New Genetic Insights into Congenital Heart Disease

A Novel Missense Heterozygous Mutation in NKX2-5 Gene in a Family with Congenital Septal Defects and Cardiomyopathy: Case Series and Literature Review

Single-gene mutations are important causes of congenital heart defects in children. Mutations in the NKX2-5 gene have been recently described in the literature as a cause of septal defects and cardiomyopathy. However, the spectrum of cardiac disease associated with NKX2-5 gene mutations is variable, ranging from asymptomatic septal defects to cardiomyopathy and sudden death. In this case report, we describe a case of 2-year-old child, along with two other family members, with a novel missense heterozygous (c.544G > T p.[Val182Phe]) mutation in NKX2-5 gene consistent with the diagnosis of autosomal dominant atrial septal defects with cardiomyopathy. This report can contribute to the understanding of genotype-phenotype correlations; it emphasizes the significant clinical relevance of NKX2-5 gene defects for congenital heart defects, sudden death, and cardiomyopathy, especially in multiple affected family members. It also suggests that individuals with NKX2-5 mutations are at risk of lethal arrhythmias and conduction disorders, that is why they should be evaluated routinely to assess the need for implantable cardioverter-defibrillator or pacemaker implantation.

Massive Parallel DNA Sequencing of Patients with Inherited Cardiomyopathies in Cyprus and Suggestion of Digenic or Oligogenic Inheritance

Inherited cardiomyopathies represent a highly heterogeneous group of cardiac diseases. DNA variants in genes expressed in cardiomyocytes cause a diverse spectrum of cardiomyopathies, ultimately leading to heart failure, arrythmias, and sudden cardiac death. We applied massive parallel DNA sequencing using a 72-gene panel for studying inherited cardiomyopathies. We report on variants in 25 families, where pathogenicity was predicted by different computational approaches, databases, and an in-house filtering analysis. All variants were validated using Sanger sequencing. Familial segregation was tested when possible. We identified 41 different variants in 26 genes. Analytically, we identified fifteen variants previously reported in the Human Gene Mutation Database: twelve mentioned as disease-causing mutations (DM) and three as probable disease-causing mutations (DM?). Additionally, we identified 26 novel variants. We classified the forty-one variants as follows: twenty-eight (68.3%) as variants of uncertain significance, eight (19.5%) as likely pathogenic, and five (12.2%) as pathogenic. We genetically characterized families with a cardiac phenotype. The genetic heterogeneity and the multiplicity of candidate variants are making a definite molecular diagnosis challenging, especially when there is a suspicion of incomplete penetrance or digenic-oligogenic inheritance. This is the first systematic study of inherited cardiac conditions in Cyprus, enabling us to develop a genetic baseline and precision cardiology.

Molecular Pathways and Animal Models of Defects in Situs

Left-right patterning is among the least well understood of the three axes defining the body plan, and yet it is no less important, with left-right patterning defects causing structural birth defects with high morbidity and mortality, such as complex congenital heart disease, biliary atresia, or intestinal malrotation. The cell signaling pathways governing left-right asymmetry are highly conserved and involve multiple components of the TGF-β superfamily of cell signaling molecules. Central to left-right patterning is the differential activation of Nodal on the left, and BMP signaling on the right. In addition, a plethora of other cell signaling pathways including Shh, FGF, and Notch also contribute to the regulation of left-right patterning. In vertebrate embryos such as the mouse, frog, or zebrafish, the specification of left-right identity requires the left-right organizer (LRO) containing cells with motile and primary cilia that mediate the left-sided propagation of Nodal signaling, followed by left-sided activation of Lefty and then Pitx2, a transcription factor that specifies visceral organ asymmetry. While this overall scheme is well conserved, there are striking species differences, including the finding that motile cilia do not play a role in left-right patterning in some vertebrates. Surprisingly, the direction of heart looping, one of the first signs of organ left-right asymmetry, was recently shown to be specified by intrinsic cell chirality, not Nodal signaling, possibly a reflection of the early origin of Nodal signaling in radially symmetric organisms. How this intrinsic chirality interacts with downstream molecular pathways regulating visceral organ asymmetry will need to be further investigated to elucidate how disturbance in left-right patterning may contribute to complex CHD.

Exploring Genetic Diversity of SOD2 and POU5F1 for Congenital Heart Disease in the Southwest Chinese Population

Congenital heart disease (CHD) accounts for nearly one-third of all major congenital anomalies, with atrial septal defect (ASD) and ventricular septal defect (VSD) being the most common forms of simple CHD, which involve a large number of susceptibility genes. However, despite extensive research, the etiology of ASD and VSD remains unclear. Yunnan Province has advantages in exploring CHD pathogenesis due to its unique genetic background. Therefore, we aimed to evaluate the association between single nucleotide polymorphisms (SNPs) of genes and susceptibility to simple CHD in a specific population by means of a case-control study. A total of 337 healthy controls and 767 patients with simple CHD (501 ASD and 266 VSD) from China were recruited. Candidate SNPs were identified through whole-genome sequencing of pooled CHD patients and controls (pool-seq). Genotyping from 1,104 samples was performed, and stratified analysis was conducted to explore the association between positive SNPs and CHD subtypes. χ2 tests and logistic regression were used to analyze the relationship between each SNP and simple CHD. Of 11 SNPs identified, SOD2 rs62437333 (P = 0.005) and POU5F1 rs3130504 (P = 0.017) showed differences between the control and ASD cohorts. In the dominant inheritance model hypothesis, rs62437333 allele C carriers had increased ASD (odds ratio (OR) = 2.04, P = 0.005) and combined simple CHD risk (OR = 2.33, P = 0.012) compared to DD genotype, while rs3130504 allele C carriers had increased ASD risk (OR = 1.121, P = 0.045) compared to DD genotype.

Integrated genomic analysis identifies novel low-frequency cis-regulatory variant rs2279658 associated with VSD risk in Chinese children

VSD combined with other cardiac or extracardiac malformations (defined as "complex VSD" by us) is one of the major causes of perinatal morbidity and mortality. Functional non-coding SNPs (cis-regulatory SNPs) have not been systematically studied in CHDs, including complex VSD. Here we report an exome-wide association analysis using WES data of 60 PA/VSD cases, 20 TOF cases and 100 controls in Chinese children. We identify 93 low-frequency non-coding SNPs associated with complex VSD risk. A functional genomics pipeline integrating ATAC-seq, ChIP-seq and promoter CHi-C recognizes the rs2279658 variant as a candidate cis-regulatory SNP. Specifically, rs2279658 resides in a cardiac-specific enhancer bound by FOXH1 and PITX2, and would abrogate binding of these two transcription factors to the identified enhancer during cardiac morphogenesis. COQ2 and FAM175A are predicted to be target genes for "rs2279658-FOXH1 or PITX2" pairs in the heart. These findings highlight the importance of cis-regulatory SNPs in the pathogenesis of complex VSD and broaden our understanding of this disease.

Novel MYO1D Missense Variant Identified Through Whole Exome Sequencing and Computational Biology Analysis Expands the Spectrum of Causal Genes of Laterality Defects

Laterality defects (LDs) or asymmetrically positioned organs are a group of rare developmental disorders caused by environmental and/or genetic factors. However, the exact molecular pathophysiology of LD is not yet fully characterised. In this context, studying Arab population presents an ideal opportunity to discover the novel molecular basis of diseases owing to the high rate of consanguinity and genetic disorders. Therefore, in the present study, we studied the molecular basis of LD in Arab patients, using next-generation sequencing method. We discovered an extremely rare novel missense variant in MYO1D gene (Pro765Ser) presenting with visceral heterotaxy and left isomerism with polysplenia syndrome. The proband in this index family has inherited this homozygous variant from her heterozygous parents following the autosomal recessive pattern. This is the first report to show MYO1D genetic variant causing left-right axis defects in humans, besides previous known evidence from zebrafish, frog and Drosophila models. Moreover, our multilevel bioinformatics-based structural (protein variant structural modelling, divergence, and stability) analysis has suggested that Ser765 causes minor structural drifts and stability changes, potentially affecting the biophysical and functional properties of MYO1D protein like calmodulin binding and microfilament motor activities. Functional bioinformatics analysis has shown that MYO1D is ubiquitously expressed across several human tissues and is reported to induce severe phenotypes in knockout mouse models. In conclusion, our findings show the expanded genetic spectrum of LD, which could potentially pave way for the novel drug target identification and development of personalised medicine for high-risk families.

De Novo KMT2D Heterozygous Frameshift Deletion in a Newborn with a Congenital Heart Anomaly

Kabuki syndrome (KS) is characterized by typical facial features and patients are also affected by multiple congenital anomalies, of which congenital heart anomalies (CHAs) are present in 28.0 to 80.0%. In approximately 75.0% of patients, the genetic causes of KS are caused by mutation in the KMT2D gene. Although KS is a well-characterized syndrome, reaching the diagnosis in neonates is still challenging. Namely, newborns usually display mild facial features; therefore the diagnosis is mainly based on congenital malformations. In our case, a newborn was referred for next generation sequencing (NGS) testing due to the prenatally observed CHA. After birth, a ventricular septal defect (VSD), vesicoureteral reflux, muscular hypotonia, cleft palate, mild microcephaly, and some dysmorphic features, were noted. The NGS analysis was performed on the proband’s genomic DNA using the TruSight One Sequencing Panel, which enriches exons of 4813 genes with clinical relevance to the disease. After variant calling, NGS data analysis was predominantly focused on rare variants in genes involved in VSD, microcephaly, and muscular hypotonia; features observed predominantly in our proband. With the aforementioned protocol, we were able to determine the previously unreported de novo frameshift deletion in the KMT2D gene resulting in translation termination. Although our proband is a typical representative of KS, his diagnosis was reached only after NGS analysis. Our proband thus represents the importance of genotypephenotype driven NGS analysis in diagnosis of patients with congenital anomalies.

Histone deacetylases in modulating cardiac disease and their clinical translational and therapeutic implications

Cardiovascular diseases are the leading cause of mortality and morbidity worldwide. Histone deacetylases (HDACs) play an important role in the epigenetic regulation of genetic transcription in response to stress or pathological conditions. HDACs interact with a complex co-regulatory network of transcriptional regulators, deacetylate histones or non-histone proteins, and modulate gene expression in the heart. The selective HDAC inhibitors have been considered to be a critical target for the treatment of cardiac disease, especially for ameliorating cardiac dysfunction. In this review, we discuss our current knowledge of the cellular and molecular basis of HDACs in mediating cardiac development and hypertrophy and related pharmacologic interventions in heart disease.

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.

Copy number variations in the GATA4, NKX2-5, TBX5, BMP4 CRELD1, and 22q11.2 gene regions in Chinese children with sporadic congenital heart disease

BACKGROUND

Congenital heart disease (CHD) is a common birth defect originating from both environmental and genetic factors. An overabundance of copy number variations (CNVs) affecting cardiac-related genes has previously been detected in individuals with CHD.

OBJECTIVE

To evaluate if the presence of CNVs in the 22q11.2 region, and to determine whether GATA4, NKX2-5, TBX5, BMP, and CRELD1 genes contributed toward the pathogenesis of isolated incidences of CHDs in southwest China.

METHODS

In total 167 patients from southwest China with sporadic CHD were studied, including 121 patients with ventricular septal defect (VSD), 24 with atrial septal defect (ASD), 12 with tetralogy of fallot (TOF), six VSD cases with TOF, two cases with patent ductus arteriosus (PDA), and two VSD cases with ASD. 22q11.2, GATA4, NKX2-5, TBX5, BMP4, and CRELD1 regions were screened using MLPA and copy number variation sequencing (CNV-Seq).

RESULTS

A 2.5-2.8 Mb deletion in the 22q11.2 region was identified in 5 patients with CHD. Two of these patients were diagnosed with VSD, while two had VSD and ASD, and the other had TOF. 5 patients correspond to the same classical DiGeorge syndrome. A 0.86 Mb duplication in the 22q11.2 region was identified in a PDA patient, whom was without extracardiac symptoms.

CONCLUSION

These data suggest that copy number variation in the 22q11.2 region is common in CHD patients in southwest China. Regardless of the presence or absence of extracardiac symptoms, results also indicate that it is necessary to perform prenatal screening for CHD.

Genetic architecture of laterality defects revealed by whole exome sequencing

Aberrant left-right patterning in the developing human embryo can lead to a broad spectrum of congenital malformations. The causes of most laterality defects are not known, with variants in established genes accounting for <20% of cases. We sought to characterize the genetic spectrum of these conditions by performing whole-exome sequencing of 323 unrelated laterality cases. We investigated the role of rare, predicted-damaging variation in 1726 putative laterality candidate genes derived from model organisms, pathway analyses, and human phenotypes. We also evaluated the contribution of homo/hemizygous exon deletions and gene-based burden of rare variation. A total of 28 candidate variants (26 rare predicted-damaging variants and 2 hemizygous deletions) were identified, including variants in genes known to cause heterotaxy and primary ciliary dyskinesia (ACVR2B, NODAL, ZIC3, DNAI1, DNAH5, HYDIN, MMP21), and genes without a human phenotype association, but with prior evidence for a role in embryonic laterality or cardiac development. Sanger validation of the latter variants in probands and their parents revealed no de novo variants, but apparent transmitted heterozygous (ROCK2, ISL1, SMAD2), and hemizygous (RAI2, RIPPLY1) variant patterns. Collectively, these variants account for 7.1% of our study subjects. We also observe evidence for an excess burden of rare, predicted loss-of-function variation in PXDNL and BMS1- two genes relevant to the broader laterality phenotype. These findings highlight potential new genes in the development of laterality defects, and suggest extensive locus heterogeneity and complex genetic models in this class of birth defects.

Congenital anomalies of the pulmonary arteries: an imaging overview

Congenital pulmonary artery anomalies represent a diverse group of abnormalities, ranging from asymptomatic incidental findings to causes of sudden cardiac death. While some may be recognized in childhood, others may be found incidentally in adulthood. We review the clinical and imaging findings in patients with congenital anomalies of the pulmonary arteries, including valvular and perivavular anomalies as well as abnormal narrowing, course and communications of the pulmonary arteries. We also discuss the role of various imaging modalities in the evaluation of these patients. It is vital to be aware of the key radiologic manifestations and associated haemodynamic consequences in these conditions in order to facilitate accurate diagnosis and prognostic stratification.

The Role of scaRNAs in Adjusting Alternative mRNA Splicing in Heart Development

Congenital heart disease (CHD) is a leading cause of death in children <1 year of age. Despite intense effort in the last 10 years, most CHDs (~70%) still have an unknown etiology. Conotruncal based defects, such as Tetralogy of Fallot (TOF), a common complex of devastating heart defects, typically requires surgical intervention in the first year of life. We reported that the noncoding transcriptome in myocardial tissue from children with TOF is characterized by significant variation in levels of expression of noncoding RNAs, and more specifically, a significant reduction in 12 small cajal body-associated RNAs (scaRNAs) in the right ventricle. scaRNAs are essential for the biochemical modification and maturation of small nuclear RNAs (spliceosomal RNAs), which in turn are critical components of the spliceosome. This is particularly important because we also documented that splicing of mRNAs that are critical for heart development was dysregulated in the heart tissue of infants with TOF. Furthermore, we went on to show, using the zebrafish model, that altering the expression of these same scaRNAs led to faulty mRNA processing and heart defects in the developing embryo. This review will examine how scaRNAs may influence spliceosome fidelity in exon retention during heart development and thus contribute to regulation of heart development.

Williams Syndrome and Right Ventricular Noncompaction: A Rare Association

Ventricular noncompaction and Williams syndrome are genetic disorders with typical clinical and echocardiographic cardiovascular manifestations. Here, we describe a young patient with rare association of clinical phenotype suggestive of Williams syndrome and right ventricular noncompaction.

Identification of Novel Congenital Heart Disease Candidate Genes Using Chromosome Microarray

While the majority of patients have isolated heart disease, congenital heart disease (CHD) may be associated with other congenital anomalies or syndromes. Our institution utilizes chromosomal microarray (CMA) to identify chromosomal abnormalities, specifically copy number variations (CNVs). While CNVs have been associated with CHD, their direct impact on cardiac development remains unclear. This study sought to identify potential novel CHD candidate genes by comparing CNVs present in our institution's CHD population with those already recognized in the literature. A list of candidate genes was compiled from recent medical literature that utilized CMA. Records from neonatal cases at our institution over 10 years were reviewed. Genes identified from CMAs were compared with those reported in the literature and cross-referenced with the Online Mendelian Inheritance in Man catalog. We identified 375 CNVs reported in patients with CHD. At our institution between 2005 and 2015, 307 neonates with CHD had CMA. Of these, 77 patients (25%) had CNVs containing 832 unique candidate genes. 49 patients (16%) had isolated CHD with 353 candidate genes expressed within the CNVs, many of which were previously reported. However, there were 16 unique candidate genes identified that have been expressed with heart structure of the mouse knock-out models. Our findings demonstrate a high incidence of abnormal genes identified by CMA in CHD patients, including many CNVs of "unknown clinical significance". We conclude that a portion of these CNVs (including 16 genes expressed in the heart of the mouse knock-out models) could be candidate genes involved in CHD pathogenesis.

Whole exome sequencing in 342 congenital cardiac left sided lesion cases reveals extensive genetic heterogeneity and complex inheritance patterns

BACKGROUND

Left-sided lesions (LSLs) account for an important fraction of severe congenital cardiovascular malformations (CVMs). The genetic contributions to LSLs are complex, and the mutations that cause these malformations span several diverse biological signaling pathways: TGFB, NOTCH, SHH, and more. Here, we use whole exome sequence data generated in 342 LSL cases to identify likely damaging variants in putative candidate CVM genes.

METHODS

Using a series of bioinformatics filters, we focused on genes harboring population-rare, putative loss-of-function (LOF), and predicted damaging variants in 1760 CVM candidate genes constructed a priori from the literature and model organism databases. Gene variants that were not observed in a comparably sequenced control dataset of 5492 samples without severe CVM were then subjected to targeted validation in cases and parents. Whole exome sequencing data from 4593 individuals referred for clinical sequencing were used to bolster evidence for the role of candidate genes in CVMs and LSLs.

RESULTS

Our analyses revealed 28 candidate variants in 27 genes, including 17 genes not previously associated with a human CVM disorder, and revealed diverse patterns of inheritance among LOF carriers, including 9 confirmed de novo variants in both novel and newly described human CVM candidate genes (ACVR1, JARID2, NR2F2, PLRG1, SMURF1) as well as established syndromic CVM genes (KMT2D, NF1, TBX20, ZEB2). We also identified two genes (DNAH5, OFD1) with evidence of recessive and hemizygous inheritance patterns, respectively. Within our clinical cohort, we also observed heterozygous LOF variants in JARID2 and SMAD1 in individuals with cardiac phenotypes, and collectively, carriers of LOF variants in our candidate genes had a four times higher odds of having CVM (odds ratio = 4.0, 95% confidence interval 2.5-6.5).

CONCLUSIONS

Our analytical strategy highlights the utility of bioinformatic resources, including human disease records and model organism phenotyping, in novel gene discovery for rare human disease. The results underscore the extensive genetic heterogeneity underlying non-syndromic LSLs, and posit potential novel candidate genes and complex modes of inheritance in this important group of birth defects.

Major Contribution of Genomic Copy Number Variation in Syndromic Congenital Heart Disease: The Use of MLPA as the First Genetic Test

Congenital heart disease (CHD) is the most common congenital disorder among live births. When associated with extracardiac abnormalities, it is characterized as a syndromic heart disease (syndromic CHD) and corresponds to 25% of all liveborn infants with a heart defect. The etiology in about 65% of the cases still remains unknown, and in about 35% of the patients, it is associated with genetic factors. In the present study, MLPA and SNP-array techniques were used to investigate a group of 47 patients with syndromic CHD. In total, 16 defects (34%) were identified, of which 12 (25.5%) were classified as pathogenic or probably pathogenic. The most frequent abnormalities were 22q11.2 deletion (22q11.2 deletion syndrome) and 7q11.23 deletion (Williams-Beuren syndrome). We also show that rarer malformations may be associated with syndromic CHD, such as 14q32.33 deletion as well as 17q25.3, 15q11.2 (BP1-BP2), 22q13.31, and 12p13.31 (SLC2A3) duplications. The present study demonstrates that CNVs are important causal factors and should be studied in patients with syndromic CHD. Furthermore, the use of MLPA as a first screening test was appropriate, as this less expensive technology detected 11 of the 12 pathogenic abnormalities (91.6%).

Conditional Creation and Rescue of Nipbl-Deficiency in Mice Reveals Multiple Determinants of Risk for Congenital Heart Defects

Elucidating the causes of congenital heart defects is made difficult by the complex morphogenesis of the mammalian heart, which takes place early in development, involves contributions from multiple germ layers, and is controlled by many genes. Here, we use a conditional/invertible genetic strategy to identify the cell lineage(s) responsible for the development of heart defects in a Nipbl-deficient mouse model of Cornelia de Lange Syndrome, in which global yet subtle transcriptional dysregulation leads to development of atrial septal defects (ASDs) at high frequency. Using an approach that allows for recombinase-mediated creation or rescue of Nipbl deficiency in different lineages, we uncover complex interactions between the cardiac mesoderm, endoderm, and the rest of the embryo, whereby the risk conferred by genetic abnormality in any one lineage is modified, in a surprisingly non-additive way, by the status of others. We argue that these results are best understood in the context of a model in which the risk of heart defects is associated with the adequacy of early progenitor cell populations relative to the sizes of the structures they must eventually form.

Association analysis identifies new risk loci for congenital heart disease in Chinese populations

Our previous genome-wide association study (GWAS) identified two susceptibility loci for congenital heart disease (CHD) in Han Chinese. Here we identify additional loci by testing promising associations in an extended 3-stage validation consisting of 6,053 CHD cases and 7,410 controls. We find GW significant (P<5.0 × 10(-8)) evidence of 4 additional CHD susceptibility loci at 4q31.22 (rs1400558, upstream of EDNRA, Pall=1.63 × 10(-9)), 9p24.2 (rs7863990, close to SMARCA2, Pall=3.71 × 10(-14)), 12q24.13 (rs2433752, upstream of TBX3 and TBX5, Pall=1.04 × 10(-10)) and 20q12 (rs490514, in PTPRT, Pall=1.20 × 10(-13)). Moreover, the data from previous European GWAS supports that rs490514 is associated with the risk of CHD (P=3.40 × 10(-3)). These results enhance our understanding of CHD susceptibility.

A novel variant in TBX20 (p.D176N) identified by whole-exome sequencing in combination with a congenital heart disease related gene filter is associated with familial atrial septal defect

Congenital heart disease (CHD) is the leading cause of birth defects, and its etiology is not completely understood. Atrial septal defect (ASD) is one of the most common defects of CHD. Previous studies have demonstrated that mutations in the transcription factor T-box 20 (TBX20) contribute to congenital ASD. Whole-exome sequencing in combination with a CHD-related gene filter was used to detect a family of three generations with ASD. A novel TBX20 mutation, c.526G>A (p.D176N), was identified and co-segregated in all affected members in this family. This mutation was predicted to be deleterious by bioinformatics programs (SIFT, Polyphen2, and MutationTaster). This mutation was also not presented in the current Single Nucleotide Polymorphism Database (dbSNP) or National Heart, Lung, and Blood Institute (NHLBI) Exome Sequencing Project (ESP). In conclusion, our finding expands the spectrum of TBX20 mutations and provides additional support that TBX20 plays important roles in cardiac development. Our study also provided a new and cost-effective analysis strategy for the genetic study in small CHD pedigree.

FISH for 22q11.2 deletion not cost-effective for infants with congenital heart disease with microarray

The objective of this study is to evaluate the yield of genetic testing in infants with congenital heart disease, who undergo surgical intervention prior to one year of age, and develop a cost-effective strategy to screen infants with congenital heart disease for genetic conditions while providing standard of care. 409 charts of patients with congenital heart disease, who underwent surgical intervention prior to one year of age, were retrospectively reviewed for cytogenetic testing results. 278 patients underwent cytogenetic testing, and 89.6 % of these patients had more than one cytogenetic test completed. The most commonly encountered chromosomal anomaly within the sample was Down Syndrome (12.5 %), followed by 22q11.2 Deletion Syndrome (4.6 %). G-Banded Karyotypes were abnormal in 10.5 % of patients, fluorescence in situ hybridization (FISH) probe for 22q11.2 deletion was abnormal in 7.1 % of patients. SNP microarray testing showed the highest yield and was abnormal in 33 % of patients. Based on the data at our institution, a more directed approach of genetic screening with only microarray would have saved our institution approximately $101, 200 on the 103 patients who underwent genetic evaluation with microarray reviewed. Screening infants with congenital heart disease for 22q11.2 deletion with FISH resulted in a loss of approximately $32,000 per 100 patients at our institution. Institutions should develop microarray-based protocols for genetic screening in patients with congenital heart disease with the anticipation of adding lesion-specific single gene testing as single gene testing becomes routinely available.

Investigation of copy number variation in children with conotruncal heart defects

BACKGROUND

Congenital heart defects (CHD) are the most prevalent group of structural abnormalities at birth and one of the main causes of infant morbidity and mortality. Studies have shown a contribution of the copy number variation in the genesis of cardiac malformations.

OBJECTIVES

Investigate gene copy number variation (CNV) in children with conotruncal heart defect.

METHODS

Multiplex ligation-dependent probe amplification (MLPA) was performed in 39 patients with conotruncal heart defect. Clinical and laboratory assessments were conducted in all patients. The parents of the probands who presented abnormal findings were also investigated.

RESULTS

Gene copy number variation was detected in 7/39 patients: 22q11.2 deletion, 22q11.2 duplication, 15q11.2 duplication, 20p12.2 duplication, 19p deletion, 15q and 8p23.2 duplication with 10p12.31 duplication. The clinical characteristics were consistent with those reported in the literature associated with the encountered microdeletion/microduplication. None of these changes was inherited from the parents.

CONCLUSIONS

Our results demonstrate that the technique of MLPA is useful in the investigation of microdeletions and microduplications in conotruncal congenital heart defects. Early diagnosis of the copy number variation in patients with congenital heart defect assists in the prevention of morbidity and decreased mortality in these patients.

Replication of the 4p16 susceptibility locus in congenital heart disease in Han Chinese populations

Congenital heart disease (CHD) is the most common form of congenital human birth anomalies and a leading cause of perinatal and infant mortality. Some studies including our published genome-wide association study (GWAS) of CHD have indicated that genetic variants may contribute to the risk of CHD. Recently, Cordell et al. published a GWAS of multiple CHD phenotypes in European Caucasians and identified 3 susceptibility loci (rs870142, rs16835979 and rs6824295) for ostium secundum atrial septal defect (ASD) at chromosome 4p16. However, whether these loci at 4p16 confer the predisposition to CHD in Chinese population is unclear. In the current study, we first analyzed the associations between these 3 single nucleotide polymorphisms (SNPs) at 4p16 and CHD risk by using our existing genome-wide scan data and found all of the 3 SNPs showed significant associations with ASD in the same direction as that observed in Cordell’s study, but not with other subtypes- ventricular septal defect (VSD) and ASD combined VSD. As these 3 SNPs were in high linkage disequilibrium (LD) in Chinese population, we selected one SNP with the lowest P value in our GWAS scan (rs16835979) to perform a replication study with additional 1,709 CHD cases with multiple phenotypes and 1,962 controls. The significant association was also observed only within the ASD subgroup, which was heterogeneous from other disease groups. In combined GWAS and replication samples, the minor allele of rs16835979 remained significant association with the risk of ASD (OR = 1.22, 95% CI = 1.08–1.38, P = 0.001). Our findings suggest that susceptibility loci of ASD identified from Cordell’s European GWAS are generalizable to Chinese population, and such investigation may provide new insights into the roles of genetic variants in the etiology of different CHD phenotypes.

Preconception considerations

Heart disease complicates 1-2% of pregnancies, and in preparation for pregnancy, these women should receive comprehensive preconception counseling. Risks to the mother and potential risks to the offspring secondary to the type and severity of maternal cardiac disease, its inheritance pattern, required medical therapy, and palliative or corrective procedures that may be needed must be considered. Life expectancy and the ability to care for a child are somber issues that must be addressed when serious cardiac conditions exist. Pregnancy is still contraindicated in women with pulmonary hypertension, severe systemic ventricular dysfunction, dilated aortopathy, and severe left-sided obstructive lesions, but advances in medical and surgical management have resulted in an increasing number of patients with cardiac disorders who are interested in pursuing pregnancy. A multidisciplinary approach can best determine whether acceptable outcomes can be expected and what management strategies may improve the prognosis for women with heart disease and their offspring.

Genetic variants at 10p11 confer risk of Tetralogy of Fallot in Chinese of Nanjing

A recent genome-wide association study (GWAS) has identified a new subset of susceptibility loci of Tetralogy of Fallot (TOF), one form of cyanotic congenital heart disease (CHD), on chromosomes 10p11, 10p14, 12q24, 13q31, 15q13 and 16q12 in Europeans. In the current study, we conducted a case-control study in a Chinese population including 1,010 CHD cases [atrial septal defect (ASD), ventricular septal defect (VSD) and TOF] and 1,962 controls to evaluate the associations of these loci with risk of CHD. We found that rs2228638 in NRP1 on 10p11 was significantly increased the risk of TOF (OR = 1.52, 95% CI = 1.13–2.04, P = 0.006), but not in other subgroups including ASD and VSD. In addition, no significant associations were observed between the other loci and the risk of ASD, VSD or TOF. Our results suggested that the genetic variants on 10p11 may serve as candidate markers for TOF susceptibility in Chinese population.

A genome-wide association study identifies two risk loci for congenital heart malformations in Han Chinese populations

Congenital heart malformation (CHM) is the most common form of congenital human birth anomaly and is the leading cause of infant mortality. Although some causative genes have been identified, little progress has been made in identifying genes in which low-penetrance susceptibility variants occur in the majority of sporadic CHM cases. To identify common genetic variants associated with sporadic non-syndromic CHM in Han Chinese populations, we performed a multistage genome-wide association study (GWAS) in a total of 4,225 CHM cases and 5,112 non-CHM controls. The GWAS stage included 945 cases and 1,246 controls and was followed by 2-stage validation with 2,160 cases and 3,866 controls. The combined analyses identified significant associations (P < 5.0 × 10⁻⁸) at 1p12 (rs2474937 near TBX15; odds ratio (OR) = 1.40; P = 8.44 × 10⁻¹⁰) and 4q31.1 (rs1531070 in MAML3; OR = 1.40; P = 4.99 × 10⁻¹²). These results extend current knowledge of genetic contributions to CHM in Han Chinese populations.