elastin and Aortic-Stenosis--Supravalvular

Supravalvar aortic stenosis (SVAS) is a less common but clinically important form of left ventricular outflow tract obstruction, and commonly associated with Williams syndrome (WS). SVAS outside of WS may also occur sporadically or in a familial form, often with identifiable mutations in the elastin (ELN) gene. While risk of sudden cardiac death in patients with SVAS has been extensively described in the context of WS, less is known about risk in patients with isolated SVAS. We report a case of a nonsyndromic two-year-old boy with evolving manifestations of SVAS who developed sudden cardiac arrest and death during a sedated cardiac magnetic resonance imaging study. A strong family history of SVAS was present and targeted genetic testing identified an ELN gene mutation in the boy's affected father and other paternal relatives. We review risk factors found in the literature for SCA in SVAS patients and utilize this case to raise awareness of the risk of cardiac events in these individuals even in the absence of WS or severe disease. This case also underscores the importance of genetic testing, including targeted panels specifically looking for ELN gene mutations, in all patients with SVAS even in the absence of phenotypic concerns for WS or other genetic syndromes.

Topics: Aortic Stenosis, Supravalvular; Child; Child, Preschool; Death, Sudden, Cardiac; Elastin; Humans; Magnetic Resonance Spectroscopy; Male; Mutation; Williams Syndrome

Elastic fibers provide recoil to tissues that undergo repeated deformation, such as blood vessels, lungs and skin. Composed of elastin and its accessory proteins, the fibers are produced within a restricted developmental window and are stable for decades. Their eventual breakdown is associated with a loss of tissue resiliency and aging. Rare alteration of the elastin (ELN) gene produces disease by impacting protein dosage (supravalvar aortic stenosis, Williams Beuren syndrome and Williams Beuren region duplication syndrome) and protein function (autosomal dominant cutis laxa). This review highlights aspects of the elastin molecule and its assembly process that contribute to human disease and also discusses potential therapies aimed at treating diseases of elastin insufficiency.

Topics: Aortic Stenosis, Supravalvular; Cutis Laxa; Elastin; Gene Dosage; Genetic Predisposition to Disease; Humans; Mutation; Williams Syndrome

Supravalvar aortic stenosis (SVAS) is a congenital anomaly characterized by a discrete or diffuse narrowing of the ascending aorta. It may also be associated with right-ventricular outflow tract obstruction, aortic valve pathology and coronary ostial stenosis. While present in both familial and sporadic forms, it demonstrates a strong association with William-Beuren syndrome, both being anomalies associated with defects in the elastin gene. In this article, the authors have discussed the etiology, morphology, clinical presentation and genetic basis of SVAS. Various surgical approaches, both conventional and recent, have been discussed and demonstrated with the aid of diagrams. Single-, two- and three-sinus methods have been presented, along with a comparative analysis of early results, associated procedures, late mortality and reoperation. In conclusion, the authors have described their institutional experience of more than 40 years in the surgical management of SVAS.

Topics: Animals; Aortic Stenosis, Supravalvular; Aortic Valve; Coronary Stenosis; Elastin; Humans; Reoperation; Ventricular Outflow Obstruction; Williams Syndrome

Supravalvular aortic stenosis is a systemic elastin (ELN) arteriopathy that disproportionately affects the supravalvular aorta. ELN arteriopathy may be present in a nonsyndromic condition or in syndromic conditions such as Williams-Beuren syndrome. The anatomic findings include congenital narrowing of the lumen of the aorta and other arteries, such as branches of pulmonary or coronary arteries. Given the systemic nature of the disease, accurate evaluation is recommended to establish the degree and extent of vascular involvement and to plan appropriate interventions, which are indicated whenever hemodynamically significant stenoses occur. ELN arteriopathy is genetically heterogeneous and occurs as a consequence of haploinsufficiency of the ELN gene on chromosome 7q11.23, owing to either microdeletion of the entire chromosomal region or ELN point mutations. Interestingly, there is a prevalence of premature termination mutations resulting in null alleles among ELN point mutations. The identification of the genetic defect in patients with supravalvular aortic stenosis is essential for a definitive diagnosis, prognosis, and genetic counseling.

Topics: Aorta; Aortic Stenosis, Supravalvular; Diagnosis, Differential; Elastin; Humans; Syndrome; Ultrasonography

Supravalvar aortic stenosis (SVAS) is a rare anomaly of the aortic root caused by a genetically based deficiency in elastin production. Concomitant primary and secondary cardiovascular lesions complicate surgical management and impact early and late outcomes. Because SVAS is a rare lesion, surgical series are relatively small and span lengthy time periods. Consequently, risk factors that influence early and late outcomes are not well defined. Patients who come to surgery during infancy are particularly challenging, but little attention has been directed as to whether or not young age influences outcomes. This review suggests that complicating associated features of elastin arteriopathy are more prevalent in patients who require relief of SVAS during infancy, and that concomitant lesions significantly increase the difficulty and risk of treating younger patients with SVAS.

Topics: Angiography; Aortic Stenosis, Supravalvular; Cardiac Surgical Procedures; Coronary Stenosis; Elastin; Female; Follow-Up Studies; Humans; Infant; Infant, Newborn; Male; Postoperative Complications; Rare Diseases; Risk Assessment; Severity of Illness Index; Survival Rate; Treatment Outcome

Elastic fibres are a major class of extracellular matrix fibres that are abundant in dynamic connective tissues such as arteries, lungs, skin and ligaments. Their structural role is to endow tissues with elastic recoil and resilience. They also act as an important adhesion template for cells, and they regulate growth factor availability. Mutations in major structural components of elastic fibres, especially elastin, fibrillins and fibulin-5, cause severe, often life-threatening, heritable connective tissue diseases such as Marfan syndrome, supravalvular aortic stenosis and cutis laxa. Elastic-fibre function is also frequently compromised in damaged or aged elastic tissues. The ability to regenerate or engineer elastic fibres and tissues remains a significant challenge, requiring improved understanding of the molecular and cellular basis of elastic-fibre biology and pathology, and ability to regulate the spatiotemporal expression and assembly of its molecular components.

Topics: Animals; Aortic Stenosis, Supravalvular; Connective Tissue; Connective Tissue Diseases; Elastic Tissue; Elastin; Extracellular Matrix; Extracellular Matrix Proteins; Fibrillins; Humans; Marfan Syndrome; Mice; Microfilament Proteins; Models, Biological; Recombinant Proteins; Time Factors; Tissue Distribution

Elastin is synthesized and secreted by vascular smooth muscle cells and is the major extracellular matrix component deposited in the arterial wall. When last reviewed by this journal in 1994, the link between elastin and a rare occlusive vascular disease had just been established. Since that time, it has become increasingly clear that elastin is a critical autocrine factor that maintains vascular homeostasis through a combination of biomechanical support and biologic signaling. This review examines the complexity of elastin-smooth muscle cell interactions, and how new insights may impact understanding of the pathogenesis and treatment of vascular disease.

Topics: Animals; Aortic Stenosis, Supravalvular; Autocrine Communication; Blood Vessels; Cell Line; Elastin; Homeostasis; Mice; Muscle, Smooth, Vascular; Phenotype; Vascular Diseases; Williams Syndrome

The underlying cause of congenital supravalvular aortic stenosis (SVAS) has recently been identified as a loss-of function mutation of the elastin gene on chromosome 7q11.23, resulting in an obstructive arteriopathy of varying severity, which is most prominent at the aortic sinutubular junction. The generalized nature of the disease explains the frequent association with stenoses of systemic and pulmonary arteries. Furthermore, localization of the supravalvular stenosis at the level of the commissures of the aortic valve has important implications for both aortic valve function and coronary circulation. This review summarizes the recent advances with regard to the pathogenesis of SVAS and describes the multitude of clinically relevant pathologic features other that the mere 'supra-aortic' narrowing that have important implications for surgical therapy.

Topics: Aorta; Aortic Stenosis, Supravalvular; Constriction, Pathologic; Coronary Circulation; Elastin; Humans; Pulmonary Artery; Williams Syndrome

The elastic fibres endow extensible tissues with resiliency, such as in blood vessels, heart, skin and lung. Elastic fibres are made of microfibrils, and mainly elastin (90%) which provides the fibre with elasticity. Beside the biomechanical role of elastin, a close correlation between elastin and elastic fibre network disorganisation and vascular smooth muscle cell (VSMC) growth disregulation has been known for several years through the description and study of several human or animal polyfeatured or obstructive vascular diseases, such as supravalvular aortic stenosis (SVAS) and Williams syndrome (WS), both related to heterozygous mutations or deletion in the elastin gene. The study of mice knock-out for the elastin gene (homozygous or heterozygous) leads to think that elastin should now be seen as an important elastic component providing extensible tissues with resiliency, as well as a major developmental regulator of VSMC life cycle and smooth muscle tissue organisation. Further developments in the area of preventive therapy of SVAS, WS or other inherited muscular disorders are likely to arise from these results.

Topics: Animals; Aortic Stenosis, Supravalvular; Coronary Vessels; Elastic Tissue; Elasticity; Elastin; Genotype; Humans; Infant, Newborn; Lung; Mice; Mice, Knockout; Muscle, Smooth, Vascular; Skin; Williams Syndrome

Supravalvular aortic stenosis (SVAS), Marfan syndrome (MFS) and Ehlers-Danlos syndrome type IV (EDS IV) are three clinical entities characterized by vascular abnormalities that result from mutations of structural components of the extracellular matrix (ECM). Analyses of naturally occurring human mutations and of artificially generated deficiencies in the mouse have provided insights into the pathogenesis of these heritable disorders of the connective tissue. SVAS is associated with haploinsufficiency of elastin, one of the two major components of the elastic fibers. SVAS is characterized by narrowing of the arterial lumen due to the failure of regulation of cellular proliferation and matrix deposition. Mutations in fibrillin 1 are the cause of dissecting aneurysm leading to rupture of the ascending aorta. Fibrillin-1 is the building block of the microfibrils that span the entire thickness of the aortic wall and are a major component of the elastic fibers that reside in the medial layer. The vascular hallmark of EDS IV is rupture of large vessels. The phenotype is caused by mutations in type III collagen. The mutations ultimately affect the overall architecture of the collagenous network and the biomechanical properties of the adventitial layer of the vessel wall. Altogether, these genotype-phenotype correlations document the diversified contributions of distinct extracellular macroaggregates to the assembly and function of the vascular matrix.

Topics: Animals; Aortic Stenosis, Supravalvular; Blood Vessels; Collagen; Ehlers-Danlos Syndrome; Elastin; Extracellular Matrix; Extracellular Matrix Proteins; Fibrillin-1; Fibrillins; Humans; Marfan Syndrome; Mice; Microfibrils; Microfilament Proteins; Mutation; Vascular Diseases

Over the last decade, a considerable amount of new information has emerged describing the protein components of elastic fibers. It is now evident that elastic fibers are complex extracellular matrix polymers, composed of at least 19 different proteins that comprise both the microfibrillar and the amorphous components of elastic fibers. Mutations in three of the genes encoding the most abundant of these elastic fiber proteins result in a broad spectrum of elastic tissue phenotypes, ranging from skeletal and skin abnormalities to vascular and ocular defects. The following disorders will be discussed in this review: supravalvular aortic stenosis; Williams-Beuren syndrome; cutis laxa; Marfan syndrome; ectopia lentis; familial thoracic aortic aneurysms and dissections; MASS syndrome; isolated skeletal features of Marfan syndrome; Shprintzen-Goldberg syndrome; and congenital contractural arachnodactyly.

Topics: Aortic Stenosis, Supravalvular; Connective Tissue Diseases; Cutis Laxa; Elastic Tissue; Elastin; Extracellular Matrix Proteins; Fibrillins; Humans; Marfan Syndrome; Microfilament Proteins; Mutation; Phenotype

The inability to study appropriate human tissues at various stages of development has precluded the elaboration of a thorough understanding of the pathogenic mechanisms leading to diseases linked to mutations in genes for elastic fiber proteins. Recently, new insights have been gained by studying mice harboring targeted mutations in the genes that encode fibrillin-1 and elastin. These genes have been linked to Marfan syndrome (MFS) and supravalvular aortic stenosis (SVAS), respectively. For fibrillin-1, mouse models have revealed that phenotype is determined by the degree of functional impairment. The haploinsufficiency state or the expression of low levels of a product with dominant-negative potential from one allele is associated with mild phenotypes with a predominance of skeletal features. Exuberant expression of a dominant-negative-acting protein leads to the more severe MFS phenotype. Mice harboring targeted deletion of the elastin gene (ELN) show many of the features of SVAS in humans, including abnormalities in the vascular wall and altered hemodynamics associated with changes in wall compliance. The genetically altered mice suggest that SVAS is predominantly a disease of haploinsufficiency. These studies have underscored the prominent role of the elastic matrix in the morphogenesis and homeostasis of the vessel wall.

Topics: Animals; Aortic Stenosis, Supravalvular; Connective Tissue Diseases; Disease Models, Animal; Elastin; Extracellular Matrix Proteins; Fibrillin-1; Fibrillins; Humans; Marfan Syndrome; Mice; Microfilament Proteins; Models, Genetic; Mutation

Three clinical conditions displaying phenotypic overlap have been linked to mutation or deletion of the elastin gene at 7q11.23. Supravalvar aortic stenosis, an autosomal dominant disorder characterized by elastin arteriopathy, is caused by mutation or intragenic deletions of ELN resulting in loss of function. Autosomal dominant cutis laxa, a primarily cutaneous condition, is the result of frameshift mutations at ELN that cause a dominant-negative effect on elastic fiber structure. Williams syndrome, a neurodevelopmental disorder is due to a 1.5 Mb deletion that includes ELN and at least 15 contiguous genes. The disorder is characterized by dysmorphic facies, mental retardation or learning difficulties, elastin arteriopathy, a unique cognitive profile of relative strength in auditory rote memory and language and extreme weakness in visuospatial constructive cognition, and a typical personality that includes overfriendliness, anxiety, and attention problems. The understanding of these disorders has progressed from phenotypic description to identification of causative mutations and insight into pathogenetic mechanisms for some aspects of the phenotype.

Topics: Aortic Stenosis, Supravalvular; Cognition Disorders; Cutis Laxa; Elastin; Humans; Language Development Disorders; Memory; Personality; Phenotype; Sequence Deletion; Williams Syndrome

To characterise the ocular manifestations of Williams-Beuren syndrome (WBS) and compare these to patients with isolated elastin mediated supravalvular aortic stenosis (SVAS).. Fifty-seven patients with a diagnosis of WBS and five with SVAS underwent comprehensive ophthalmic evaluation at the National Institutes of Health from 2017 to 2020, including best-corrected visual acuity, slit-lamp biomicroscopy, optical biometry, dilated fundus examination, optical coherence tomography and colour fundus imaging.. Mean age of the 57 WBS patients was 20.3 years (range 3-60 years). Best-corrected visual acuity ranged from 20/20 to 20/400 with mean spherical equivalent near plano OU. Twenty-four eyes (21.8%) had an axial length (AL) less than 20.5 mm and 38 eyes (34.5%) had an AL measuring 20.5-22.0 mm. Stellate iris and retinal arteriolar tortuosity were noted in 30 (52.6%) and 51 (89.5%) WBS patients, respectively. Novel retinal findings in WBS included small hypopigmented retinal deposits (OD 29/57, OS 27/57) and broad foveal pit contour (OD 44/55, OS 42/51). Of the five patients with SVAS, none had stellate iris or broad foveal pit contour while 2/5 had retinal arteriolar tortuosity.. WBS is a complex multisystem genetic disorder with diverse ophthalmic findings that differ from those seen in isolated elastin mediated SVAS. These results suggest other genes within the WBS critical region, aside from

Topics: Adolescent; Adult; Aortic Stenosis, Supravalvular; Child; Child, Preschool; Elastin; Humans; Middle Aged; Phenotype; Tomography, Optical Coherence; Williams Syndrome; Young Adult

Elastic fibers are extracellular macromolecules that provide resilience and elastic recoil to elastic tissues and organs in vertebrates. They are composed of an elastin core surrounded by a mantle of fibrillin-rich microfibrils and are essentially produced during a relatively short period around birth in mammals. Thus, elastic fibers have to resist many physical, chemical, and enzymatic constraints occurring throughout their lives, and their high stability can be attributed to the elastin protein. Various pathologies, called elastinopathies, are linked to an elastin deficiency, such as non-syndromic supravalvular aortic stenosis (SVAS), Williams-Beuren syndrome (WBS), and autosomal dominant cutis laxa (ADCL). To understand these diseases, as well as the aging process related to elastic fiber degradation, and to test potential therapeutic molecules in order to compensate for elastin impairments, different animal models have been proposed. Considering the many advantages of using zebrafish, we here characterize a zebrafish mutant for the

Topics: Animals; Aortic Stenosis, Supravalvular; Cutis Laxa; Elastin; Heart Valves; Williams Syndrome; Zebrafish

Elastin-driven genetic diseases are a group of complex diseases driven by elastin protein insufficiency and dominant-negative production of aberrant protein, including supravalvular aortic stenosis (SVAS) and autosomal dominant cutis laxa. Here, a Chinese boy with a novel nonsense mutation in the ELN gene is reported.. We report a 1-year-old boy who presented with exercise intolerance, weight growth restriction with age, a 1-year history of heart murmur, and inguinal hernia. Gene sequencing revealed a novel nonsense mutation in the ELN gene (c.757 C > T (p.Gln253Ter), NM_000501.4). Due to severe branch pulmonary artery stenosis, the reconstruction of the branch pulmonary artery with autologous pericardium was performed. The inguinal hernia repair was performed 3 months postoperatively. After six months of outpatient follow-up, the child recovered well, gained weight with age, and had no special clinical symptoms.. We identified a de novo nonsense mutation in the ELN gene leading to mild SVAS and severe branch pulmonary artery stenosis. A new phenotype of inguinal hernia was also needed to be considered for possible association with the ELN gene. Still, further confirmation will be necessary.

Topics: Aortic Stenosis, Supravalvular; Child; Codon, Nonsense; Elastin; Hernia, Inguinal; Humans; Infant; Male; Mutation; Stenosis, Pulmonary Artery

Obstructive arterial diseases, including supravalvular aortic stenosis (SVAS), atherosclerosis, and restenosis, share 2 important features: an abnormal or disrupted elastic lamellae structure and excessive smooth muscle cells (SMCs). However, the relationship between these pathological features is poorly delineated. SVAS is caused by heterozygous loss-of-function, hypomorphic, or deletion mutations in the elastin gene (ELN), and SVAS patients and elastin-mutant mice display increased arterial wall cellularity and luminal obstructions. Pharmacological treatments for SVAS are lacking, as the underlying pathobiology is inadequately defined. Herein, using human aortic vascular cells, mouse models, and aortic samples and SMCs derived from induced pluripotent stem cells of ELN-deficient patients, we demonstrated that elastin insufficiency induced epigenetic changes, upregulating the NOTCH pathway in SMCs. Specifically, reduced elastin increased levels of γ-secretase, activated NOTCH3 intracellular domain, and downstream genes. Notch3 deletion or pharmacological inhibition of γ-secretase attenuated aortic hypermuscularization and stenosis in Eln-/- mutants. Eln-/- mice expressed higher levels of NOTCH ligand JAGGED1 (JAG1) in aortic SMCs and endothelial cells (ECs). Finally, Jag1 deletion in SMCs, but not ECs, mitigated the hypermuscular and stenotic phenotype in the aorta of Eln-/- mice. Our findings reveal that NOTCH3 pathway upregulation induced pathological aortic SMC accumulation during elastin insufficiency and provide potential therapeutic targets for SVAS.

Topics: Amyloid Precursor Protein Secretases; Animals; Aorta; Aortic Stenosis, Supravalvular; Constriction, Pathologic; Elastin; Endothelial Cells; Humans; Jagged-1 Protein; Mice; Receptor, Notch3

Williams-Beuren syndrome (WBS) is a rare disorder caused by a heterozygous deletion of 26-28 contiguous genes that affects the brain and cardiovascular system. Here, we investigated whether WBS affects aortic structure and function in the complete deletion (CD) mouse model harbouring the most common deletion found in WBS patients. Thoracic aortas from 3-4 months-old male CD mice and wild-type littermates were mounted in wire myographs or were processed for histomorphometrical analysis. Nitric oxide synthase (NOS) isoforms and oxidative stress levels were assessed. Ascending aortas from young adult CD mice showed moderate (50%) luminal stenosis, whereas endothelial function and oxidative stress were comparable to wild-type. CD mice showed greater contractions to KCl. However, α1-adrenergic contractions to phenylephrine, but not with a thromboxane analogue, were compromised. Decreased phenylephrine responses were not affected by selective inducible NOS blockade with 1400 W, but were prevented by the non-selective NOS inhibitor L-NAME and the selective neuronal NOS inhibitor SMTC. Consistently, CD mice showed increased neuronal NOS expression in aortas. Overall, aortic stenosis in CD mice coexists with excessive nNOS-derived NO signaling that compromises ascending aorta α1-adrenergic contractions. We suggest that increased neuronal NOS signaling may act as a physiological 'brake' against the detrimental effects of stenosis.

Topics: Animals; Aorta, Thoracic; Aortic Stenosis, Supravalvular; Disease Models, Animal; Elastin; Endothelium, Vascular; Ethidium; Male; Mice, Mutant Strains; Nitric Oxide; Nitric Oxide Synthase Type I; Oxidative Stress; Phenylephrine; Receptors, Adrenergic, alpha-1; Williams Syndrome

Supravalvular aortic stenosis (SVAS) is a narrowing of the aorta caused by elastin (ELN) haploinsufficiency. SVAS severity varies among patients with Williams-Beuren syndrome (WBS), a rare disorder that removes one copy of ELN and 25-27 other genes. Twenty percent of children with WBS require one or more invasive and often risky procedures to correct the defect while 30% have no appreciable stenosis, despite sharing the same basic genetic lesion. There is no known medical therapy. Consequently, identifying genes that modify SVAS offers the potential for novel modifier-based therapeutics. To improve statistical power in our rare-disease cohort (N = 104 exomes), we utilized extreme-phenotype cohorting, functional variant filtration and pathway-based analysis. Gene set enrichment analysis of exome-wide association data identified increased adaptive immune system variant burden among genes associated with SVAS severity. Additional enrichment, using only potentially pathogenic variants known to differ in frequency between the extreme phenotype subsets, identified significant association of SVAS severity with not only immune pathway genes, but also genes involved with the extracellular matrix, G protein-coupled receptor signaling and lipid metabolism using both SKAT-O and RQTest. Complementary studies in Eln+/-; Rag1-/- mice, which lack a functional adaptive immune system, showed improvement in cardiovascular features of ELN insufficiency. Similarly, studies in mixed background Eln+/- mice confirmed that variations in genes that increase elastic fiber deposition also had positive impact on aortic caliber. By using tools to improve statistical power in combination with orthogonal analyses in mice, we detected four main pathways that contribute to SVAS risk.

Topics: Adolescent; Animals; Aortic Stenosis, Supravalvular; Child, Preschool; Constriction, Pathologic; Disease Models, Animal; Elastin; Exome Sequencing; Haploinsufficiency; Homeodomain Proteins; Humans; Male; Mice; Risk Factors; Williams Syndrome

Elastin insufficiency causes recurrent vascular stenoses. Hemizygous deletion of the elastin gene (. Patients (81 WBS, 42 nonsyndromic SVAS) with cardiovascular disease were included in this retrospective single center study. Freedom from surgical and catheter interventions and reinterventions was compared. Vascular tissue from 8 patients and 6 controls was analyzed for arterial wall architecture.. Patients with nonsyndromic SVAS presented at a younger age (median 0.3 [0.4-0.7] years) compared with patients with WBS (1.3 [0.2-3.0] years) and had lower freedom from surgical/catheter interventions compared with patients with WBS, with median event-free survival 1.1 (0.3-5.9) versus 4.7 (2.4-13.3) years, respectively (hazard ratio, 1.62 [95% CI, 1.02-2.56];. Patients with nonsyndromic SVAS require early and more frequent vascular and valvular interventions and reinterventions, in particular for concomitant valvar aortic stenosis compared with patients with WBS. This provides important prognostic information to guide counseling of affected families with cardiovascular disease and may guide primary intervention strategies based on predicted risk of restenosis.

Topics: Adolescent; Aortic Stenosis, Supravalvular; Arteries; Cardiovascular System; Catheters; Child; Child, Preschool; Elastin; Female; Humans; Infant; Kaplan-Meier Estimate; Male; Phenotype; Pulmonary Valve Stenosis; Severity of Illness Index; Vascular Diseases; Williams Syndrome

Supravalvular aortic stenosis (SVAS) is one of the congenital cardiovascular diseases characterized by stenosis of the aorta. The stenotic lesions occur anywhere above the aortic valve in the aortic tree as well as pulmonary arteries and eventually leads to circulatory failure. The disease gene has been identified on the elastin gene (ELN) and two types of SVAS have been categorized; a familial type and an isolated type with the de novo mutation.. Fluorescent In situ hybridization (FISH) analysis and gene sequencing were performed in a two-generation family in which severe form of SVAS was diagnosed.. None of the patients tested showed microdeletion of ELN, LIMK1, and D7S613. A novel nonsense mutation of ELN (c.160G>T (p.(Gly54*)), RNA not analyzed) was found in exon 3 in three members; two of them died suddenly due to rapid progression of SVAS with possible arrhythmia in early infancy. A point mutation in the 5' untranslated region, which was previously suggested to be associated with SVAS, did not co-segregate with the SVAS phenotype and found to be SNPs.. Our report shows a broad spectrum of clinical features in family members sharing the identical mutations, suggesting a potential contribution of modifier gene(s) or interactions with environmental factors.

Topics: Adult; Aortic Stenosis, Supravalvular; Asian People; Elastin; Family Health; Female; Humans; In Situ Hybridization, Fluorescence; Infant, Newborn; Japan; Male; Pedigree; Point Mutation

Supravalvular aortic stenosis (SVAS) is a congenital heart disease affecting approximately 1:25,000 live births. SVAS may occur sporadically, be inherited in an autosomal dominant manner, or be associated with Williams-Beuren syndrome, a complex developmental disorder caused by a microdeletion of chromosome 7q11.23. ELN on 7q11.23, which encodes elastin, is the only known gene to be recurrently mutated in less than half of SVAS patients.. Whole-exome sequencing (WES) was performed for seven familial SVAS families to identify other causative gene mutations of SVAS.. Three truncating mutations and three intragenic deletions affecting ELN were identified, yielding a diagnostic efficiency of 6/7 (85%). The deletions, which explained 3/7 of the present cohort, spanned 1-29 exons, which might be missed in the course of mutational analysis targeting point mutations. The presence of such deletions was validated by both WES-based copy number estimation and multiplex ligation-dependent probe amplification analyses, and their pathogenicity was reinforced by co-segregation with clinical presentations.. The majority of familial SVAS patients appear to carry ELN mutations, which strongly indicates that elastin is the most important causative gene for SVAS. The frequency of intragenic deletions highlights the need for quantitative tests to analyze ELN for efficient genetic diagnosis of SVAS.

Topics: Aortic Stenosis, Supravalvular; DNA; DNA Mutational Analysis; Elastin; Exome Sequencing; Female; Humans; Male; Pedigree; Point Mutation

Topics: Aortic Diseases; Aortic Stenosis, Supravalvular; Arterial Occlusive Diseases; Elastin; Humans; Williams Syndrome

Pathogenic germline mutations in ELN can be detected in patients with supravalvular aortic stenosis. The mutation might occur de novo or be inherited following an autosomal dominant pattern of inheritance. In this report we describe a three-generation family suffering from supravalvular aortic stenosis, various other arterial stenoses, sudden death, and intracranial aneurysms. A frameshift mutation in exon 12, not described before, was detected in the affected family members. This report emphasises the importance of family history, genetic counselling, and demonstrates the great variability in the phenotype within a single SVAS family.

Topics: Adult; Aortic Stenosis, Supravalvular; Elastin; Exons; Female; Frameshift Mutation; Genetic Counseling; Germ-Line Mutation; Humans; Intracranial Aneurysm; Male; Middle Aged; Pedigree; Phenotype

The aorta is the largest artery in the body, yet processes underlying aortic pathology are poorly understood. The arterial media consists of circumferential layers of elastic lamellae and smooth muscle cells (SMCs), and many arterial diseases are characterized by defective lamellae and excess SMCs; however, a mechanism linking these pathological features is lacking. In this study, we use lineage and genetic analysis, pharmacological inhibition, explant cultures, and induced pluripotent stem cells (iPSCs) to investigate supravalvular aortic stenosis (SVAS) patients and/or elastin mutant mice that model SVAS. These experiments demonstrate that multiple preexisting SMCs give rise to excess aortic SMCs in elastin mutants, and these SMCs are hyperproliferative and dedifferentiated. In addition, SVAS iPSC-derived SMCs and the aortic media of elastin mutant mice and SVAS patients have enhanced integrin β3 levels, activation, and downstream signaling, resulting in SMC misalignment and hyperproliferation. Reduced β3 gene dosage in elastin-null mice mitigates pathological aortic muscularization, SMC misorientation, and lumen loss and extends survival, which is unprecedented. Finally, pharmacological β3 inhibition in elastin mutant mice and explants attenuates aortic hypermuscularization and stenosis. Thus, integrin β3-mediated signaling in SMCs links elastin deficiency and pathological stenosis, and inhibiting this pathway is an attractive therapeutic strategy for SVAS.

Topics: Animals; Aorta; Aortic Stenosis, Supravalvular; Cell Dedifferentiation; Cell Proliferation; Down-Regulation; Elastin; Gene Dosage; Humans; Integrin beta3; Mice, Inbred C57BL; Molecular Targeted Therapy; Muscle, Smooth, Vascular; Mutation; Myocytes, Smooth Muscle; Myosin Heavy Chains; Signal Transduction

Williams-Beuren syndrome (WBS) is a congenital disorder, which involves the heterozygous deletion of the elastin gene and other genes on chromosome 7. Clinical symptoms that are associated with hemizygosity of the essential extracellular matrix protein elastin include premature aging of the skin and supravalvular aortic stenosis. However, only little is known about the molecular basis of structural abnormalities in the connective tissue of WBS patients. Therefore, for the first time this study aimed to systematically characterize and compare the structure and amount of elastin present in skin and aortic tissue from WBS patients and healthy individuals. Elastin fibers were isolated from tissue biopsies, and it was found that skin of WBS patients contains significantly less elastin compared to skin of healthy individuals. Scanning electron microscopy and mass spectrometric measurements combined with bioinformatics data analysis were used to investigate the molecular-level structure of elastin. Scanning electron microscopy revealed clear differences between WBS and healthy elastin. With respect to the molecular-level structure, it was found that the proline hydroxylation degree differed between WBS and healthy elastin, while the tropoelastin isoform appeared to be the same. In terms of cross-linking, no differences in the content of the tetrafunctional cross-links desmosine and isodesmosine were found between WBS and healthy elastin. However, principal component analysis revealed differences between enzymatic digests of elastin from healthy probands and WBS patients, which indicates differing susceptibility toward enzymatic cleavage. Overall, the study contributes to a better understanding of the correlation between genotypic and elastin-related phenotypic features of WBS patients. © 2016 Wiley Periodicals, Inc.

Topics: Adult; Aged, 80 and over; Aging; Aorta; Aortic Stenosis, Supravalvular; Biopsy; Elastin; Female; Genetic Association Studies; Humans; Male; Microscopy, Electron, Scanning; Middle Aged; Tropoelastin; Williams Syndrome

Patients with elastin deficiency attributable to gene mutation (supravalvular aortic stenosis) or chromosomal microdeletion (Williams syndrome) are characterized by obstructive arteriopathy resulting from excessive smooth muscle cell (SMC) proliferation, mural expansion, and inadequate vessel size. We investigated whether rapamycin, an inhibitor of the cell growth regulator mammalian target of rapamycin (mTOR) and effective against other SMC proliferative disorders, is of therapeutic benefit in experimental models of elastin deficiency.. As previously reported, Eln(-/-) mice demonstrated SMC hyperplasia and severe stenosis of the aorta, whereas Eln(+/-) mice exhibited a smaller diameter aorta with more numerous but thinner elastic lamellae. Increased mTOR signaling was detected in elastin-deficient aortas of newborn pups that was inhibited by maternal administration of rapamycin. mTOR inhibition reduced SMC proliferation and aortic obstruction in Eln(-/-) pups and prevented medial hyperlamellation in Eln(+/-) weanlings without compromising aortic size. However, rapamycin did not prolong the survival of Eln(-/-) pups, and it retarded the somatic growth of juvenile Eln(+/-) and Eln(+/+) mice. In cell cultures, rapamycin inhibited prolonged mTOR activation and enhanced proliferation of SMC derived from patients with supravalvular aortic stenosis and with Williams syndrome.. mTOR inhibition may represent a pharmacological strategy to treat diffuse arteriopathy resulting from elastin deficiency.

Topics: Adult; Animals; Aortic Stenosis, Supravalvular; Arterial Occlusive Diseases; Cell Proliferation; Elastin; Female; Humans; Male; Mice; Mice, Inbred C57BL; Middle Aged; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Williams Syndrome

Haploinsufficiency of the elastin gene (ELN) on 7q11.23 is responsible for supravalvular aortic stenosis (SVAS) and other arteriopathies in patients with Williams-Beuren syndrome (WBS). These defects occur with variable penetrance and expressivity, but the basis of this is unknown. To determine whether DNA variations in ELN could serve as genetic modifiers, we sequenced the 33 exons and immediately surrounding sequence of the ELN gene (9,455 bp of sequence) in 49 DNAs from patients with WBS and compared cardiovascular phenotypes. Four missense, and four novel intronic variants were identified from a total of 24 mostly intronic single nucleotide variations and one indel. Two missense changes were present in one patient each, one published, p.Gly610Ser in exon 27 (MAF, 0.003) and one novel, p.Cys714Tyr, in exon 33 (MAF, 0.001), were rare in the general population. To identify a statistical association between the variants identified here and cardiovascular phenotypes a larger cohort would be needed.

Topics: Adolescent; Aortic Stenosis, Supravalvular; Child; Child, Preschool; DNA Mutational Analysis; Elastin; Female; Gene Frequency; Genetic Association Studies; Genetic Variation; Haploinsufficiency; Humans; Infant; Male; Middle Aged; Phenotype; Polymorphism, Single Nucleotide; Ultrasonography; Williams Syndrome

The goal of this study was to determine whether antagonizing microRNA (miR)-29 enhances elastin (ELN) levels in cells and tissues lacking ELN.. miR-29 mimics reduced ELN levels in fibroblasts and smooth muscle cells, whereas miR-29 inhibition increased ELN levels. Antagonism of miR-29 also increased ELN levels in cells from patients haploinsufficient for ELN and in bioengineered human vessels.. miR-29 antagonism may promote increased ELN levels during conditions of ELN deficiencies.

Topics: Aortic Stenosis, Supravalvular; Arteries; Blood Vessel Prosthesis; Cells, Cultured; Compliance; Elastin; Fibroblasts; Haploinsufficiency; Humans; MicroRNAs; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; RNA Interference; Tissue Engineering; Transfection; Up-Regulation

Williams-Beuren syndrome (WBS) and supravalvular aortic stenosis (SVAS) are genetic syndromes marked by the propensity to develop severe vascular stenoses. Vascular lesions in both syndromes are caused by haploinsufficiency of the elastin gene. We used these distinct genetic syndromes as models to evaluate the feasibility of using engineered zinc-finger protein transcription factors (ZFPs) to achieve compensatory expression of haploinsufficient genes by inducing augmented expression from the remaining wild-type allele. For complex genes with multiple splice variants, this approach could have distinct advantages over cDNA-based gene replacement strategies. Targeting the elastin gene, we show that transcriptional activation by engineered ZFPs can induce compensatory expression from the wild-type allele in the setting of classic WBS and SVAS genetic mutations, increase elastin expression in wild-type cells, induce expression of the major elastin splice variants, and recapitulate their natural stoichiometry. Further, we establish that transcriptional activation of the mutant allele in SVAS does not overcome nonsense-mediated decay, and thus ZFP-mediated transcriptional activation is not likely to induce production of a mutant protein, a crucial consideration. Finally, we show in bioengineered blood vessels that ZFP-mediated induction of elastin expression is capable of stimulating functional elastogenesis. Haploinsufficiency is a common mechanism of genetic disease. These findings have significant implications for WBS and SVAS, and establish that haploinsufficiency can be overcome by targeted transcriptional activation without inducing protein expression from the mutant allele.

Topics: Alleles; Aortic Stenosis, Supravalvular; Cell Line; Cell Movement; Cell Proliferation; Dosage Compensation, Genetic; Elastin; Gene Expression; Gene Expression Regulation; Haploinsufficiency; Humans; Mutation; Nonsense Mediated mRNA Decay; Organ Specificity; Protein Engineering; Transcriptional Activation; Williams Syndrome; Zinc Fingers

Supravalvular aortic stenosis (SVAS) is a congenital narrowing of the ascending aorta, which can occur sporadically as an autosomal dominant condition or as one component of the Williams-Beuren syndrome, a complex developmental genomic disorder associated with cardiovascular, neurobehavioral, craniofacial, and metabolic abnormalities, caused by a microdeletion at 7q11.23. We report the identification of seven novel mutations within the elastin gene in 31 familial and sporadic cases of nonsyndromic SVAS. Five are frameshift mutations within the coding region of the ELN gene that result in premature stop codons (PTCs); the other two mutations abolish the donor splice site of introns 3 and 28, respectively, and are predicted to alter splicing efficiency resulting in the generation of a PTC within the same introns of the gene. In vitro analysis using minigenes and cycloheximide showed that some selected frameshift mutant alleles are substrates of nonsense-mediated mRNA decay (NMD), confirming that the functional haploinsufficiency of the ELN gene is the main pathomechanism underlying SVAS. Interestingly, molecular analysis on patient fibroblasts showed that the c.2044+5G>C mutant allele encodes for an aberrant shorter form of the elastin polypeptide that may hamper the normal assembly of elastin fibers in a dominant-negative manner.

Topics: Aortic Stenosis, Supravalvular; Base Sequence; Cell Line; Cohort Studies; Cycloheximide; DNA Mutational Analysis; Elastin; Gene Expression Regulation; Humans; Molecular Sequence Data; Mutation; RNA Splice Sites; RNA, Messenger

Even though elastin and fibrillin-1 are the major structural components of elastic fibers, mutations in elastin and fibrillin-1 lead to narrowing of large arteries in supravalvular aortic stenosis and dilation of the ascending aorta in Marfan syndrome, respectively. A genetic approach was therefore used here to distinguish the differential contributions of elastin and fibrillin-1 to arterial development and compliance.. Key parameters of cardiovascular function were compared among adult mice haploinsufficient for elastin (Eln(+/-)), fibrillin-1 (Fbn1(+/-)), or both proteins (dHet). Physiological and morphological comparisons correlate elastin haploinsufficiency with increased blood pressure and vessel length and tortuosity in dHet mice, and fibrillin-1 haploinsufficiency with increased aortic diameter in the same mutant animals. Mechanical tests confirm that elastin and fibrillin-1 impart elastic recoil and tensile strength to the aortic wall, respectively. Additional ex vivo analyses demonstrate additive and overlapping contributions of elastin and fibrillin-1 to the material properties of vascular tissues. Lastly, light and electron microscopy evidence implicates fibrillin-1 in the hypertension-promoted remodeling of the elastin-deficient aorta.. These results demonstrate that elastin and fibrillin-1 have both differential and complementary roles in arterial wall formation and function, and advance our knowledge of the structural determinants of vascular physiology and disease.

Topics: Animals; Aortic Stenosis, Supravalvular; Arteries; Biomechanical Phenomena; Compliance; Disease Models, Animal; Elastic Tissue; Elastin; Extracellular Matrix; Fibrillin-1; Fibrillins; Humans; Marfan Syndrome; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Microfilament Proteins; Phenotype

The human elastin gene (ELN) is responsible for the generation of elastic fibres in the extracellular matrix of connective tissue throughout the body, including the vocal folds. Individuals with Supravalvular aortic stenosis (SVAS) and Williams syndrome (WS) lack one normal ELN allele due to heterozygous ELN abnormalities, resulting in a haploinsufficiency. We measured perceptual and acoustic characteristics of voice quality in individuals with SVAS and WS to investigate the consequences to vocal function secondary to ELN haploinsufficiency. Results indicated that the voice quality of individuals with SVAS/WS was rated as significantly more abnormal, rough, and hoarse compared to normal controls, and that adults with SVAS/WS were rated as significantly lower in pitch. Acoustic measures indicated that individuals with SVAS/WS produced greater instability of fundamental frequency during phonation (as reflected via increased pitch sigma and increased jitter). These findings support the possibility that heterozygous ELN abnormalities negatively influence vocal fold biomechanics and the resulting sound produced by the vibrating glottis.

Topics: Adolescent; Adult; Aortic Stenosis, Supravalvular; Elastin; Female; Genetic Carrier Screening; Haplotypes; Humans; Male; Phenotype; Sound Spectrography; Speech Acoustics; Voice Disorders; Voice Quality; Williams Syndrome

Supravalvular aortic stenosis (SVAS), an inherited vascular disease, is caused by mutations in the elastin gene (ELN). Our aim was to identify novel mutations of ELN and to determine the expression of ELN in patients with SVAS. For screening mutations in ELN, we performed PCR-directed sequence analysis with genomic DNA isolated from SVAS patients and control subjects. Expression of ELN at the mRNA and protein levels were assessed by real-time PCR and Western blot analyses, respectively, using primary skin fibroblast cultures established from SVAS patients and control subjects. We identified two novel mutations of ELN, G297_A308del and Q700X, in two unrelated Korean patients with isolated SVAS. G297_A308del occurred de novo while Q700X was derived maternally. In the patient with G297_A308, elastin expression was not significantly altered at the mRNA level, but was reduced to approximately 50% of the normal control at the protein level. The elastin expression levels in the patient with Q700X were reduced to <50% of the normal controls at both the mRNA and protein levels. Our findings confirm that functional haploinsufficiency of elastin is responsible for the pathogenesis associated with isolated SVAS across different ethnic backgrounds.

Topics: Aortic Stenosis, Supravalvular; Base Sequence; Cells, Cultured; DNA Mutational Analysis; Elastin; Fibroblasts; Genetic Predisposition to Disease; Humans; Molecular Sequence Data; Mutation

Supravalvular aortic stenosis (SVAS) is a congenital heart disease that can occur as an isolated autosomal-dominant condition or as part of the developmental disorder Williams-Beuren syndrome (WBS) and is caused by heterozygous genetic lesions involving the elastin (ELN) gene locus on chromosome 7ql 1.23. SVAS is one of many phenotypic features associated with the contiguous gene microdeletion disorder, WBS, and is caused by deletion of the ELN locus on one chromosome 7 homolog. Point mutations, chromosomal deletions, and translocation involving ELN have also been described in individuals with nonsyndromic SVAS. In addition, ELN is involved in the connective tissue disorder, autosomal-dominant cutis laxa, and has been implicated as a susceptibility gene for hypertension and intracranial aneurysms. The molecular analysis of ELN defects is, therefore, an area of significant interest. Genetic screening can be achieved using a variety of techniques to detect both mutations and gross chromosome rearrangements involving the ELN locus, providing the ability to screen families and individuals with SVAS and associated elastinopathies.

Topics: Aortic Stenosis, Supravalvular; Chromatography, High Pressure Liquid; Chromosomes, Human, Pair 7; Coronary Angiography; DNA Mutational Analysis; Elastin; Exons; Genetic Linkage; Heart Defects, Congenital; Humans; Introns; Microsatellite Repeats; Nucleic Acid Denaturation; Nucleic Acid Heteroduplexes; Polymorphism, Single-Stranded Conformational

Williams-Beuren syndrome (WBS) is a neurodevelopmental microdeletion disorder that usually occurs sporadically due to its location within a highly repetitive genomic region that is unstable and prone to unequal cross-over during meiosis. The consequential loss of chromosomal material includes approximately 1.5 Mb of DNA at 7q11.23. Whilst cases of dominant inheritance have been described in the literature, there have been few reports of molecular confirmation and none have carried out detailed genotyping. We describe a Bulgarian father and son with WBS detected by fluorescent in situ hybridisation (with an elastin gene probe) and loss of heterozygosity mapping using microsatellite markers located in the critical region. These individuals appear to have a common WBS heterozygous deletion, confirming the expected dominant transmission and adding to the few familial cases reported. The deletion includes the gene FKBP6 which has recently been shown to play a role in homologous chromosome pairing in meiosis and male fertility in mouse models. Homozygous Fkbp6 -/- male mice are infertile and our data suggests that haploinsufficiency for FKBP6 does not appear to preclude male fertility in WBS, although male infertility involving this gene has the potential to follow the mouse model as a human autosomal recessive condition.

Topics: Adult; Aortic Stenosis, Supravalvular; Chromosomes, Human, Pair 7; Elastin; Facies; Fathers; Gene Deletion; Gene Dosage; Genes, Dominant; Genotype; Haplotypes; Humans; Intellectual Disability; Loss of Heterozygosity; Male; Nuclear Family; Tacrolimus Binding Proteins; Williams Syndrome

Topics: Aortic Stenosis, Supravalvular; Child; Child, Preschool; Elastin; Female; Humans; Infant; Male; Point Mutation

To elucidate the pathomechanism leading to obstructive vascular disease in patients with elastin deficiency, we compared both elastogenesis and proliferation rate of cultured aortic smooth-muscle cells (SMCs) and skin fibroblasts from five healthy control subjects, four patients with isolated supravalvular aortic stenosis (SVAS), and five patients with Williams-Beuren syndrome (WBS). Mutations were determined in each patient with SVAS and in each patient with WBS. Three mutations found in patients with SVAS were shown to result in null alleles. RNA blot hybridization, immunostaining, and metabolic labeling experiments demonstrated that SVAS cells and WBS cells have reduced elastin mRNA levels and that they consequently deposit low amounts of insoluble elastin. Although SVAS cells laid down approximately 50% of the elastin made by normal cells, WBS cells deposited only 15% of the elastin made by normal cells. The observed difference in elastin-gene expression was not caused by a difference in the stability of elastin mRNA in SVAS cells compared with WBS cells, but it did indicate that gene-interaction effects may contribute to the complex phenotype observed in patients with WBS. Abnormally low levels of elastin deposition in SVAS cells and in WBS cells were found to coincide with an increase in proliferation rate, which could be reversed by addition of exogenous insoluble elastin. We conclude that insoluble elastin is an important regulator of cellular proliferation. Thus, the reduced net deposition of insoluble elastin in arterial walls of patients with either SVAS or WBS leads to the increased proliferation of arterial SMCs. This results in the formation of multilayer thickening of the tunica media of large arteries and, consequently, in the development of hyperplastic intimal lesions leading to segmental arterial occlusion.

Topics: Adolescent; Adult; Aortic Stenosis, Supravalvular; Base Sequence; Case-Control Studies; Cell Division; Cells, Cultured; Child; Child, Preschool; DNA Mutational Analysis; DNA, Complementary; Elastin; Female; Fibroblasts; Humans; Infant; Male; Middle Aged; Muscle, Smooth, Vascular; RNA, Messenger; Solubility; Williams Syndrome

Topics: Adult; Aortic Stenosis, Supravalvular; Cytosine; Elastin; Exons; Female; Frameshift Mutation; Humans; Male; Mutation; Myocardial Infarction; Nuclear Family; Point Mutation; Sequence Deletion

We have identified two elastin gene (ELN) mutations located in cis in two related families with supravalvular aortic stenosis (SVAS). These mutations included an in-frame duplication in exon 18 (1034-1057dup) and a single base substitution in exon 26 (1829G-->A) predicted to result in the amino acid substitution R610Q. Haplotype analysis in one of the families identified an individual with a recombination between exon 18 and 26 of the elastin gene. This individual was unaffected and carried the exon 18 insertion mutation but not 1829G-->A. Skin fibroblasts were established from this recombinant normal individual and from an affected individual carrying both of the mutations. Reverse transcription/polymerase chain reaction (RT-PCR) analysis indicated that the expression of the mutant allele was reduced to 12%-27% of the normal allele in the affected but not in the unaffected individual. RNA-blot hybridization and immunoprecipitation experiments revealed reduced steady-state elastin mRNA levels and tropoelastin synthesis in the affected individual. RT-PCR analysis of the mRNA rescued by cycloheximide treatment indicated that mutation 1829G-->A created a cryptic donor splice site within exon 26, resulting in the deletion of four nucleotides at the 3'-end of exon 26 and a frameshift in the mRNA. This frameshift mutation generated a premature termination codon in the domain encoded by exon 28, clearly resulting in nonsense-mediated decay (NMD) of this frameshift RNA product. Despite considerable variability in the molecular nature of mutations responsible for SVAS, the unifying mechanism appears to be the generation of null alleles by NMD leading to elastin haploinsufficiency.

Topics: Alleles; Amino Acid Sequence; Aortic Stenosis, Supravalvular; Base Sequence; DNA; DNA Primers; Elastin; Exons; Female; Gene Frequency; Humans; Male; Molecular Sequence Data; Mutation, Missense; Pedigree; Reverse Transcriptase Polymerase Chain Reaction

Supravalvular aortic stenosis (SVAS) is a congenital narrowing of the ascending aorta which can occur sporadically, as an autosomal dominant condition, or as one component of Williams syndrome. SVAS is caused by translocations, gross deletions and point mutations that disrupt the elastin gene (ELN) on 7q11.23. Functional hemizygosity for elastin is known to be the cause of SVAS in patients with gross chromosomal abnormalities involving ELN. However, the pathogenic mechanisms of point mutations are less clear. One hundred patients with diagnosed SVAS and normal karyotypes were screened for mutations in the elastin gene to further elucidate the molecular pathology of the disorder. Mutations associated with the vascular disease were detected in 35 patients, and included nonsense, frameshift, translation initiation and splice site mutations. The four missense mutations identified are the first of this type to be associated with SVAS. Here we describe the spectrum of mutations occurring in familial and sporadic SVAS and attempt to define the mutational mechanisms involved in SVAS. SVAS shows variable penetrance within families but the progressive nature of the disorder in some cases, makes identification of the molecular lesions important for future preventative treatments.

Topics: Alternative Splicing; Aortic Stenosis, Supravalvular; Codon, Initiator; Codon, Nonsense; DNA; Elastin; Female; Humans; Male; Mutation, Missense; Pedigree; Polymorphism, Genetic