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INTRODUCTION: The MYH7 c.5135Gâ¯> A p.(Arg1712Gln) variant has been identified in several patients worldwide and is classified as pathogenic in the ClinVar database. We aimed to delineate its associated phenotype and evaluate a potential founder effect. METHODS: We retrospectively collected clinical and genetic data of 22 probands and 74 family members from an international cohort. RESULTS: In total, 53 individuals carried the MYH7 p.(Arg1712Gln) variant, of whom 38 (72%) were diagnosed with hypertrophic cardiomyopathy (HCM). Mean age at HCM diagnosis was 48.8 years (standard deviation: 18.1; range: 8-74). The clinical presentation ranged from asymptomatic HCM to arrhythmias (atrial fibrillation and malignant ventricular arrhythmias). Aborted sudden cardiac death (SCD) leading to the diagnosis of HCM occurred in one proband at the age of 68 years, and a family history of SCD was reported by 39% (5/13) probands. Neither heart failure deaths nor heart transplants were reported. Women had a generally later-onset disease, with 14% of female carriers diagnosed with HCM at age 50 years compared with 54% of male carriers. In both sexes, the disease was fully penetrant by age 75 years. Haplotypes were reconstructed for 35 patients and showed a founder effect in a subset of patients. CONCLUSION: MYH7 p.(Arg1712Gln) is a pathogenic founder variant with a consistent HCM phenotype that may present with delayed penetrance. This suggested that clinical follow-up should be pursued after the seventh decade in healthy carriers and that longer intervals between screening may be justified in healthy women <â¯30 years.
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OBJECTIVES: To investigate the presence of hypertrophic cardiomyopathy (HCM) at first cardiac evaluation and during follow-up and cardiac events in predictively tested children who are mutation positive. STUDY DESIGN: The study included 119 predictively tested children who were mutation positive, with a mean age of 12.1 years. A family history and clinical variables from all cardiac evaluations after predictive genetic testing were recorded. Outcome measures were a clinical diagnosis of HCM, death, and cardiac events. RESULTS: No child died during a mean follow-up of 6.9 ± 3.8 years: 95 children were evaluated more than once. Eight (6.7%) children who were mutation positive were diagnosed with HCM at one or more cardiac evaluation(s), some with severe hypertrophy. In one patient who fulfilled the diagnostic criteria for HCM a cardiac event occurred during follow-up. She received an appropriate implantable cardioverter-defibrillator shock 4 years after a prophylactic implantable cardioverter-defibrillator was implanted. CONCLUSION: The risk for predictively tested children who are mutation positive to develop HCM during childhood and the risk of cardiac events in children who are phenotype negative are low. In children who are phenotype positive, however, severe hypertrophy and cardiac events can develop. Further research is necessary to study whether the interval between cardiac evaluations in children can be increased after a normal first evaluation and whether risk stratification for sudden cardiac death is necessary in children who are phenotype negative.
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Cardiomiopatía Hipertrófica/genética , Penetrancia , Adolescente , Cardiomiopatía Hipertrófica/epidemiología , Cardiomiopatía Hipertrófica/mortalidad , Niño , Desfibriladores Implantables , Femenino , Estudios de Seguimiento , Predisposición Genética a la Enfermedad , Pruebas Genéticas , Humanos , Masculino , Mutación , FenotipoRESUMEN
BACKGROUND: MYH7 variants cause hypertrophic cardiomyopathy (HCM), noncompaction cardiomyopathy (NCCM), and dilated cardiomyopathy (DCM). Screening of relatives of patients with genetic cardiomyopathy is recommended from 10 to 12 years of age onward, irrespective of the affected gene. OBJECTIVES: This study sought to study the penetrance and prognosis of MYH7 variant-associated cardiomyopathies. METHODS: In this multicenter cohort study, penetrance and major cardiomyopathy-related events (MCEs) were assessed in carriers of (likely) pathogenic MYH7 variants by using Kaplan-Meier curves and log-rank tests. Prognostic factors were evaluated using Cox regression with time-dependent coefficients. RESULTS: In total, 581 subjects (30.1% index patients, 48.4% male, median age 37.0 years [IQR: 19.5-50.2 years]) were included. HCM was diagnosed in 226 subjects, NCCM in 70, and DCM in 55. Early penetrance and MCEs (age <12 years) were common among NCCM-associated variant carriers (21.2% and 12.0%, respectively) and DCM-associated variant carriers (15.3% and 10.0%, respectively), compared with HCM-associated variant carriers (2.9% and 2.1%, respectively). Penetrance was significantly increased in carriers of converter region variants (adjusted HR: 1.87; 95% CI: 1.15-3.04; P = 0.012) and at age ≤1 year in NCCM-associated or DCM-associated variant carriers (adjusted HR: 21.17; 95% CI: 4.81-93.20; P < 0.001) and subjects with a family history of early MCEs (adjusted HR: 2.45; 95% CI: 1.09-5.50; P = 0.030). The risk of MCE was increased in subjects with a family history of early MCEs (adjusted HR: 1.82; 95% CI: 1.15-2.87; P = 0.010) and at age ≤5 years in NCCM-associated or DCM-associated variant carriers (adjusted HR: 38.82; 95% CI: 5.16-291.88; P < 0.001). CONCLUSIONS: MYH7 variants can cause cardiomyopathies and MCEs at a young age. Screening at younger ages may be warranted, particularly in carriers of NCCM- or DCM-associated variants and/or with a family history of MCEs at <12 years.
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Cardiomiopatías , Cardiomiopatía Dilatada , Cardiomiopatía Hipertrófica , Insuficiencia Cardíaca , Humanos , Masculino , Adulto , Preescolar , Niño , Femenino , Penetrancia , Estudios de Cohortes , Cardiomiopatías/genética , Cardiomiopatía Dilatada/genética , Pronóstico , Mutación , Cadenas Pesadas de Miosina/genética , Miosinas Cardíacas/genéticaRESUMEN
POPDC2 encodes for the Popeye domain-containing protein 2 which has an important role in cardiac pacemaking and conduction, due in part to its cAMP-dependent binding and regulation of TREK-1 potassium channels. Loss of Popdc2 in mice results in sinus pauses and bradycardia and morpholino knockdown of popdc2 in zebrafish results in atrioventricular (AV) block. We identified bi-allelic variants in POPDC2 in 4 families that presented with a phenotypic spectrum consisting of sinus node dysfunction, AV conduction defects and hypertrophic cardiomyopathy. Using homology modelling we show that the identified POPDC2 variants are predicted to diminish the ability of POPDC2 to bind cAMP. In in vitro electrophysiological studies we demonstrated that, while co-expression of wild-type POPDC2 with TREK-1 increased TREK-1 current density, POPDC2 variants found in the patients failed to increase TREK-1 current density. While patient muscle biopsy did not show clear myopathic disease, it showed significant reduction of the expression of both POPDC1 and POPDC2, suggesting that stability and/or membrane trafficking of the POPDC1-POPDC2 complex is impaired by pathogenic variants in any of the two proteins. Single-cell RNA sequencing from human hearts demonstrated that co-expression of POPDC1 and 2 was most prevalent in AV node, AV node pacemaker and AV bundle cells. Sinoatrial node cells expressed POPDC2 abundantly, but expression of POPDC1 was sparse. Together, these results concur with predisposition to AV node disease in humans with loss-of-function variants in POPDC1 and POPDC2 and presence of sinus node disease in POPDC2, but not in POPDC1 related disease in human. Using population-level genetic data of more than 1 million individuals we showed that none of the familial variants were associated with clinical outcomes in heterozygous state, suggesting that heterozygous family members are unlikely to develop clinical manifestations and therefore might not necessitate clinical follow-up. Our findings provide evidence for POPDC2 as the cause of a novel Mendelian autosomal recessive cardiac syndrome, consistent with previous work showing that mice and zebrafish deficient in functional POPDC2 display sinus and AV node dysfunction.
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Left ventricular noncompaction (LVNC) is a relatively common genetic cardiomyopathy, characterized by prominent trabeculations with deep intertrabecular recesses in mainly the left ventricle. Although LVNC often occurs in an isolated entity, it may also be present in various types of congenital heart disease (CHD). The most prevalent CHD in LVNC is Ebstein anomaly, which is a rare form of CHD characterized by apical displacement and partial fusion of the septal and posterior leaflet of the tricuspid valve with the ventricular septum. Several reports of sporadic as well as familial cases of Ebstein anomaly associated with LVNC have been reported. Recent studies identified mutations in the MYH7 gene, encoding the sarcomeric ß-myosin heavy chain protein, in patients harboring this specific phenotype. Here, we will review the association between Ebstein anomaly, LVNC and mutations in MYH7, which seems to represent a subtype of Ebstein anomaly with autosomal dominant inheritance and variable penetrance.
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Miosinas Cardíacas/genética , Anomalía de Ebstein/genética , Ventrículos Cardíacos/anomalías , No Compactación Aislada del Miocardio Ventricular/genética , Cadenas Pesadas de Miosina/genética , Anomalía de Ebstein/complicaciones , Genes Dominantes , Humanos , No Compactación Aislada del Miocardio Ventricular/complicaciones , Mutación , FenotipoRESUMEN
BACKGROUND: Genetic variants in TNNI3K (troponin-I interacting kinase) have previously been associated with dilated cardiomyopathy (DCM), cardiac conduction disease, and supraventricular tachycardias. However, the link between TNNI3K variants and these cardiac phenotypes shows a lack of consensus concerning phenotype and protein function. METHODS: We describe a systematic retrospective study of a cohort of patients undergoing genetic testing for cardiac arrhythmias and cardiomyopathy including TNNI3K. We further performed burden testing of TNNI3K in the UK Biobank. For 2 novel TNNI3K variants, we tested cosegregation. TNNI3K kinase function was estimated by TNNI3K autophosphorylation assays. RESULTS: We demonstrate enrichment of rare coding TNNI3K variants in DCM patients in the Amsterdam cohort. In the UK Biobank, we observed an association between TNNI3K missense (but not loss-of-function) variants and DCM and atrial fibrillation. Furthermore, we demonstrate genetic segregation for 2 rare variants, TNNI3K-p.Ile512Thr and TNNI3K-p.His592Tyr, with phenotypes consisting of DCM, cardiac conduction disease, and supraventricular tachycardia, together with increased autophosphorylation. In contrast, TNNI3K-p.Arg556_Asn590del, a likely benign variant, demonstrated depleted autophosphorylation. CONCLUSIONS: Our findings demonstrate an increased burden of rare coding TNNI3K variants in cardiac patients with DCM. Furthermore, we present 2 novel likely pathogenic TNNI3K variants with increased autophosphorylation, suggesting that enhanced autophosphorylation is likely to drive pathogenicity.
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Cardiomiopatía Dilatada , Humanos , Cardiomiopatía Dilatada/diagnóstico , Cardiomiopatía Dilatada/genética , Estudios Retrospectivos , Arritmias Cardíacas/genética , Pruebas Genéticas , Trastorno del Sistema de Conducción Cardíaco/genética , Proteínas Serina-Treonina Quinasas/genéticaRESUMEN
The heart muscle diseases hypertrophic (HCM) and dilated (DCM) cardiomyopathies are leading causes of sudden death and heart failure in young, otherwise healthy, individuals. We conducted genome-wide association studies and multi-trait analyses in HCM (1,733 cases), DCM (5,521 cases) and nine left ventricular (LV) traits (19,260 UK Biobank participants with structurally normal hearts). We identified 16 loci associated with HCM, 13 with DCM and 23 with LV traits. We show strong genetic correlations between LV traits and cardiomyopathies, with opposing effects in HCM and DCM. Two-sample Mendelian randomization supports a causal association linking increased LV contractility with HCM risk. A polygenic risk score explains a significant portion of phenotypic variability in carriers of HCM-causing rare variants. Our findings thus provide evidence that polygenic risk score may account for variability in Mendelian diseases. More broadly, we provide insights into how genetic pathways may lead to distinct disorders through opposing genetic effects.
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Cardiomiopatía Dilatada/genética , Cardiomiopatía Hipertrófica/genética , Cardiomiopatía Dilatada/mortalidad , Cardiomiopatía Dilatada/fisiopatología , Cardiomiopatía Hipertrófica/mortalidad , Cardiomiopatía Hipertrófica/fisiopatología , Estudios de Casos y Controles , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Ventrículos Cardíacos/fisiopatología , Humanos , Estimación de Kaplan-Meier , Desequilibrio de Ligamiento , Polimorfismo de Nucleótido Simple , Sitios de Carácter Cuantitativo , Función Ventricular Izquierda/genéticaRESUMEN
OBJECTIVES: Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disorder that affects over one in 500 persons worldwide. The autosomal dominant transmission of HCM implies that many relatives are at risk for HCM associated morbidity and mortality, therefore genetic testing and counselling is of great importance. However, in only 50-60% of the patients a mutation is found, which hampers predictive genetic testing in relatives. In HCM patients in whom the causal mutation has not been identified (yet), phenocopies of HCM - i.e. diseases that mimic HCM - could be responsible for the HCM phenotype. One of the HCM phenocopies is transthyretin amyloidosis (ATTR), caused by mutations in the transthyretin (TTR) gene. METHODS: From 697 HCM index patients referred to our cardiogenetics outpatient clinic and tested for HCM associated genes between January 1997 and December 2012, we selected the ones without a detected causal mutation (n = 345). In these patients, additional DNA analysis of the TTR gene was performed. RESULTS: In four patients (1.2%), a TTR mutation was detected (E7G, V30M, T119M, V122I). The E7G mutation is probably a non-pathogenic mutation. The T119M mutation is a known TTR mutation, but does not cause a cardiac phenotype. So in two (0.6%) patients, TTR analysis identified the cause of their HCM. CONCLUSIONS: ATTR should always be considered in patients with unexplained HCM, especially because of the great benefit of an early diagnosis regarding treatment and prognosis.
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Neuropatías Amiloides Familiares/genética , Cardiomiopatía Hipertrófica/genética , Mutación Missense , Prealbúmina/genética , Anciano , Anciano de 80 o más Años , Sustitución de Aminoácidos , Neuropatías Amiloides Familiares/metabolismo , Neuropatías Amiloides Familiares/patología , Cardiomiopatía Hipertrófica/metabolismo , Cardiomiopatía Hipertrófica/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Prealbúmina/metabolismoRESUMEN
AIMS: Disease mechanisms regarding hypertrophic cardiomyopathy (HCM) are largely unknown and disease onset varies. Sarcomere mutations might induce energy depletion for which until now there is no direct evidence at sarcomere level in human HCM. This study investigated if mutations in genes encoding myosin-binding protein C (MYBPC3) and myosin heavy chain (MYH7) underlie changes in the energetic cost of contraction in the development of human HCM disease. METHODS AND RESULTS: Energetic cost of contraction was studied in vitro by measurements of force development and ATPase activity in cardiac muscle strips from 26 manifest HCM patients (11 MYBPC3mut, 9 MYH7mut, and 6 sarcomere mutation-negative, HCMsmn). In addition, in vivo, the ratio between external work (EW) and myocardial oxygen consumption (MVO2) to obtain myocardial external efficiency (MEE) was determined in 28 pre-hypertrophic mutation carriers (14 MYBPC3mut and 14 MYH7mut) and 14 healthy controls using [(11)C]-acetate positron emission tomography and cardiovascular magnetic resonance imaging. Tension cost (TC), i.e. ATPase activity during force development, was higher in MYBPC3mut and MYH7mut compared with HCMsmn at saturating [Ca(2+)]. TC was also significantly higher in MYH7mut at submaximal, more physiological [Ca(2+)]. EW was significantly lower in both mutation carrier groups, while MVO2 did not differ. MEE was significantly lower in both mutation carrier groups compared with controls, showing the lowest efficiency in MYH7 mutation carriers. CONCLUSION: We provide direct evidence that sarcomere mutations perturb the energetic cost of cardiac contraction. Gene-specific severity of cardiac abnormalities may underlie differences in disease onset and suggests that early initiation of metabolic treatment may be beneficial, in particular, in MYH7 mutation carriers.
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Miosinas Cardíacas/genética , Cardiomiopatía Hipertrófica/genética , Proteínas Portadoras/genética , Mutación/genética , Contracción Miocárdica/genética , Cadenas Pesadas de Miosina/genética , Citoesqueleto de Actina/genética , Adulto , Anciano , Miosinas Cardíacas/metabolismo , Femenino , Regulación de la Expresión Génica , Genotipo , Humanos , Masculino , Persona de Mediana Edad , Contracción Miocárdica/fisiología , Sarcómeros/genética , Sarcómeros/patologíaRESUMEN
BACKGROUND: Familial forms of primary sinus bradycardia have sometimes been attributed to mutations in HCN4, SCN5A, and ANK2. In these studies, no structural cardiac alterations were reported in mutation carriers. However, a cluster of reports in the literature describe patients presenting with sinus bradycardia in association with left ventricular noncompaction cardiomyopathy (LVNC), pointing to a shared genetic cause. OBJECTIVES: This study sought to identify the genetic defect underlying the combined clinical presentation of bradycardia and LVNC, hypothesizing that these 2 clinical abnormalities have a common genetic cause. METHODS: Exome sequencing was carried out in 2 cousins from the index family that were affected by the combined bradycardia-LVNC phenotype; shared variants thus identified were subsequently overlaid with the chromosomal regions shared among 5 affected family members that were identified using single nucleotide polymorphism array analysis. RESULTS: The combined linkage analysis and exome sequencing in the index family identified 11 novel variants shared among the 2 affected cousins. One of these, p.Gly482Arg in HCN4, segregated with the combined bradycardia and LVNC phenotype in the entire family. Subsequent screening of HCN4 in 3 additional families with the same clinical combination of bradycardia and LVNC identified HCN4 mutations in each. In electrophysiological studies, all found HCN4 mutations showed a more negative voltage dependence of activation, consistent with the observed bradycardia. CONCLUSIONS: Although mutations in HCN4 have been previously linked to bradycardia, our study provides the first evidence to our knowledge that mutations in this ion channel gene also may be associated with structural abnormalities of the myocardium.