Molecular insight into heart development and congenital heart disease: An update review from the Arab countries

Association of MTR gene polymorphisms with the occurrence of non-syndromic congenital heart disease: a case-control study

To exhaustively explore the association of infant genetic polymorphisms of methionine synthase (MTR) gene with the risk of non-syndromic congenital heart disease (CHD). A hospital-based case-control study involving 620 CHD cases and 620 health controls was conducted from November 2017 to March 2020. Eighteen SNPs were detected and analyzed. Our date suggested that the genetic polymorphisms of MTR gene at rs1805087 (GG vs. AA: aOR = 6.85, 95% CI 2.94-15.96; the dominant model: aOR = 1.77, 95% CI 1.35-2.32; the recessive model: aOR = 6.26, 95% CI 2.69-14.54; the addictive model: aOR = 1.81, 95% CI 1.44-2.29) and rs2275565 (GT vs. GG: aOR = 1.52, 95% CI 1.15-1.20; TT vs. GG: aOR = 4.93, 95% CI 1.93-12.58; the dominant model: aOR = 1.66, 95% CI 1.27-2.17; the recessive model: aOR = 4.41, 95% CI 1.73-11.22; the addictive model: aOR = 1.68, 95% CI 1.32-2.13) were significantly associated with the higher risk of CHD. And three haplotypes of G-A-T (involving rs4659724, rs95516 and rs4077829; OR = 5.48, 95% CI 2.58-11.66), G-C-A-T-T-G (involving rs2275565, rs1266164, rs2229276, rs4659743, rs3820571 and rs1050993; OR = 0.78, 95% CI 0.63-0.97) and T-C-A-T-T-G (involving rs2275565, rs1266164, rs2229276, rs4659743, rs3820571 and rs1050993; OR = 1.60, 95% CI 1.26-2.04) were observed to be significantly associated with risk of CHD. Our study found that genetic polymorphisms of MTR gene at rs1805087 and rs2275565 were significantly associated with higher risk of CHD. Additionally, our study revealed a significant association of three haplotypes with risk of CHD. However, the limitations in this study should be carefully taken into account. In the future, more specific studies in different ethnic populations are required to refine and confirm our findings.Trial registration: Registration number: ChiCTR1800016635; Date of first registration: 14/06/2018.

Investigation of Copy Number Variation in South African Patients With Congenital Heart Defects

BACKGROUND

Congenital heart disease (CHD) is a leading non-infectious cause of pediatric morbidity and mortality worldwide. Although the etiology of CHD is poorly understood, genetic factors including copy number variants (CNVs) contribute to the risk of CHD in individuals of European ancestry. The presence of rare CNVs in African CHD populations is unknown. This study aimed to identify pathogenic and likely pathogenic CNVs in South African patients with CHD.

METHODS

Genotyping was performed on 90 patients with nonsyndromic CHD using the Affymetrix CytoScan HD platform. These data were used to identify large, rare CNVs in known CHD-associated genes and candidate genes.

RESULTS

We identified eight CNVs overlapping known CHD-associated genes (GATA4, CRKL, TBX1, FLT4, B3GAT3, NSD1) in six patients. The analysis also revealed CNVs encompassing five candidate genes likely to play a role in the development of CHD (DGCR8, KDM2A, JARID2, FSTL1, CYFIP1) in five patients. One patient was found to have 47, XXY karyotype. We report a total discovery yield of 6.7%, with 5.6% of the cohort carrying pathogenic or likely pathogenic CNVs expected to cause the observed phenotypes.

CONCLUSIONS

In this study, we show that chromosomal microarray is an effective technique for identifying CNVs in African patients diagnosed with CHD and have demonstrated results similar to previous CHD genetic studies in Europeans. Novel potential CHD genes were also identified, indicating the value of genetic studies of CHD in ancestrally diverse populations.

Investigation of Genetic Causes in Patients with Congenital Heart Disease in Qatar: Findings from the Sidra Cardiac Registry

Congenital heart disease (CHD) is one of the most common forms of birth defects worldwide, with a prevalence of 1–2% in newborns. CHD is a multifactorial disease partially caused by genetic defects, including chromosomal abnormalities and single gene mutations. Here, we describe the Sidra Cardiac Registry, which includes 52 families and a total of 178 individuals, and investigate the genetic etiology of CHD in Qatar. We reviewed the results of genetic tests conducted in patients as part of their clinical evaluation, including chromosomal testing. We also performed whole exome sequencing (WES) to identify potential causative variants. Sixteen patients with CHD had chromosomal abnormalities that explained their complex CHD phenotype, including six patients with trisomy 21. Moreover, using exome analysis, we identified potential CHD variants in 24 patients, revealing 65 potential variants in 56 genes. Four variants were classified as pathogenic/likely pathogenic based on the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) classification; these variants were detected in four patients. This study sheds light on several potential genetic variants contributing to the development of CHD. Additional functional studies are needed to better understand the role of the identified variants in the pathogenesis of CHD.

Fetal Congenital Heart Disease Caused by Compound Heterozygous Mutations in the DNAH9 Gene: A Case Report

Background: Fetal congenital heart disease (CHD) is the most common congenital defect, with an incidence of 0.6–0.8%, accounting for 30–50% of infant congenital disease deaths. The pathogenesis of CHD is still unclear, so an active and effective prenatal diagnosis is very important for the prevention and control of CHD. Herein, a Chinese CHD patient with rare compound heterozygous mutations in the DNAH9 gene was reported, and the 3D structure and functional changes of DNAH9 protein were predicted.

Case presentation: A 23-year-old pregnant woman came to our hospital for prenatal diagnosis at 27 weeks of gestation. Both she and her partner were unaffected. Fetal CHD was detected by ultrasound screening. Copy number variation sequencing (CNV-seq) revealed an 81 kb deletion at chr17p12 (11,486,795–11,568,385), including exons 1–15 of DNAH9 gene, which plays a key role in cardiac development. Then, whole exome sequencing (WES) was used and identified a nonsense mutation (c.10975C>T) in DNAH9, which resulted in the mutation of amino acid 3,659 from glutamine to termination. The 3D mutant protein structures were predicted using SWISS-MODEL and showed structural changes from functional β-sheet and α-helix to termination, respectively.

Conclusion: We describe a case of fetal CHD caused by DNAH9 mutations and provide an effective diagnostic technique for identifying intragenic deletions. This diagnostic process can be implicated in prenatal diagnosis of CHD.

Genetic evaluation of cardiomyopathies in Qatar identifies enrichment of pathogenic sarcomere gene variants and possible founder disease mutations in the Arabs

Background

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are serious inherited heart diseases with various causative mutations identified. The full spectrum of causative mutations remains to be discovered, especially in understudied populations.

Methods

Here, we established the DOHA Registry and Biobank for cardiomyopathies in Qatar, followed by sequencing of 174 genes on 51 HCM and 53 DCM patients, and 31 relatives.

Results

In HCM, the analysis of 25 HCM‐associated genes showed that 20% of HCM cases had putative pathogenic variants for cardiomyopathy, mainly in sarcomere genes. Additional 49% of HCM cases had variants of uncertain significance, while 31% of HCM cases had likely benign variant(s) or had no variants identified within the analyzed HCM genes. In DCM, 56 putative DCM genes were analyzed. Eight percent of DCM cases had putative pathogenic variants for DCM, in the TTN gene while 70% of cases had variants of uncertain significance, in the analyzed DCM genes, that will need further pathogenicity assessment. Moreover, 22% of DCM cases remain unexplained, by having likely benign variant(s) or having no variants detected in any of the analyzed DCM genes.

Conclusion

We identified or replicated at least four recurrent variants among cardiomyopathy patients, which could be founder disease mutations in the Arabic population, including a frameshift variant (c.1371_1381dupTATCCAGTTAT) of unknown significance in the FKTN gene which seems to cause DCM in homozygosity, and HCM in heterozygosity. In vivo and/or in vitro functional validation need to be pursued in order to assess the pathogenicity of the identified variants.

Absence of GATA4 Mutations in Moroccan Patients with Atrial Septal Defect (ASD) Provides Further Evidence of Limited Involvement of GATA4 in Major Congenital Heart Defects

Objective

Atrial septal defect (ASD) is one of the most common types of congenital heart disease (CHD). It is mainly caused by mutations of NK2 homeobox 5, GATA binding protein 4 (GATA4), and myosin heavy chain 6 in non-syndromic cases. This study aims to carry out, for the first time, the GATA4 mutation screening in a Moroccan population affected by ASD and compare the obtained mutation rate across populations.

Materials and Methods

A total of 33 patients were enrolled in this study. DNAs were extracted from peripheral blood samples, and we performed PCR-sequencing for GATA4 coding regions. Sequences were analyzed by sequence alignment and functional impact prediction tools. Mutation rate comparisons were performed by R software using the appropriate statistical tests.

Results

We detected 7 variants, but no pathogenic mutation was revealed, except for Asn352= that was assessed by human splicing finder algorithms to have a potential impairing effect on the splicing mechanism. Until proven by in vitro functional studies, the current pathogenic mutation rate in our cohort seems to be 0%. Statistical comparison with previous studies from all over the world shows no significant difference. Seemingly, comparison of previous GATA4 mutation rates among tetralogy of Fallot (TOF) populations shows no significant difference.

Conclusion

The low rates of GATA4 mutations observed throughout ASD and TOF international populations may suggest a limited causality of GATA4 mutations in the main CHDs, which further confirms the co-involvement of additional genetic and/or environmental factors in the manifestation of these phenotypes.

Associations between IL-6 Variations and Congenital Heart Disease Incidence among Chinese Han People

Background

Our research explored if Interleukin-6 (IL-6) variants held substantial connection to congenital heart disease (CHD) susceptibility among Chinese Han children.

Material/Methods

A total of 102 CHD children were recruited as the case group while 98 healthy persons were recruited as the control group. We used polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) completed genotyping for IL-6 variants rs1800795 and rs1800796. The Hardy-Weinberg equilibrium (HWE) among controls was tested using χ² analysis. Genotype and allele frequencies for variants were compared between groups. Odds ratio (OR) accompanied by 95% confidence interval (CI) reflected the potential link of IL-6 variants to CHD occurrence.

Results

A remarkable increased trend of rs1800795 CC genotype and C allele was detected in the CHD patient group (P<0.05). Individuals carrying rs1800795 CC genotype showed higher risk for CHD (OR=3.763, 95% CI=1.162–12.190). In addition, rs1800795 C allele could increase CHD incidence (OR=1.766, 95% CI=1.101–2.832). No significant differences were detected in IL-6 gene rs1800796 polymorphism in both genotype and allele distributions between the case group and the control group (P>0.05). These associations had no significant alteration after the adjustment of age, gender, maternal smoking history, and maternal history of diabetes.

Conclusions

IL-6 variant rs1800795 exhibited a close relation to CHD susceptibility among Chinese Han people while the mutant C allele promoted CHD incidence. But rs1800796 variant showed no such influence.

The 22q11.2 Microdeletion in Pediatric Patients with Cleft Lip, Palate, or Both and Congenital Heart Disease: A Systematic Review

The 22q11.2 deletion syndrome (22q11.2DS) is present in approximately 5 to 8% of patients with cleft lip, palate, or both (CL/P) and 75 to 80% of patients with congenital heart disease (CHD). In a literature review, we consider this association of 22q11.2DS in pediatric patients with CL/P and CHD. Early diagnosis of 22q11.2DS in pediatric patients with CL/P and CHD helps to optimize a multidisciplinary treatment approach for 22q11DS. Early diagnosis, thereby, can improve quality of life for these patients and awareness of other potential clinical implications that may require attention throughout the patient's life.

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.

A Novel Missense Mutation of GATA4 in a Chinese Family with Congenital Heart Disease

Background

Congenital heart disease (CHD) is the most prevalent type of birth defect in human, with high morbidity in infant. Several genes essential for heart development have been identified. GATA4 is a pivotal transcription factor that can regulate the cardiac development. Many GATA4 mutations have been identified in patients with different types of CHD.

Aims

In this study, the NKX2-5, HAND1 and GATA4 coding regions were sequenced in a family spanning three generations in which seven patients had CHD. Disease-causing potential variation in this family was evaluated by bioinformatics programs and the transcriptional activity of mutant protein was analyzed by the dual luciferase reporter assay.

Results

A novel GATA4 mutation, c.C931T (p.R311W), was identified and co-segregated with the affected patients in this family. The bioinformatics programs predicted this heterozygous mutation to be deleterious and the cross-species alignment of GATA4 sequences showed that the mutation occurred within a highly conserved amino acid. Even though it resided in the nuclear localization signal domain, the mutant protein didn’t alter its intracellular distribution. Nevertheless, further luciferase reporter assay demonstrated that the p.R311W mutation reduced the ability of GATA4 to activate its downstream target gene.

Conclusions

Our study identified a novel mutation in GATA4 that likely contributed to the CHD in this family. This finding expanded the spectrum of GATA4 mutations and underscored the pathogenic correlation between GATA4 mutations and CHD.

Functions of miRNAs during Mammalian Heart Development

MicroRNAs (miRNAs) play essential roles during mammalian heart development and have emerged as attractive therapeutic targets for cardiovascular diseases. The mammalian embryonic heart is mainly derived from four major cell types during development. These include cardiomyocytes, endocardial cells, epicardial cells, and neural crest cells. Recent data have identified various miRNAs as critical regulators of the proper differentiation, proliferation, and survival of these cell types. In this review, we briefly introduce the contemporary understanding of mammalian cardiac development. We also focus on recent developments in the field of cardiac miRNAs and their functions during the development of different cell types.

Genetic testing in congenital heart disease: A clinical approach

Congenital heart disease (CHD) is the most common type of birth defect. Traditionally, a polygenic model defined by the interaction of multiple genes and environmental factors was hypothesized to account for different forms of CHD. It is now understood that the contribution of genetics to CHD extends beyond a single unified paradigm. For example, monogenic models and chromosomal abnormalities have been associated with various syndromic and non-syndromic forms of CHD. In such instances, genetic investigation and testing may potentially play an important role in clinical care. A family tree with a detailed phenotypic description serves as the initial screening tool to identify potentially inherited defects and to guide further genetic investigation. The selection of a genetic test is contingent upon the particular diagnostic hypothesis generated by clinical examination. Genetic investigation in CHD may carry the potential to improve prognosis by yielding valuable information with regards to personalized medical care, confidence in the clinical diagnosis, and/or targeted patient follow-up. Moreover, genetic assessment may serve as a tool to predict recurrence risk, define the pattern of inheritance within a family, and evaluate the need for further family screening. In some circumstances, prenatal or preimplantation genetic screening could identify fetuses or embryos at high risk for CHD. Although genetics may appear to constitute a highly specialized sector of cardiology, basic knowledge regarding inheritance patterns, recurrence risks, and available screening and diagnostic tools, including their strengths and limitations, could assist the treating physician in providing sound counsel.

Association Between DSCR1 Variations and Congenital Heart Disease Susceptibility

Background

The objective of this study was aimed to detect the association of Down syndrome critical region 1 (DSCR1) gene polymorphisms (rs149048873 and rs143081213) and congenital heart disease (CHD) susceptibility.

Material/Methods

This case-control study included 102 CHD patients and 113 healthy controls. Cases and controls were matched in age and gender. Genotypes of DSCR1 gene polymorphisms were detected by TaqMan method in cases and controls. Hardy-Weinberg equilibrium (HWE) examination was performed by PLINK 1.0 software. Chi square test was utilized to assess the distribution of the genotypes and the alleles. Relative risk of CHD was presented by odds ratios (ORs) with 95% confidence intervals (CIs). All of the calculations were implemented using SPSS 18.0.

Results

Variant genotype distribution of rs149048873 and rs143081213 mutations were higher in cases than in controls, but the differences were not statistically obvious (P>0.05). Additionally, frequencies of mutant allele of the two polymorphisms were also significantly different in case and control groups (P>0.05).

Conclusions

No significant associations existed between DSCR1 gene rs149048873 and rs143081213 polymorphisms and CHD susceptibility.