Thoracic aortic aneurysms and dissections are a main feature of connective tissue disorders, such as Marfan syndrome and Loeys-Dietz syndrome. We delineated a new syndrome presenting with aneurysms, ...dissections and tortuosity throughout the arterial tree in association with mild craniofacial features and skeletal and cutaneous anomalies. In contrast with other aneurysm syndromes, most of these affected individuals presented with early-onset osteoarthritis. We mapped the genetic locus to chromosome 15q22.2-24.2 and show that the disease is caused by mutations in SMAD3. This gene encodes a member of the TGF-β pathway that is essential for TGF-β signal transmission. SMAD3 mutations lead to increased aortic expression of several key players in the TGF-β pathway, including SMAD3. Molecular diagnosis will allow early and reliable identification of cases and relatives at risk for major cardiovascular complications. Our findings endorse the TGF-β pathway as the primary pharmacological target for the development of new treatments for aortic aneurysms and osteoarthritis.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Aneurysms-osteoarthritis syndrome (AOS) is a new autosomal dominant syndromic form of thoracic aortic aneurysms and dissections characterised by the presence of arterial aneurysms and tortuosity, ...mild craniofacial, skeletal and cutaneous anomalies, and early-onset osteoarthritis. AOS is caused by mutations in the SMAD3 gene.
A cohort of 393 patients with aneurysms without mutation in FBN1, TGFBR1 and TGFBR2 was screened for mutations in SMAD3. The patients originated from The Netherlands, Belgium, Switzerland and USA. The clinical phenotype in a total of 45 patients from eight different AOS families with eight different SMAD3 mutations is described. In all patients with a SMAD3 mutation, clinical records were reviewed and extensive genetic, cardiovascular and orthopaedic examinations were performed.
Five novel SMAD3 mutations (one nonsense, two missense and two frame-shift mutations) were identified in five new AOS families. A follow-up description of the three families with a SMAD3 mutation previously described by the authors was included. In the majority of patients, early-onset joint abnormalities, including osteoarthritis and osteochondritis dissecans, were the initial symptom for which medical advice was sought. Cardiovascular abnormalities were present in almost 90% of patients, and involved mainly aortic aneurysms and dissections. Aneurysms and tortuosity were found in the aorta and other arteries throughout the body, including intracranial arteries. Of the patients who first presented with joint abnormalities, 20% died suddenly from aortic dissection. The presence of mild craniofacial abnormalities including hypertelorism and abnormal uvula may aid the recognition of this syndrome.
The authors provide further insight into the phenotype of AOS with SMAD3 mutations, and present recommendations for a clinical work-up.
Contemporary hypertrophic cardiomyopathy (HCM) family screening includes clinical evaluation and genetic testing (GT). This screening strategy requires the identification of a pathogenic mutation in ...the proband. Our aim was to examine the results of this HCM screening strategy.
Between 1985 and 2016, 777 relatives of 209 probands were assessed in the context of HCM screening. Genotype-positive (G+) relatives and relatives without genetic testing (GT) underwent repeated clinical evaluations. In genotype-negative (G-) relatives mortality was assessed during follow-up.
A pathogenic mutation was identified in 72% of probands. After counseling, GT was performed in 620 (80%) relatives: 264 (43%) were G+ (age 41±18 y) and 356 (57%) were G- (age 48±17 y). At first screening, HCM was diagnosed in 98 (37%) G+ relatives and 28 (17%) relatives without GT (
<0.001). During 9 years follow-up of relatives diagnosed with HCM, 8 (6%) underwent septal reduction therapy, 16 (16%) received primary prevention ICDs, and cardiac mortality was 0.3%/year. During 7 years follow-up of relatives without HCM, 29 (16%) developed HCM. Survival at 5/10 years was 99%/95% in G+ relatives, 97%/94% in G- relatives (
=0.8), and 100%/100% in relatives without GT.
HCM was identified in 30% of relatives at first screening, and 16% developed HCM during 7 years of repeated evaluation. GT led to a discharge from clinical follow-up in 46% of the study population. Survival in the relatives was good.
BACKGROUND—Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome associated with mutations in the cardiac ryanodine receptor gene (Ryr2) in the majority of ...patients. Previous studies of CPVT patients mainly involved probands, so current insight into disease penetrance, expression, genotype-phenotype correlations, and arrhythmic event rates in relatives carrying the Ryr2 mutation is limited.
METHODS AND RESULTS—One-hundred sixteen relatives carrying the Ryr2 mutation from 15 families who were identified by cascade screening of the Ryr2 mutation causing CPVT in the proband were clinically characterized, including 61 relatives from 1 family. Fifty-four of 108 antiarrhythmic drug-free relatives (50%) had a CPVT phenotype at the first cardiological examination, including 27 (25%) with nonsustained ventricular tachycardia. Relatives carrying a Ryr2 mutation in the C-terminal channel-forming domain showed an increased odds of nonsustained ventricular tachycardia (odds ratio, 4.1; 95% CI, 1.5–11.5; P=0.007, compared with N-terminal domain) compared with N-terminal domain. Sinus bradycardia was observed in 19% of relatives, whereas other supraventricular dysrhythmias were present in 16%. Ninety-eight (most actively treated) relatives (84%) were followed up for a median of 4.7 years (range, 0.3–19.0 years). During follow-up, 2 asymptomatic relatives experienced exercise-induced syncope. One relative was not being treated, whereas the other was noncompliant. None of the 116 relatives died of CPVT during a 6.7-year follow-up (range, 1.4–20.9 years).
CONCLUSIONS—Relatives carrying an Ryr2 mutation show a marked phenotypic diversity. The vast majority do not have signs of supraventricular disease manifestations. Mutation location may be associated with severity of the phenotype. The arrhythmic event rate during follow-up was low.
Objectives The purpose of this study was describe the cardiovascular phenotype of the aneurysms-osteoarthritis syndrome (AOS) and to provide clinical recommendations. Background AOS, caused by ...pathogenic SMAD3 variants, is a recently described autosomal dominant syndrome characterized by aneurysms and arterial tortuosity in combination with osteoarthritis. Methods AOS patients in participating centers underwent extensive cardiovascular evaluation, including imaging, arterial stiffness measurements, and biochemical studies. Results We included 44 AOS patients from 7 families with pathogenic SMAD3 variants (mean age: 42 ± 17 years). In 71%, an aortic root aneurysm was found. In 33%, aneurysms in other arteries in the thorax and abdomen were diagnosed, and in 48%, arterial tortuosity was diagnosed. In 16 patients, cerebrovascular imaging was performed, and cerebrovascular abnormalities were detected in 56% of them. Fifteen deaths occurred at a mean age of 54 ± 15 years. The main cause of death was aortic dissection (9 of 15; 60%), which occurred at mildly increased aortic diameters (range: 40 to 63 mm). Furthermore, cardiac abnormalities were diagnosed, such as congenital heart defects (6%), mitral valve abnormalities (51%), left ventricular hypertrophy (19%), and atrial fibrillation (22%). N-terminal brain natriuretic peptide (NT-proBNP) was significantly higher in AOS patients compared with matched controls (p < 0.001). Aortic pulse wave velocity was high-normal (9.2 ± 2.2 m/s), indicating increased aortic stiffness, which strongly correlated with NT-proBNP (r = 0.731, p = 0.005). Conclusions AOS predisposes patients to aggressive and widespread cardiovascular disease and is associated with high mortality. Dissections can occur at relatively mildly increased aortic diameters; therefore, early elective repair of the ascending aorta should be considered. Moreover, cerebrovascular abnormalities were encountered in most patients.
RATIONALE:Congenital heart malformations are a major cause of morbidity and mortality, especially in young children. Failure to establish normal left-right (L-R) asymmetry often results in ...cardiovascular malformations and other laterality defects of visceral organs.
OBJECTIVE:To identify genetic mutations causing cardiac laterality defects.
METHODS AND RESULTS:We performed a genome-wide linkage analysis in patients with cardiac laterality defects from a consanguineous family. The patients had combinations of defects that included dextrocardia, transposition of great arteries, double-outlet right ventricle, atrioventricular septal defects, and caval vein abnormalities. Sequencing of positional candidate genes identified mutations in NPHP4. We performed mutation analysis of NPHP4 in 146 unrelated patients with similar cardiac laterality defects. Forty-one percent of these patients also had laterality defects of the abdominal organs. We identified 8 additional missense variants that were absent or very rare in control subjects. To study the role of nphp4 in establishing L-R asymmetry, we used antisense morpholinos to knockdown nphp4 expression in zebrafish. Depletion of nphp4 disrupted L-R patterning as well as cardiac and gut laterality. Cardiac laterality defects were partially rescued by human NPHP4 mRNA, whereas mutant NPHP4 containing genetic variants found in patients failed to rescue. We show that nphp4 is involved in the formation of motile cilia in Kupfferʼs vesicle, which generate asymmetrical fluid flow necessary for normal L-R asymmetry.
CONCLUSIONS:NPHP4 mutations are associated with cardiac laterality defects and heterotaxy. In zebrafish, nphp4 is essential for the development and function of Kupfferʼs vesicle cilia and is required for global L-R patterning.
(Myosin-binding protein C) founder mutations account for 35% of hypertrophic cardiomyopathy (HCM) cases in the Netherlands. We compared clinical characteristics and outcome of
founder mutation (FG+) ...HCM with nonfounder genotype-positive (G+) and genotype-negative (G-) HCM.
The study included 680 subjects: 271 FG+ carriers, 132 G+ probands with HCM, and 277 G- probands with HCM. FG+ carriers included 134 FG+ probands with HCM, 54 FG+ relatives diagnosed with HCM after family screening, 74 FG+/phenotype-negative relatives, and 9 with noncompaction or dilated cardiomyopathy. The clinical phenotype of FG+ and G+ probands with HCM was similar. FG+ and G+ probands were younger with less left ventricular outflow tract obstruction than G- probands, however, had more hypertrophy, and nonsustained ventricular tachycardia. FG+ relatives with HCM had less hypertrophy, smaller left atria, and less systolic and diastolic dysfunction than FG+ probands with HCM. After 8±6 years, cardiovascular mortality in FG+ probands with HCM was similar to G+ HCM (22% versus 14%; log-rank
=0.14), but higher than G- HCM (22% versus 6%; log-rank
<0.001) and FG+ relatives with HCM (22% versus 4%;
=0.009). Cardiac events were absent in FG+/phenotype-negative relatives; subtle HCM developed in 11% during 6 years of follow-up.
Clinical phenotype and outcome of FG+ HCM was similar to G+ HCM but worse than G- HCM and FG+ HCM diagnosed in the context of family screening. These findings indicate the need for more intensive follow-up of FG+ and G+ HCM versus G- HCM and FG+ HCM in relatives.
Abstract Background Cardiomyopathies are usually inherited and predominantly affect adults, but they can also present in childhood. Although our understanding of the molecular basis of pediatric ...cardiomyopathy has improved, the underlying mechanism remains elusive in a substantial proportion of cases. Objectives This study aimed to identify new genes involved in pediatric cardiomyopathy. Methods The authors performed homozygosity mapping and whole-exome sequencing in 2 consanguineous families with idiopathic pediatric cardiomyopathy. Sixty unrelated patients with pediatric cardiomyopathy were subsequently screened for mutations in a candidate gene. First-degree relatives were submitted to cardiac screening and cascade genetic testing. Myocardial samples from 2 patients were processed for histological and immunohistochemical studies. Results We identified 5 patients from 3 unrelated families with pediatric cardiomyopathy caused by homozygous truncating mutations in ALPK3 , a gene encoding a nuclear kinase that plays an essential role in early differentiation of cardiomyocytes. All patients with biallelic mutations presented with severe hypertrophic and/or dilated cardiomyopathy in utero, at birth, or in early childhood. Three patients died from heart failure within the first week of life. Moreover, 2 of 10 (20%) heterozygous family members showed hypertrophic cardiomyopathy with an atypical distribution of hypertrophy. Deficiency of alpha-kinase 3 has previously been associated with features of both hypertrophic and dilated cardiomyopathy in mice. Consistent with studies in knockout mice, we provide microscopic evidence for intercalated disc remodeling. Conclusions Biallelic truncating mutations in the newly identified gene ALPK3 give rise to severe, early-onset cardiomyopathy in humans. Our findings highlight the importance of transcription factor pathways in the molecular mechanisms underlying human cardiomyopathies.
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