The presence of bicuspid aortic valve does not predict ventricular septal defect type

Variations in the poly-histidine repeat motif of HOXA1 contribute to bicuspid aortic valve in mouse and zebrafish

Bicuspid aortic valve (BAV), the most common cardiovascular malformation occurs in 0.5-1.2% of the population. Although highly heritable, few causal mutations have been identified in BAV patients. Here, we report the targeted sequencing of HOXA1 in a cohort of BAV patients and the identification of rare indel variants in the homopolymeric histidine tract of HOXA1. In vitro analysis shows that disruption of this motif leads to a significant reduction in protein half-life and defective transcriptional activity of HOXA1. In zebrafish, targeting hoxa1a ortholog results in aortic valve defects. In vivo assays indicates that these variants behave as dominant negatives leading abnormal valve development. In mice, deletion of Hoxa1 leads to BAV with a very small, rudimentary non-coronary leaflet. We also show that 17% of homozygous Hoxa1^-1His knock-in mice present similar phenotype. Genetic lineage tracing in Hoxa1^-/- mutant mice reveals an abnormal reduction of neural crest-derived cells in the valve leaflet, which is caused by a failure of early migration of these cells.

Bacterial Culture-Negative Acute Infective Endocarditis With Vegetation in Native Bicuspid Aortic Valve

A 51-year-old male with a past medical history of bicuspid aortic valve, hypertension, and anterior cerebral artery stroke of unclear etiology three months earlier, presented to the Emergency Department with progressive shortness of breath, hemoptysis, and night sweats. The patient's echocardiogram revealed a mobile mass greater than 1.0 cm in diameter on the bicuspid aortic valve, which was not present on the echocardiogram three months prior, during his stroke workup. Per modified Duke's criteria, this patient was found to have 'definite' infective endocarditis despite persistently negative blood cultures. The patient underwent urgent surgical aortic valve replacement and a ventricular septal defect was noted that was not seen on prior imaging. The patient was discharged on intravenous antibiotics and warfarin. The patient was able to return to his normal functional status weeks after surgery, and is continuing to exercise without limitation. This case provides an example of patients with bicuspid aortic valves having an increased propensity for developing infective endocarditis. While also highlighting the interesting intra-operative images and presentation of acute culture-negative endocarditis with vegetation, and the subsequent repair, treatment, and recovery.

Heart Failure Associated With Ventricular Septal Defect, Mitral Valve Prolapse, Non-stenotic Bicuspid Aortic Valve, and Patent Foramen Ovale

Ventricular septal defect (VSD) and bicuspid aortic valve (BAV) are the two most common congenital heart defects. BAV may occur sporadically or in association with other cardiac malformations. VSDs have decreased incidence in the adult population due to spontaneous closure. Mitral valve prolapse (MVP) and patent foramen ovale (PFO) can be associated with these conditions but the simultaneous association of these defects has never been reported in the literature. We report the case of a 35-year-old male patient with persistent VSD, BAV, and PFO associated with new-onset heart failure and MVP. We aim to study the association between the coexistence of structural heart malformations and the increased risk of heart failure.

Population-based treated prevalence, risk factors, and outcomes of bicuspid aortic valve in a pediatric Medicaid cohort

Background:

We investigated the treated prevalence of bicuspid aortic valve in a pediatric population with congenital heart disease and its incident complications.

Materials and Methods:

A 15-year retrospective data set was analyzed. Selection criteria included age ≤17 years, enrollees in the South Carolina State Medicaid program and diagnosed as having bicuspid aortic valve on one or more service visits.

Results:

The 15-year-treated prevalence of predominantly isolated bicuspid aortic valve was 2% (20/1000) of pediatric congenital heart disease cases, with a non-African American: African-American ratio of 3.5:1, and a male:female ratio of 1.6:1. Aortic stenosis (28.0%), ventricular septal defect (20.6%), and coarctation of the aorta (20.6%) were the most prevalent coexisting congenital heart lesions. Of the 378 bicuspid aortic valve cases examined, 10.3% received aortic valve repair/replacement, which was significantly more likely to be performed in children with diagnosed aortic stenosis (adjusted odds ratio = 12.90; 95% confidence interval = 5.66–29.44). Cohort outcomes over the study period indicated that 9.5% had diagnosed heart failure, but <1% had diagnosed supraventricular tachycardia, infective endocarditis, aneurysm, dissection, or death.

Conclusions:

The majority of isolated bicuspid aortic valve cases without aortic stenosis did not require surgical intervention. Outcomes for cases requiring repair/replacement were relatively benign.

Targeted next-generation sequencing identified ADAMTS5 as novel genetic substrate in patients with bicuspid aortic valve

BACKGROUND

Bicuspid Aortic Valve (BAV) is the most common congenital heart disease, affecting >1% of the general population. Up to date, three genes, NOTCH1, GATA5 and SMAD6, have been linked to the isolated form of BAV. However, potential genetic determinants remain largely unknown in most BAV patients.

MATERIAL AND METHODS

Targeted next-generation sequencing of 7 BAV candidate genes (NOTCH1, GATA5, SMAD6, NOS3, ADAMTS5, Alk2 and SMAD2) was performed in 32 BAV patients. Additional 35 BAV patients and 238 tricuspid aortic valve (TAV) patients, consisting of 107 patients from the transcatheter aortic valve implantation (TAVI) registry and 131 patients from the coronary artery disease (CAD) registry, were selected for further genotyping.

RESULTS

We found 2 rare non-synonymous variants in 2/7 genes in 3 BAV patients: one was NOTCH1:c.4297G>A and the other one was ADMTS5:c.935C>A that shared by two patients. NOTCH1:c.4297G>A has not been reported previously. ADMTS5:c.935C>A was predicted to be pathogenic by all applied algorithms. Alignment of protein sequences from all available species revealed that ADMTS5:p.Arg312Leu, produced by ADMTS5:c.935C>A, is located in a highly conserved region. The minor allele frequency of ADMTS5:c.935C>A in BAV patients was significantly higher than the matched population in TAV group (0.015 vs. 0, P=0.048).

CONCLUSION

Our results suggested that ADMTS5:c.935C>A are potentially associated with BAV. Further studies, such as large sample case-control replication test and functional research, are needed to explore the role of this rare variant in the development of BAV.

The myocardial and coronary histopathology and pathogenesis of hypoplastic left heart syndrome

Hypoplastic left heart syndrome has the greatest mortality rate among all CHDs and without palliation is uniformly fatal. Despite noble efforts, the aetiology of this syndrome is unknown and a cure remains elusive. The genetic and anatomic heterogeneity of hypoplastic left heart syndrome supports a rethinking of old hypotheses and warrants further investigation into the histological and vascular variations recognised with this syndrome. In an effort to elucidate the pathogenesis of hypoplastic left heart syndrome, this review will focus on its unique myocardial and coronary pathology as well as evaluate the association of hypoplastic left heart syndrome with the endocardial fibroelastosis reaction.

The Expanding Clinical Spectrum of Extracardiovascular and Cardiovascular Manifestations of Heritable Thoracic Aortic Aneurysm and Dissection

More than 30 heritable conditions are associated with thoracic aortic aneurysm and dissection (TAAD). Heritable syndromic conditions, such as Marfan syndrome, Loeys-Dietz syndrome, and vascular Ehlers-Danlos syndrome, have somewhat overlapping systemic features, but careful clinical assessment usually enables a diagnosis that can be validated with genetic testing. Nonsyndromic FTAAD can also occur and in 20%-25% of these probands mutations exist in genes that encode elements of the extracellular matrix, signalling pathways (especially involving transforming growth factor-β), and vascular smooth muscle cytoskeletal and contractile processes. Affected individuals with either a syndromic presentation or isolated TAAD can have mutations in the same gene. In this review we focus on the genes currently known to have causal mutations for syndromic and isolated FTAAD and outline the range of associated extracardiovascular and cardiovascular manifestations with each.

A roadmap to investigate the genetic basis of bicuspid aortic valve and its complications: insights from the International BAVCon (Bicuspid Aortic Valve Consortium)

Bicuspid aortic valve (BAV) is the most common adult congenital heart defect and is found in 0.5% to 2.0% of the general population. The term "BAV" refers to a heterogeneous group of disorders characterized by diverse aortic valve malformations with associated aortopathy, congenital heart defects, and genetic syndromes. Even after decades of investigation, the genetic determinants of BAV and its complications remain largely undefined. Just as BAV phenotypes are highly variable, the genetic etiologies of BAV are equally diverse and vary from complex inheritance in families to sporadic cases without any evidence of inheritance. In this paper, the authors discuss current concepts in BAV genetics and propose a roadmap for unraveling unanswered questions about BAV through the integrated analysis of genetic and clinical data.

Whole exome sequencing for familial bicuspid aortic valve identifies putative variants

BACKGROUND

Bicuspid aortic valve (BAV) is the most common congenital cardiovascular malformation. Although highly heritable, few causal variants have been identified. The purpose of this study was to identify genetic variants underlying BAV by whole exome sequencing a multiplex BAV kindred.

METHODS AND RESULTS

Whole exome sequencing was performed on 17 individuals from a single family (BAV=3; other cardiovascular malformation, 3). Postvariant calling error control metrics were established after examining the relationship between Mendelian inheritance error rate and coverage, quality score, and call rate. To determine the most effective approach to identifying susceptibility variants from among 54 674 variants passing error control metrics, we evaluated 3 variant selection strategies frequently used in whole exome sequencing studies plus extended family linkage. No putative rare, high-effect variants were identified in all affected but no unaffected individuals. Eight high-effect variants were identified by ≥2 of the commonly used selection strategies; however, these were either common in the general population (>10%) or present in the majority of the unaffected family members. However, using extended family linkage, 3 synonymous variants were identified; all 3 variants were identified by at least one other strategy.

CONCLUSIONS

These results suggest that traditional whole exome sequencing approaches, which assume causal variants alter coding sense, may be insufficient for BAV and other complex traits. Identification of disease-associated variants is facilitated by the use of segregation within families.

Loss of Gata5 in mice leads to bicuspid aortic valve

Bicuspid aortic valve (BAV), the leading congenital heart disease, occurs in 1%-2% of the population. Genetic studies suggest that BAV is an autosomal-dominant disease with reduced penetrance. However, only 1 gene, NOTCH1, has been linked to cases of BAV. Here, we show that targeted deletion of Gata5 in mice leads to hypoplastic hearts and partially penetrant BAV formation. Endocardial cell-specific inactivation of Gata5 led to BAV, similar to that observed in Gata5-/- mice. In all cases, the observed BAVs resulted from fusion of the right-coronary and noncoronary leaflets, the subtype associated with the more severe valve dysfunction in humans. Neither endocardial cell proliferation nor cushion formation was altered in the absence of Gata5. Rather, defective endocardial cell differentiation, resulting from the deregulation of several components of the Notch pathway and other important endocardial cell regulators, may be the underlying mechanism of disease. The results unravel a critical cell-autonomous role for endocardial Gata5 in aortic valve formation and identify GATA5 as a potential gene responsible for congenital heart disease in humans. Mice with mutated Gata5 alleles represent unique models to dissect the mechanisms underlying degenerative aortic valve disease and to develop much-needed preventive and therapeutic interventions.

Cardiovascular magnetic resonance of quinticuspid aortic valve with aortic regurgitation and dilated ascending aorta

We report a rare case of a quinticuspid aortic valve associated with regurgitation and dilation of the ascending aorta, which was diagnosed and post-surgically followed up by cardiovascular magnetic resonance and dual source computed tomography.