction, the genetic prognosis may be drastically changed to a risk of almost 50% that the condition will recur in subsequent sibs or children of affected persons.

Familial atrial septal defect (ASD) has previously been attributed primarily to mutations in cardiac transcription factors. Here, we report a large, multi-generational family (78 members) with ASD combined with a late-onset dilated cardiomyopathy and further characterize the consequences of mutant α-actin. We combined a genome-wide linkage analysis with cell biology, microscopy, and molecular biology tools to characterize a novel ACTC1 (cardiac α-actin) mutation identified in association with ASD and late-onset dilated cardiomyopathy in a large, multi-generational family. Using a genome-wide linkage analysis, the ASD disease locus was mapped to chromosome 15q14 harboring the ACTC1 gene. In 15 affected family members, a heterozygous, nonsynonymous, and fully penetrant mutation (p. Gly247Asp) was identified in exon 5 of ACTC1 that was absent in all healthy family members (n=63). In silico tools predicted deleterious consequences of this variant that was found absent in control databases. Ultrastructural analysis of myocardial tissue of one of the mutation carriers showed sarcomeric disarray, myofibrillar degeneration, and increased apoptosis, while cardiac proteomics revealed a significant increase in extracellular matrix proteins. Consistently, structural defects and increased apoptosis were also observed in neonatal rat ventricular cardiomyocytes overexpressing the mutant, but not native human ACTC1. Molecular dynamics studies and additional mechanistic analyses in cardiomyocytes confirmed actin polymerization/turnover defects, thereby affecting contractility. A combined phenotype of ASD and late-onset heart failure was caused by a heterozygous, nonsynonymous ACTC1 mutation. Mechanistically, we found a shared molecular mechanism of defective actin signaling and polymerization in both cardiac development and contractile function. Detection of ACTC1 mutations in patients with ASD may thus have further clinical implications with regard to monitoring for (late-onset) dilated cardiomyopathy.