Familial Restrictive Cardiomyopathy Research Articles

Titin: The Missing Link in Cardiac Physiology

Titin, an extraordinary protein known for its colossal size and multifaceted roles, is a cornerstone in the structural and functional dynamics of striated muscle tissues, including the heart and skeletal muscles. Its sheer enormity, with a molecular weight exceeding 3000 kDa, is paralleled only by the immense influence it exerts on muscle physiology. This review will delve into the remarkable structural organization of Titin and the genetics of this molecule, including the common mutations resulting in various cardiomyopathies. We will delve deeper into its role in dilated cardiomyopathy, familial restrictive cardiomyopathy, hypertrophic cardiomyopathy, and left ventricular noncompaction cardiomyopathy. This review culminates by discussing the prospects of therapeutic strategies targeting Titin. While these interventions remain primarily theoretical, the possibilities are intriguing. Patients with Titin truncation mutations present unique challenges, but innovative approaches like gene therapy or preemptive treatments with drugs such as angiotensin-converting enzyme inhibitors or beta-blockers offer hope. This multi-pronged approach highlights the significance of understanding Titin’s multifaceted role and its potential as a target for future therapeutic interventions.

Co-segregation of variant NSUN2 Lue198Arg among Iranian family with intellectual disability: a case report

BackgroundIntellectual disability is characterized by impairments in adaptive behavior and cognitive functioning manifested during the developmental period. Since disabilities are heterogeneous, variant analysis can help us confirm and accurately diagnose children with intellectual disabilities. Some papers reported that bi-allelic variants of the NSUN2 gene caused a group of neurological disorders, including non-syndromic autosomal recessive intellectual disability (NS-ARID), Dubowitz syndrome, and familial restrictive cardiomyopathy 1 (RCM1). We report on a consanguineous family with three siblings diagnosed with intellectual disability.Case presentationThe 7-year-old female was referred to Ali-Asghar hospital, Zahedan, Iran, with clinical manifestations comprising moderate intellectual disability, ptosis, long face, and short stature. Chromosome banding, metabolic testing, and magnetic resonance imaging examinations revealed no abnormalities. Accordingly, other affected siblings born of the same parents were considered. Whole-exome sequencing (WES) was conducted on the sufferer to consider NS-ARID variants. Findings identified a variant with uncertain significance (NM_017755.6: c.593 T > G) in the NSUN2 gene in the proband. This variant was confirmed through Sanger sequencing of the affected and unaffected family members. Besides, the computational results showed that the L198R exchange could change the interaction between wild-type and other residues in the protein. The affected patients with NS-ARID had similar clinical characteristics and genetic abnormalities.ConclusionTaken together, we described the variant in three Iranian siblings; further expanding of the other variants involved in the disease will be evident by using high-throughput sequencing technologies.

Restrictive cardiomyopathy: from genetics and clinical overview to animal modeling.

Restrictive cardiomyopathy (RCM), a potentially devastating heart muscle disorder, is characterized by diastolic dysfunction due to abnormal muscle relaxation and myocardial stiffness resulting in restrictive filling of the ventricles. Diastolic dysfunction is often accompanied by left atrial or bi-atrial enlargement and normal ventricular size and systolic function. RCM is the rarest form of cardiomyopathy, accounting for 2-5% of pediatric cardiomyopathy cases, however, survival rates have been reported to be 82%, 80%, and 68% at 1-, 2-, and 5-years after diagnosis, respectively. RCM can be idiopathic, familial, or secondary to a systemic disorder, such as amyloidosis, sarcoidosis, and hereditary hemochromatosis. Approximately 30% of cases are familial RCM, and the genes that have been linked to RCM are cTnT, cTnI, MyBP-C, MYH7, MYL2, MYL3, DES, MYPN, TTN, BAG3, DCBLD2, LNMA, and FLNC. Increased Ca2+ sensitivity, sarcomere disruption, and protein aggregates are some of the few mechanisms of pathogenesis that have been revealed by studies utilizing cell lines and animal models. Additional exploration into the pathogenesis of RCM is necessary to create novel therapeutic strategies to reverse restrictive cardiomyopathic phenotypes.

A CASE OF RARE INHERITED RESTRICTIVE CARDIOMYOPATHY CAUSED BY A NOVEL MUTATION IN MYH7 GENE

Introduction: Inherited restrictive cardiomyopathy (RCM) is a rare cause of RCM associated with cytoskeletal and sarcoma gene mutations. We describe a case of inherited RCM due to MYH7s genetic mutation.Case description: A 66 year-old-woman was admitted for acute global heart failure. She had a family history of RCM with a mutation of MYH7 gene: sons sudden death at 30, one of her daughters who is 40 and grandson who is 1. The transthoracic cardiac ultrasound (TTE) showed a bi-atrial dilation, a non-dilated left ventricle (LV) non-hypertrophied. Genetic investigation found the same pathogenic missense mutation (c. 1477A>G in heterozygous state) in our patient and her daughter who has a non-obstructive hypertrophy cardiomyopathy (HCM).A few weeks later, our patient had a syncope on complete atrioventricular block. A triple chamber pace maker was installed. Discussion: Familial RCMs mutations are characterized by high allelic, genetic and phenotypic variability, with autosomal dominant inheritance and variable penetrance. This mutation is rarely found in RCM, it is usually reported in HCM (OMIM 160760). Genetic screening should be considered to identify patients at risk in families with suspected familial transmission. MYH7 mutations seem to be associated with severe phenotypes, earlier age of onset and more pejorative evolution than other mutations. Conclusion:The evaluation of familial RCM requires an understanding of its variable phenotypic expression and incomplete penetrance. RCM and HCM may coexist in the same family. Genetic testing for hereditary RCM should be considered when secondary causes have been excluded.

P645 Familial restrictive cardiomyopathy and Noonan"s syndrome: a rare association

Abstract Background Noonan syndrome is a rare genetic disorder. Typical cardiac involvement include pulmonary stenosis and hypertrophic cardiomyopathy. We present the association of Noonan syndrome with familial non-hypertrophic cardiomyopathy with haemodynamic features of restrictive physiology. Case description. A 30-year old male patient presented to the outpatient clinic with clinical symptoms of heart failure which was slowly progressive since age 20. He was found to have features of restrictive cardiomyopathy aged 12 years at the time when his mother was diagnosed with Noonan syndrome and restrictive cardiomyopathy. On examination, his 1st and 2nd heart sounds were normal, however 3rd heart sound was present. Pulse was regular, 75 per minute, BP 110/70 mmHg. Chest was clear and saturation 98%. Echocardiography showed small left ventricle (LV) with preserved ejection fraction (EF), borderline LV wall thickness (10-11 mm), restrictive filling pattern with mitral valve E/A ratio 4.2 and deceleration time 68 ms; dilated both atria; and pulmonary artery systolic pressure of 37 mmHg (Figure, panels A-C; F). Prominent late diastolic reversal flow was noted in hepatic veins (Panel D). LV longitudinal strain was borderline in absolute value (-18%) however demonstrated ‘apical sparing’ pattern (Panel E). The right ventricle was small in size with mild hypertrophy and dynamic function, but normal flow through pulmonary valve. Prominent diastolic reversal flow was also noted in superior vena cava. Cardiac magnetic resonance confirmed echocardiographic findings and additionally demonstrated prominent trabeculations and myocardial crypts in the LV, small pericardial effusion; no signs of amyloidosis, myocardial infarction, infiltration or fibrosis. Right heart catheterisation showed borderline pulmonary hypertension with a mean pressure of 25 mmHg, raised pulmonary artery wedge pressure 18 mmHg, normal pulmonary vascular resistance 1.9 WU, and a ‘square root sign’ (Panel G). Patient underwent cardiopulmonary exercise testing, he stopped after 9 mins of Bruce protocol due to fatigue, reaching the Peak VO2 of 21.1ml/kg/min (49% of predicted value). No ST changes or arrhythmic events were noted. Patient was diagnosed with primary (non-infiltrative) familial restrictive cardiomyopathy and discussed at multidisciplinary team meeting with recommendation of close follow-up for timing for heart transplantation. Meanwhile he was encouraged to continue treatment with ramipril and start regular physical activity. Discussion There are only few reports describing familial non-hypertrophic cardiomyopathy in patients with Noonan syndrome and none in their family members. We review typical clinical and diagnostic features of restrictive cardiomyopathy involving both ventricles and raise awareness of clinicians of primary familial restrictive cardiomyopathy as a possible cardiac manifestation in patients with Noonan syndrome and their immediate family members. Abstract P645 Figure.

The clinical case of familial restrictive cardiomyopathy

Restrictive cardiomyopathy often results in chronic heart failure. Knowledge of family history and genetic examination are extremely important for the early diagnostics of a family restrictive cardiomyopathy and prescription of non-specific therapy. The article describes clinical case of familial restrictive cardiomyopathy with a burdened family history.

A rare case of familial restrictive cardiomyopathy, with mutations in MYH7 and ABCC9 genes.

Restrictive cardiomyopathy is the least common type of cardiomyopathy, being defined by diastolic dysfunction and often unimpaired systolic function. Restrictive cardiomyopathies can be classified as familial or non-familial. Patients with familial restrictive cardiomyopathy can develop signs and symptoms of this condition anytime from childhood to adulthood. The evolution of the disease is towards signs and symptoms of pulmonary and systemic congestion and, without treatment, there is a five-year mortality rate of approximately 30% in these patients. We discuss the case of a 43-year-old patient diagnosed with familial restrictive cardiomyopathy with positive genetic tests for mutations of MYH7 gene and ABCC9 gene, who was first hospitalized in 2011 for palpitations. The echocardiography performed in evolution showed a continuous alteration of right ventricle function, without important differences of left ventricular function.  She developed heart failure symptoms six years after diagnosis and she had seven hospitalizations in the past two years, currently with an increasing need of diuretics and persistent hepatic dysfunction. Cardiac transplantation or left ventricular assist device therapy should be considered in patients with severe heart failure symptoms and no longer effective treatment. However, elevated pulmonary vascular resistance excludes the patient from cardiac transplantation.

Response by Roldan-Sevilla to Letter Regarding Article, “Missense Mutations in the FLNC Gene Causing Familial Restrictive Cardiomyopathy”

Response by Roldan-Sevilla to Letter Regarding Article, “Missense Mutations in the FLNC Gene Causing Familial Restrictive Cardiomyopathy”

Cover Image, Volume 37, Issue 3

Human MutationVolume 37, Issue 3 Cover ImageFree Access Cover Image, Volume 37, Issue 3 First published: 11 February 2016 https://doi.org/10.1002/humu.22968AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract On the cover: The cover image, by Brenda Gerull et al., is based on the Research Article, Mutations in FLNC are Associated with Familial Restrictive Cardiomyopathy, DOI:10.1002/humu.22942. Volume37, Issue3March 2016 RelatedInformation

Mutations inFLNCare Associated with Familial Restrictive Cardiomyopathy

Individuals affected by restrictive cardiomyopathy (RCM) often develop heart failure at young ages resulting in early heart transplantation. Familial forms are mainly caused by mutations in sarcomere proteins and demonstrate a common genetic etiology with other inherited cardiomyopathies. Using next-generation sequencing, we identified two novel missense variants (p.S1624L; p.I2160F) in filamin-C (FLNC), an actin-cross-linking protein mainly expressed in heart and skeletal muscle, segregating in two families with autosomal-dominant RCM. Affected individuals presented with heart failure due to severe diastolic dysfunction requiring heart transplantation in some cases. Histopathology of heart tissue from patients of both families showed cytoplasmic inclusions suggesting protein aggregates, which were filamin-C specific for the p.S1624L by immunohistochemistry. Cytoplasmic aggregates were also observed in transfected myoblast cell lines expressing this mutant filamin-C indicating further evidence for its pathogenicity. Thus, FLNC is a disease gene for autosomal-dominant RCM and broadens the phenotype spectrum of filaminopathies.

MUTATIONS IN FILAMIN C CAUSE FAMILIAL RESTRICTIVE CARDIOMYOPATHY

Restrictive cardiomyopathy (RCM) is characterized by increased stiffness of the ventricles, impaired diastolic filling with preserved systolic function. Familial RCM is a rare condition and mainly caused by mutations sarcomere proteins and desmin. Filamin C (FLNC) is a muscle specific protein which provides the mechanical link between the extracellular matrix, the plasma membrane and the actin cytoskeleton. Mutations in FLNC are known to cause myofibrillar myopathy (MFM) and most recently suggested to be associated with hypertrophic cardiomyopathy (HCM). Purpose: In families with autosomal dominant RCM we excluded mutations in all known genes for RCM and aimed to identify and validate a novel cause of the disease. Cardiovascular assessment was done in all available family members after the index case was diagnosed with early onset RCM leading to heart transplantation. Genetic studies via next generation sequencing (NGS) have been performed followed by segregation analysis in affected family members. Explanted heart tissue has been evaluated by histology and immunohistochemistry. Functional analysis of mutated FLNC proteins were carried out in cultured cells and analyzed by immunocytochemistry. The index case presented with heart failure at the age of 13 years requiring heart transplantation a year later. Cardiac assessment showed an impaired diastolic filling pattern, enlarged atria, normal systolic LV-function and wall thicknesses suggesting restrictive cardiomyopathy. Subsequently other family members were diagnosed with signs of RCM. Years later her 2 year old daughter also required heart transplantation due to RCM. Genetic studies via Next Generation Sequencing (NGS) found a unique variant in FLNC (p.S1624L) segregating with the disease. Histopathology and immunohistochemistry revealed FLNC specific cytoplasmic aggregates. Further expression of mutant FLNC proteins in C2C12 and H9C2 cells showed perinuclear and cytoplasmic aggregates not observed in wild-type FLNC transfected cells. Finding of a second mutation in a different family with RCM discovered by NGS confirmed the involvement of FLNC in the genetic aetiology of RCM. Mutations in FLNC are a novel cause of familial autosomal dominant RCM. It demonstrates the powerful strategy of NGS to uncover novel genetic causes for familial diseases.

Disturbance in Z-Disk Mechanosensitive Proteins Induced by a Persistent Mutant Myopalladin Causes Familial Restrictive Cardiomyopathy

BackgroundFamilial restrictive cardiomyopathy (FRCM) has a poor prognosis due to diastolic dysfunction and restrictive physiology (RP). Myocardial stiffness, with or without fibrosis, underlie RP, but the mechanism(s) of restrictive remodeling is unclear. Myopalladin (MYPN) is a messenger molecule that links structural and gene regulatory molecules via translocation from the Z-disk and I-bands to the nucleus in cardiomyocytes. Expression of N-terminal MYPN peptide results in severe disruption of the sarcomere. ObjectivesThe aim was to study a nonsense MYPN-Q529X mutation previously identified in the FRCM family in an animal model to explore the molecular and pathogenic mechanisms of FRCM. MethodsFunctional (echocardiography, cardiac magnetic resonance [CMR] imaging, electrocardiography), morphohistological, gene expression, and molecular studies were performed in knock-in heterozygote (MypnWT/Q526X) and homozygote mice harboring the human MYPN-Q529X mutation. ResultsEchocardiographic and CMR imaging signs of diastolic dysfunction with preserved systolic function were identified in 12-week-old MypnWT/Q526X mice. Histology revealed interstitial and perivascular fibrosis without overt hypertrophic remodeling. Truncated MypnQ526X protein was found to translocate to the nucleus. Levels of total and nuclear cardiac ankyrin repeat protein (Carp/Ankrd1) and phosphorylation of mitogen-activated protein kinase/extracellular signal–regulated kinase 1/2 (Erk1/2), Erk1/2, Smad2, and Akt were reduced. Up-regulation was evident for muscle LIM protein (Mlp), desmin, and heart failure (natriuretic peptide A [Nppa], Nppb, and myosin heavy chain 6) and fibrosis (transforming growth factor beta 1, alpha–smooth muscle actin, osteopontin, and periostin) markers. ConclusionsHeterozygote MypnWT/Q526X knock-in mice develop RCM due to persistence of mutant MypnQ526X protein in the nucleus. Down-regulation of Carp and up-regulation of Mlp and desmin appear to augment fibrotic restrictive remodeling, and reduced Erk1/2 levels blunt a hypertrophic response in MypnWT/Q526X hearts.

Molecular basis for clinical heterogeneity in inherited cardiomyopathies due to myopalladin mutations

Abnormalities in Z-disc proteins cause hypertrophic (HCM), dilated (DCM) and/or restrictive cardiomyopathy (RCM), but disease-causing mechanisms are not fully understood. Myopalladin (MYPN) is a Z-disc protein expressed in striated muscle and functions as a structural, signaling and gene expression regulating molecule in response to muscle stress. MYPN was genetically screened in 900 patients with HCM, DCM and RCM, and disease-causing mechanisms were investigated using comparative immunohistochemical analysis of the patient myocardium and neonatal rat cardiomyocytes expressing mutant MYPN. Cardiac-restricted transgenic (Tg) mice were generated and protein-protein interactions were evaluated. Two nonsense and 13 missense MYPN variants were identified in subjects with DCM, HCM and RCM with the average cardiomyopathy prevalence of 1.66%. Functional studies were performed on two variants (Q529X and Y20C) associated with variable clinical phenotypes. Humans carrying the Y20C-MYPN variant developed HCM or DCM, whereas Q529X-MYPN was found in familial RCM. Disturbed myofibrillogenesis with disruption of α-actinin2, desmin and cardiac ankyrin repeat protein (CARP) was evident in rat cardiomyocytes expressing MYPN(Q529X). Cardiac-restricted MYPN(Y20C) Tg mice developed HCM and disrupted intercalated discs, with disturbed expression of desmin, desmoplakin, connexin43 and vinculin being evident. Failed nuclear translocation and reduced binding of Y20C-MYPN to CARP were demonstrated using in vitro and in vivo systems. MYPN mutations cause various forms of cardiomyopathy via different protein-protein interactions. Q529X-MYPN causes RCM via disturbed myofibrillogenesis, whereas Y20C-MYPN perturbs MYPN nuclear shuttling and leads to abnormal assembly of terminal Z-disc within the cardiac transitional junction and intercalated disc.

Familial Restrictive Cardiomyopathy With 12 Affected Family Members

The investigators describe idiopathic restrictive cardiomyopathy in a 50-year-old woman. Eleven other family members had cerebrovascular accidents, arrhythmias, and/or heart failure requiring cardiac transplantation. The patient developed dyspnea and palpitations at 19 years of age, when echocardiography demonstrated normal left ventricular systolic function, biatrial enlargement, and a restrictive Doppler mitral inflow pattern; restrictive hemodynamics were confirmed on cardiac catheterization. She was managed for many years with diuretics, antiarrhythmic agents, and anticoagulation and underwent cardioversion for recurrent atrial fibrillation. In conclusion, the patient ultimately underwent cardiac transplantation. Idiopathic restrictive cardiomyopathy (IRC) is an uncommon cardiac disorder characterized by left ventricular (LV) diastolic dysfunction with normal LV systolic function and wall thickness and symptoms of heart failure. We report

Idiopathic restrictive cardiomyopathy in children is caused by mutations in cardiac sarcomere protein genes

Background:Restrictive cardiomyopathy (RCM) is rare in childhood, but has a grave prognosis. The cause of disease in most cases is unknown.Objective:To determine the prevalence of sarcomere protein gene mutations in...

Familial restrictive cardiomyopathy with skeletal abnormalities

A family is described in which 5 of 9 living children were found to have restrictive cardiomyopathy associated with skeletal muscle and orthopedic abnormalities. In the absence of another identifiable etiology, a genetic cause for restrictive cardiomyopathy in this family is probable. Consistent with the poor prognosis encountered for children with restrictive cardiomyopathy, 2 children in this family died, whereas a third was symptomatic by age 3 years.

Familial restrictive cardiomyopathy caused by a missense mutation in the desmin gene: possible role of apoptosis in disease pathogenesis

Familial restrictive cardiomyopathy caused by a missense mutation in the desmin gene: possible role of apoptosis in disease pathogenesis

National Health Service

<h3>Background:</h3> Restrictive cardiomyopathy (RCM) is rare in childhood, but has a grave prognosis. The cause of disease in most cases is unknown. <h3>Objective:</h3> To determine the prevalence of sarcomere protein gene mutations in children with idiopathic RCM. <h3>Methods:</h3> Twelve patients (9 female, mean age 5.1 years) with idiopathic RCM referred between 1991 and August 2006 underwent detailed clinical and genetic evaluation. Nine had received cardiac transplants at the time of the study. The entire coding sequences of the genes encoding eight cardiac sarcomere proteins and desmin were screened for mutations. Familial evaluation was performed on first-degree relatives. <h3>Results:</h3> Four patients (33%) had a family history of cardiomyopathy: RCM (n = 2); dilated cardiomyopathy (n = 1) and left ventricular non-compaction (n = 1). Sarcomere protein gene mutations were identified in four patients (33%): 2 in the cardiac troponin I gene (TNNI3) and 1 each in the troponin T (TNNT2) and α-cardiac actin (ACTC) genes. Two were de novo mutations and 3 were new mutations. All mutations occurred in functionally important and conserved regions of the genes. <h3>Conclusions:</h3> Sarcomere protein gene mutations are an important cause of idiopathic RCM in childhood. We describe the first mutation in ACTC in familial RCM. The identification of RCM in a child should prompt consideration of sarcomere protein disease as a possible cause and warrants clinical evaluation of the family.