Mutations in VEGFA are associated with congenital left ventricular outflow tract obstruction

Whole exome sequencing reveals genetic landscape associated with left ventricular outflow tract obstruction in Chinese Han population

Left ventricular outflow tract obstruction (LVOTO), a major form of outflow tract malformation, accounts for a substantial portion of congenital heart defects (CHDs). Unlike its prevalence, the genetic architecture of LVOTO remains largely unknown. To unveil the genetic mutations and risk genes potentially associated with LVOTO, we enrolled a cohort of 106 LVOTO patients and 100 healthy controls and performed a whole-exome sequencing (WES). 71,430 rare deleterious mutations were found in LVOTO patients. By using gene-based burden testing, we further found 32 candidate genes enriched in LVOTO patient including known pathological genes such as GATA5 and GATA6. Most variants of 32 risk genes occur simultaneously rather exclusively suggesting polygenic inherence of LVOTO and 14 genes out of 32 risk genes interact with previously discovered CHD genes. Single cell RNA-seq further revealed dynamic expressions of GATA5, GATA6, FOXD3 and MYO6 in endocardium and neural crest lineage indicating the mutations of these genes lead to LVOTO possibly through different lineages. These findings uncover the genetic architecture of LVOTO which advances the current understanding of LVOTO genetics.

Congenital aortic valve stenosis: from pathophysiology to molecular genetics and the need for novel therapeutics

Congenital aortic valve stenosis (AVS) is one of the most common valve anomalies and accounts for 3%-6% of cardiac malformations. As congenital AVS is often progressive, many patients, both children and adults, require transcatheter or surgical intervention throughout their lives. While the mechanisms of degenerative aortic valve disease in the adult population are partially described, the pathophysiology of adult AVS is different from congenital AVS in children as epigenetic and environmental risk factors play a significant role in manifestations of aortic valve disease in adults. Despite increased understanding of genetic basis of congenital aortic valve disease such as bicuspid aortic valve, the etiology and underlying mechanisms of congenital AVS in infants and children remain unknown. Herein, we review the pathophysiology of congenitally stenotic aortic valves and their natural history and disease course along with current management strategies. With the rapid expansion of knowledge of genetic origins of congenital heart defects, we also summarize the literature on the genetic contributors to congenital AVS. Further, this increased molecular understanding has led to the expansion of animal models with congenital aortic valve anomalies. Finally, we discuss the potential to develop novel therapeutics for congenital AVS that expand on integration of these molecular and genetic advances.

Identification of a De Novo LRP1 mutation in a Saudi Family with Tetralogy of Fallot

BACKGROUND

Tetralogy of Fallot (TOF) is a rare, complex congenital heart defect caused by genetic and environmental interactions that results in abnormal heart development during the early stages of pregnancy. Genetic basis of TOF in Saudi populations is not yet studied. Therefore, the objective of this study is to screen for the molecular defects causing TOF in Saudi patients.

METHODS

A family with non-syndromic TOF was recruited from the Western region of Saudi Arabia. Whole exome sequencing (WES) was performed on the proband and her parents. The identified candidate variant was verified by sanger sequencing. Also, different computational biology tools were used to figure out how candidate variants affect the structure and function of candidate protein involved in TOF.

RESULTS

A novel heterozygous de novo mutation in LRP1 (p. G3311D) gene was identified in the index case. Also, this variant was absent in the in-house exome sequencing data of 80 healthy Saudi individuals. This variant was predicted to be likely pathogenic, as it negatively affects the biophysical chemical properties and stability of the protein. Furthermore, functional biology data from knock out mouse models confirms that molecular defects in LRP1 gene leads to cardiac defects and lethality. This variant was not previously reported in both Arab and global population genetic databases.

CONCLUSION

The findings in this study postulate that the LRP1 variant has a role in TOF pathogenesis and facilitate accurate diagnosis as well as the understanding of underlying molecular mechanisms and pathophysiology of the disease.

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.

Genetic and epigenetic mechanisms in the development of congenital heart diseases

Congenital heart disease (CHD) is the most common of congenital cardiovascular malformations associated with birth defects, and it results in significant morbidity and mortality worldwide. The classification of CHD is still elusive owing to the complex pathogenesis of CHD. Advances in molecular medicine have revealed the genetic basis of some heart anomalies. Genes associated with CHD might be modulated by various epigenetic factors. Thus, the genetic and epigenetic factors are gradually accepted as important triggers in the pathogenesis of CHD. However, few literatures have comprehensively elaborated the genetic and epigenetic mechanisms of CHD. This review focuses on the etiology of CHD from genetics and epigenetics to discuss the role of these factors in the development of CHD. The interactions between genetic and epigenetic in the pathogenesis of CHD are also elaborated. Chromosome abnormalities and gene mutations in genetics, and DNA methylations, histone modifications and on-coding RNAs in epigenetics are summarized in detail. We hope the summative knowledge of these etiologies may be useful for improved diagnosis and further elucidation of CHD so that morbidity and mortality of children with CHD can be reduced in the near future.

Genetics and Genomics of Pediatric Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease with high mortality despite recent therapeutic advances. The disease is caused by both genetic and environmental factors and likely gene-environment interactions. While PAH can manifest across the lifespan, pediatric-onset disease is particularly challenging because it is frequently associated with a more severe clinical course and comorbidities including lung/heart developmental anomalies. In light of these differences, it is perhaps not surprising that emerging data from genetic studies of pediatric-onset PAH indicate that the genetic basis is different than that of adults. There is a greater genetic burden in children, with rare genetic factors contributing to ~42% of pediatric-onset PAH compared to ~12.5% of adult-onset PAH. De novo variants are frequently associated with PAH in children and contribute to at least 15% of all pediatric cases. The standard of medical care for pediatric PAH patients is based on extrapolations from adult data. However, increased etiologic heterogeneity, poorer prognosis, and increased genetic burden for pediatric-onset PAH calls for a dedicated pediatric research agenda to improve molecular diagnosis and clinical management. A genomics-first approach will improve the understanding of pediatric PAH and how it is related to other rare pediatric genetic disorders.

Association of aminoacyl-tRNA synthetases gene polymorphisms with the risk of congenital heart disease in the Chinese Han population

Aminoacyl-tRNA synthetases (ARSs) are in charge of cellular protein synthesis and have additional domains that function in a versatile manner beyond translation. Eight core ARSs (EPRS, MRS, QRS, RRS, IRS, LRS, KRS, DRS) combined with three nonenzymatic components form a complex known as multisynthetase complex (MSC).We hypothesize that the single-nucleotide polymorphisms (SNPs) of the eight core ARS coding genes might influence the susceptibility of sporadic congenital heart disease (CHD). Thus, we conducted a case-control study of 984 CHD cases and 2953 non-CHD controls in the Chinese Han population to evaluate the associations of 16 potentially functional SNPs within the eight ARS coding genes with the risk of CHD. We observed significant associations with the risk of CHD for rs1061248 [G/A; odds ratio (OR) = 0.90, 95% confidence interval (CI) = 0.81–0.99; P = 3.81×10⁻²], rs2230301 [A/C; OR = 0.73, 95%CI = 0.60–0.90, P = 3.81×10⁻²], rs1061160 [G/A; OR = 1.18, 95%CI = 1.06–1.31; P = 3.53×10⁻³] and rs5030754 [G/A; OR = 1.39, 95%CI = 1.11–1.75; P = 4.47×10⁻³] of EPRS gene. After multiple comparisons, rs1061248 conferred no predisposition to CHD. Additionally, a combined analysis showed a significant dosage-response effect of CHD risk among individuals carrying the different number of risk alleles (P_trend = 5.00×10⁻⁴). Compared with individuals with “0–2” risk allele, those carrying “3”, “4” or “5 or more” risk alleles had a 0.97-, 1.25- or 1.38-fold increased risk of CHD, respectively. These findings indicate that genetic variants of the EPRS gene may influence the individual susceptibility to CHD in the Chinese Han population.

Characterization of transcription factor AP-2 β mutations involved in familial isolated patent ductus arteriosus suggests haploinsufficiency

BACKGROUND

Patent ductus arteriosus (PDA) is one of the most common congenital heart defects. Transcription factor AP-2 beta (TFAP2B) mutations are associated with the Char syndrome, a disorder associated with PDA, and with facial and fingers abnormalities. Recently, we identified two TFAP2B mutations in two families without Char syndrome phenotype, c.601+5G>A and c.435_438delCCGG, and these TFAP2B mutations were associated with familial isolated PDA. The aim of this study was to identify the effects of these mutations on TFAP2B function.

METHODS

Plasmids containing the wild-type or mutated TFAP2B were constructed and transfected in cells. Plasmids containing the TFAP2B coactivator, Cpb/p300-interacting transactivator 2 (CITED2), was also transfected. TFAP2B expression was detected by luciferase expression and by Western blot analysis.

RESULTS

These mutations resulted in loss of transactivation function, which could not be improved by Cpb/p300-interacting transactivator 2. The c.601+5G>A mutated gene did not express any protein, whereas the c.435_438delCCGG mutation did not impact the transactivation function activated by the wild-type TFAP2B.

CONCLUSIONS

These results suggest that a haploinsufficiency effect of TFAP2B could be involved in familial isolated PDA.

Screening of families of patients with left-sided cardiovascular anomalies

BACKGROUND

There is increasing evidence of clustering of certain cardiac anomalies in some families. The frequency and echocardiographic features of such anomalies among the relatives of patients with bicuspid aortic valve (BAV) or other left-sided cardiovascular anomalies (LSCA) were evaluated.

METHODS

The patients with BAV or any other LSCA and their relatives were enrolled in the study. They underwent an echocardiographic examination. The probands were assessed in three groups: BAV, BAV + coarctation of aorta (CoA), and other LSCA. Their relatives were also grouped and evaluated accordingly. The echocardiographic measurements were standardized by Z-scores.

RESULTS

Eighty-six probands and 261 relatives were evaluated. The numbers of the patients in the BAV, BAV + CoA, and other LSCA group were 52, 14, and 20, respectively. Any LSCA was determined in 17 (6.5%) of the relatives. Thirteen (5%) had aortic dilatation and the remainder (1.5%) had BAV. Accordingly, BAV incidence among relatives of patients with BAV was found to be 1.9%. A second individual with an LSCA was observed in 12.8% of 86 families investigated. The frequencies of aortic stenosis, aortic regurgitation, aortic stenosis + aortic regurgitation, and aortic dilatation in the patients with BAV were found to be 37.9%, 53%, 25.8% and 48.5%, respectively. In contrast to previous reports, no enlargement was observed in the pulmonary arteries of BAV patients.

CONCLUSIONS

BAV and other LSCA are of clinical significance. Because the clustering of LSCA in some families is observed, we recommend echocardiographic screening of those relatives. If this is not possible, at least it should be achieved for BAV patients.

Familial congenital heart disease: data collection and preliminary analysis

The aim of this study was to explore genetic mechanisms of congenital heart disease by analysing family data. Families with two or more affected members were studied, and information on family history and risk factors was collected. A total of 25 families with congenital heart disease were identified, and among them the condition was confirmed in 57. The prevalence of congenital heart disease in first-degree relatives was 43.0%, that is 46 out of 107, significantly higher than that in second-degree relatives, that is, 4.4%, 11 out of 252) (χ2 = 83.897, P < 0.01). The prevalence difference between twins (90%) and siblings (62.2%) (χ2 = 4.983, P < 0.05) was also significant among first-degree relatives. Eleven families were found to have the same phenotype (44%), including ventricular septal defect in six families, atrial septal defect in two families, conotruncal defects in two families, and hypoplastic left heart syndrome in one family. Both twins were diagnosed with congenital heart disease in 8 out of 10 twin families - all eight twins were monozygotic. The cardiac phenotype of the twins was consistent in three families (37.5%). The cardiac phenotype of first- and second-degree relatives was not fully consistent with their probands. There was an increased incidence of threatened abortion in early pregnancy in patients with familial congenital heart disease when compared with sporadic congenital heart disease (χ2 = 8.704, P < 0.05). Morbidity in relatives was related to blood relationship, with a closer relationship increasing the risk of congenital heart disease. Genetic factors appear to play an important role in congenital heart disease.

Cellular decisions in cardiac outflow tract and coronary development: an act by VEGF and NOTCH

Congenital cardiac abnormalities are, due to their relatively high frequency and severe impact on quality of life, an important focus in cardiovascular research. Recently, various human studies have revealed a high coincidence of VEGF and NOTCH polymorphisms with cardiovascular outflow tract anomalies, such as bicuspid aortic valves and Tetralogy of Fallot, next to predisposition for cardiovascular pathologies, including atherosclerosis and aortic valve calcification. This genetic association between VEGF/NOTCH mutations and congenital cardiovascular defects in humans has been supported by substantial proof from animal models, revealing interaction of both pathways in cellular processes that are crucial for cardiac development. This review focuses on the role of VEGF and NOTCH signaling and their interplay in cardiogenesis with special interest to coronary and outflow tract development. An overview of the association between congenital malformations and VEGF/NOTCH polymorphisms in humans will be discussed along with their potential mechanisms and processes as revealed by transgenic mouse models. The molecular and cellular interaction of VEGF and subsequent Notch-signaling in these processes will be highlighted.

A nonsense variation p.Arg325X in the vascular endothelial growth factor-A gene may be associated with congenital tricuspid aortic valve stenosis

BACKGROUND

In our recent study, we first reported that mutation in vascular endothelial growth factor-A is associated with bicuspid aortic valve stenosis. However, to date no groups have explored the role of vascular endothelial growth factor-A variations in the aetiology of congenital tricuspid aortic valve stenosis.

METHODS

We sequenced all eight coding exons and exon-intron boundaries of the vascular endothelial growth factor-A gene in deoxyribonucleic acid samples of a cohort of 32 sporadic patients with tricuspid aortic valve stenosis, 300 normal controls, and 103 disease controls - conotruncal defects - in order to identify sequence variants.

RESULTS

We identified a c.973C > T heterozygous nonsense variation in exon 6 of the vascular endothelial growth factor-A gene in a patient with an isolated tricuspid aortic valve stenosis. The c.973C > T variation, which was absent in all controls, changes a highly conserved arginine at amino acid position 325 to a stop codon (p.Arg325X) and is predicted to produce a truncated protein of 324 amino acid residues. The proband's parents had a normal cardiac phenotype; however, his father was a carrier of the p.Arg325X variation, which indicates that the p.Arg325X variation is inherited and incompletely penetrant.

CONCLUSION

We report for the first time that the p.Arg325X nonsense variation in the vascular endothelial growth factor-A gene may be associated with congenital tricuspid aortic valve stenosis.

Percutaneous Balloon Valvuloplasty for Aortic Stenosis in Newborns and Children

In all cases of congenital valvar aortic stenosis (AS), reduced effective orifice area leads to obstruction to flow, usually resulting from thickening and reduced motion of the valve leaflets. The most severe cases of valvar AS present soon after birth, with low cardiac output secondary to left ventricular dysfunction. Interventional treatment options consist of open surgical valvotomy or balloon valvuloplasty, with both therapies providing excellent but usually only temporary relief of stenosis. This article focuses on balloon aortic valvuloplasty as a therapy for congenital valvar AS in infants and children, focusing on established techniques, outcomes, and future challenges.

Chromosome 19p13.3 deletion in a child with Peutz-Jeghers syndrome, congenital heart defect, high myopia, learning difficulties and dysmorphic features: Clinical and molecular characterization of a new contiguous gene syndrome

The Peutz-Jeghers syndrome (PJS) is an autosomal-dominant hamartomatous polyposis syndrome characterized by mucocutaneous pigmentation, gastrointestinal polyps and the increased risk of multiple cancers. The causative point mutation in the STK11 gene of most patients accounts for about 30% of the cases of partial and complete gene deletion. This is a report on a girl with PJS features, learning difficulties, dysmorphic features and cardiac malformation, bearing a de novo 1.1 Mb deletion at 19p13.3. This deletion encompasses at least 47 genes, including STK11. This is the first report on 19p13.3 deletion associated with a PJS phenotype, as well as other atypical manifestations, thereby implying a new contiguous gene syndrome.