Cardiac amyloidosis in a patient with multiple myeloma: a case report and review of literature

We report a case of a 52-year-old man with multiple myeloma and rapidly progressive heart failure who died unexpectedly from a probable arrhythmia. Postmortem examination revealed infiltrative amyloid cardiomyopathy, a rare cause of predominantly diastolic myocardial disease. Cardiac amyloidosis should be considered in any patient presenting with congestive heart failure, preserved systolic function, and a discrepancy between a low QRS voltage on electrocardiography and an apparent left ventricular hypertrophy on sonogram. The pattern of left ventricular diastolic dysfunction changes during the course of amyloidosis and the classically described restrictive physiology occurs only in advanced stages of the disease.

Extracardiac medical and neuromuscular implications in restrictive cardiomyopathy

Restrictive cardiomyopathy (RCMP) is characterized by restrictive filling and reduced diastolic volume of either or both ventricles with normal or near-normal systolic function and wall thickness. It may occur idiopathically or as a cardiac manifestation of systemic diseases such as scleroderma, amyloidosis, Churg-Strauss syndrome, cystinosis, sarcoidosis, lymphoma, Gaucher's disease, hemochromatosis, Fabry's disease, pseudoxanthoma elasticum, hypereosinophilic syndrome, carcinoid, Noonan's syndrome, reactive arthritis, or Werner's syndrome and various neuromuscular disorders. Whereas in idiopathic RCMP the therapeutic options are only treatment of cardiac congestion, in cases with an underlying disorder, a causal therapy may be available. Patients with RCMP should be investigated as soon as the cardiac diagnosis is established for extracardiac diseases to detect a possibly treatable cause of RCMP before the disease becomes intractable. These investigations include a diligent clinical history and examination, blood tests, and ophthalmologic, otologic, dermatologic, gastroenterologic, nephrologic, hematologic, and neurologic examinations. If extracardiac examinations do not reveal a plausible cause for RCMP, endomyocardial biopsy is indicated.

Deletion in TNNI3 gene is associated with restrictive cardiomyopathy

In dilated and hypertrophic cardiomyopathies, over ten disease-causing genes have been identified in each entity. In contrast, mutations in only desmin and cardiac troponin T and I (TNNI3) have been shown to cause restrictive cardiomyopathy (RCM). We applied a candidate gene approach and identified a novel one nucleotide deletion, resulting in frame shift and predicted formation of a premature stop codon, deletion of part of exon 7 and all exon 8, and truncation of significant C-terminal portion of TNNI3. Western blot analysis showed approximately 50% reduction of total troponin I content in myocardial tissue. The clinical hallmark was a restrictive type of cardiac hemodynamics, and congestive heart failure, leading to the death of the patient at the age of 28.

Mutation in the alpha-cardiac actin gene associated with apical hypertrophic cardiomyopathy, left ventricular non-compaction, and septal defects

AIMS

The E101K mutation in the alpha-cardiac actin gene (ACTC) has been associated with apical hypertrophic cardiomyopathy (HCM). As prominent trabeculations were described in some carriers, we screened for the E101K mutation in our index patients with HCM, dilated cardiomyopathy (DCM), or left ventricular non-compaction (LVNC).

METHODS AND RESULTS

Clinical, echocardiographic, and genetic screening by restriction fragment length polymorphism of the ACTC E101K mutation in 247 families with HCM, DCM, or LVNC. The mutation was found in five index patients (one with LVNC and four with HCM). Clinical and morphological data were obtained from 94 family members. Forty-six individuals had cardiomyopathy (43 with the mutation and three with no genetic study): 23 fulfilled criteria for LVNC, 22 were diagnosed as apical HCM, and one had been diagnosed as restrictive cardiomyopathy. There had been one heart transplant and one congestive heart failure death in patients with severe diastolic dysfunction, and five premature sudden deaths. The E101K mutation was not found in 48 unaffected relatives. Septal defects (eight atrial and one ventricular) were found in nine mutant carriers from four families, and were absent in relatives without the mutation (P = 0.003).

CONCLUSION

LVNC and HCM may appear as overlapping entities. The ACTC E101K mutation should be considered in the genetic diagnosis of LVNC, apical HCM, and septal defects.

Prevalence, clinical significance, and genetic basis of hypertrophic cardiomyopathy with restrictive phenotype

OBJECTIVES

The purpose of this study was to determine the prevalence, clinical significance, and genetic basis of hypertrophic cardiomyopathy (HCM) with "restrictive phenotype" characterized by restrictive filling and minimal or no left ventricular hypertrophy.

BACKGROUND

Hypertrophic cardiomyopathy is a heterogeneous myocardial disorder with a broad spectrum of clinical presentation and morphologic features. Recent reports indicated that some patients with restrictive cardiomyopathy, which is an uncommon condition defined by restrictive filling and reduced diastolic volumes with normal or near normal left ventricular wall thickness and contractile function, have features suggestive of HCM with mutations in cardiac troponin I, myocyte disarray at explant/autopsy, and relatives with HCM. Systematic evaluation of the restrictive phenotype in HCM patients has not been performed.

METHODS

We evaluated 1,226 patients from 688 consecutive HCM families to identify individuals who fulfilled diagnostic criteria for "restrictive phenotype."

RESULTS

Nineteen of 1,226 affected individuals (1.5%) from 16 families (2.3%) had the "restrictive phenotype." During follow up (53.7 +/- 49.2 months), 17 patients (89%) experienced dyspnea (New York Heart Association functional class > or =2). The 5-year survival rate from all-cause mortality, cardiac transplantation, or implantable cardioverter-defibrillator discharge was 56.4%. Mutation analysis for 5 sarcomere genes was feasible in 15 of 16 probands. Mutations were found in 8: 4 in beta-myosin heavy chain, and 4 in cardiac troponin I.

CONCLUSIONS

The "restrictive phenotype" in isolation is an uncommon presentation of the clinical spectrum of HCM and is associated with severe limitation and poor prognosis. This phenotype may be associated with beta-myosin heavy chain and cardiac troponin I mutations.

Thin Filament Disinhibition by Restrictive Cardiomyopathy Mutant R193H Troponin I Induces Ca 2+ -Independent Mechanical Tone and Acute Myocyte Remodeling

Inherited restrictive cardiomyopathy (RCM) is a debilitating disease characterized by a stiff heart with impaired ventricular relaxation. Mutations in cardiac troponin I (cTnI) were identified as causal for RCM. Acute genetic engineering of adult cardiac myocytes was used to identify primary structure/function effects of mutant cTnI. Studies focused on R193H cTnI owing to the poor prognosis of this allele. Compared with wild-type cTnI, R193H mutant cTnI more effectively incorporated into the sarcomere, where it exerted dose-dependent effects on basal and dynamic contractile function. Under loaded conditions, permeabilized myocyte Ca 2+ sensitivity of tension was increased, whereas the passive tension–extension relationship was not altered by R193H cTnI. Normal rod-shaped myocyte morphology acutely transitioned to a “short-squat” phenotype in concert with progressive stoichiometric incorporation of R193H in the absence of altered diastolic Ca 2+ . The specific myosin inhibitor blebbistatin fully blocked this transition. Heightened Ca 2+ buffering by the R193H myofilaments, and not alterations in Ca 2+ handling by the sarcoplasmic reticulum, slowed the decay rate of the Ca 2+ transient. Incomplete mechanical relaxation conferred by R193H was exacerbated at increasing pacing frequencies independent of elevated diastolic Ca 2+ . R193H cTnI–dependent mechanical tone caused acute remodeling to a quasicontracted state not elicited by other Ca 2+ -sensitizing proteins and is a direct correlate of the stiff heart characteristic of RCM in vivo. These results point toward targets downstream of Ca 2+ handling, notably thin filament regulation and actin–myosin interaction, in designing therapeutic strategies to redress the primary cell morphological and mechanical underpinnings of RCM.

[Mutations genes in primarly cardiomyopathies]

Diagnosis of primarly cardiomypathies refers to genes discorders in chromosomes. Aim of this paper is to show genetics and molecular knowledges published so far. Familiar form hypertrophic cardiomyopathy is hereditable autosomatically dominantly in any of 10 genes that regulate contractile, structural and regulative function with predomination of mutation in gene for heavy chaire of myocardiac beta myosin localized at 14 chromosome (more than 200 mutation). Sporadic forms appears autosomatically recessively as the result of new mutation or as non-genetic form. Familiar dilated cardiomyopathy is associated with mutation more than 10 genes with frequent mutation of genes (beta myosin of heavy chain, cardiac T throponin, phospholamban and cardiospecific free methavinculin genes) and with clinical features that are mainly uknown (associated with peripheral myopathies). Restrictive cardiomyopathy is considered that the idiopathic restrictice cardiomyopathies has, also, hereditable atiology. A lot of the ries explain genes of this cardiomyopathy with predomination of heredithy with autosomatically dominant type (desmoplacin mutation) with variable expression of genes at 14, 1, 2, 3, 17 and 18 chromosome with programmed myocit death-apoptosis.

Desmin mutations in a St. Petersburg cohort of cardiomyopathies

Several desmin mutations have been described over the past few years in patients with dilated and restrictive cardiomyopathy, often in association with distal myopathy. However, the role of desmin mutations as a cause of various types of cardiomyopathy is still undetermined. The aim of this study was to analyse the frequency of desmin mutations in patients with cardiomyopathy identified and diagnosed in the St. Petersburg area of Russia. We screened 98 patients with dilated, 40 with hypertrophic and 4 with restrictive cardiomyopathy. All exons of the desmin gene were amplified by PCR and studied by sequencing. Two out of 98 patients showed the presence of desmin gene mutations, not previously described in dilated cardiomyopathy. A novel IVS2-2A-->G splice site mutation, presumably causing skipping of exon 3, was detected in a case of familial right ventricular dilated cardiomyopathy. An A213V mutation was associated with a case of late onset dilated cardiomyopathy. No desmin mutations were found in patients with hypertrophic or restrictive cardiomyopathy. Desmin mutations should be considered a relatively rare cause of dilated cardiomyopathy in this specific geographic area.

A point mutation (R192H) in the C-terminus of human cardiac troponin I causes diastolic dysfunction in transgenic mice

Cardiac troponin I (cTnI) mutations have been linked to the development of restrictive cardiomyopathy (RCM) in human patients. We modeled one mutation in human cTnI C-terminus, arginine192-->histidine (R192H) by cardiac specific expression of the mutated protein (cTnI(193His) in mouse sequence) in transgenic mice. Heart tissue sections revealed neither significant hypertrophy nor ventricular dilation in cTnI(193His) mice. The main functional alteration detected in cTnI(193His) mice by ultrasound cardiac imaging examinations was impaired cardiac relaxation manifested by a decreased left ventricular end diastolic dimension (LVEDD) and an increased end diastolic dimension in both atria. The cardiac ejection fraction (EF) was not significant changed in 6- to 8-week-old cTnI(193His) mice, however, the EF was significantly decreased in cTnI(193His) mice at age of 11 months. These data indicate that individual genetic conditions and environmental factors participate together in the development of the cTnI mutation based-cardiac muscle disorders. This mouse model provides us with a tool to further investigate the pathophysiology and the development of RCM.

Desmin accumulation restrictive cardiomyopathy and atrioventricular block associated with desmin gene defects

BACKGROUND

Primary desminopathies are caused by desmin gene [DES (MIM*125660)] mutations. The clinical spectrum includes pure myopathies, cardiomuscular diseases and cardiomyopathies. Patients with restrictive cardiomyopathy (RCM) plus atrioventricular block (AVB) due to DES defects are frequently unrecognized unless desmin accumulation is specifically investigated in endomyocardial biopsy (EMB) by ultrastructural study.

AIMS

To describe a cardiological phenotype characterized by RCM plus AVB due to desmin accumulation caused by DES defects.

METHODS AND RESULTS

Desmin accumulation was diagnosed by means of ultrastructural and immunocytochemical studies of EMB in four unrelated probands with RCM and AVB. Candidate genes [DES and alphaB-crystallin (CRYAB)] were screened using sequence analysis. Four DES gene mutations were identified: three new (R16C, T453I and a 10 bp deletion at the exon-intron boundary of exon 3 disrupting the donor splice site) and one known (R406W). The disease was autosomal dominant in two families, recessive in one and associated with a de novo mutation in one. The mutations cosegregated with phenotype in all patients. CRYAB gene screening was negative.

CONCLUSIONS

A cardiac phenotype characterized by RCM and AVB caused by desmin accumulation is associated with DES mutations. Although the mutations affected different domains, the cardiac phenotype was identical.

Restrictive cardiomyopathy with atrioventricular conduction block resulting from a desmin mutation

BACKGROUND

According to the predominant view, desmin mutations cause dilated cardiomyopathy (DCM). We evaluated a family with restrictive cardiomyopathy (RCM) associated with a novel desmin mutation and reviewed recent reports regarding the frequency of RCM in patients with desmin myopathy.

METHODS

Cardiovascular examination was performed in three affected and five at-risk members of a family from Poland, histopathologic study of skeletal muscle biopsy was done in a single patient, and functional analysis of mutant desmin protein was carried out in cultured cells.

RESULTS

Cardiovascular assessment led to the diagnosis of RCM in affected family members. Histopathological study of skeletal muscle biopsy revealed features characteristic of desmin myopathy. A novel desmin E413K mutation was identified in each affected family member, but not unrelated controls. The pathogenicity of the E413K mutation was confirmed in transfected cell cultures showing inability of mutant desmin to form a cellular filamentous network or support a pre-existing network formed by other intermediate filaments. Three-dimensional modeling and electrostatic calculations indicated that the E413K mutation located in a functionally unique domain of desmin molecule potentially disrupts intramolecular interactions. Analysis of previously reported observations indicates that RCM in desminopathy patients may be as frequent as DCM.

CONCLUSIONS

A novel E413K mutation in desmin caused autosomal dominant RCM rather than DCM. The location of the E413K mutation at a highly conserved end of the alpha-helical rod domain may be related to the phenotypic differences from the previously described DCM-associated desmin mutations. Functional and structural analyses of mutant desmin allowed to identify likely pathogenic mechanisms.

Genetic linkage of a novel autosomal dominant restrictive cardiomyopathy locus

BACKGROUND

In recent years, non-syndromic idiopathic cardiomyopathies have increasingly been characterised as autosomal dominant conditions caused by single gene mutations. Loci have been identified for hypertrophic and dilated cardiomyopathy, and in some cases the same loci are associated with restrictive cardiomyopathy (RCM). In a kindred with RCM that we previously reported, we ruled out the known cardiomyopathy loci and other candidate genes by linkage analysis and mutation screening.

METHODS AND RESULTS

Here we report a genome-wide analysis in this family that has resulted in linkage to a region on chromosome 10.

CONCLUSIONS

There are no genes in the interval that are known to cause idiopathic cardiomyopathy, and thus this linkage represents localisation of a new RCM locus.

Infantile restrictive cardiomyopathy resulting from a mutation in the cardiac troponin T gene

Here we report the first infantile case of restrictive cardiomyopathy caused by a de novo mutation of the cardiac troponin T gene. The patient presented with an apparent life-threatening event. She developed malignant arrhythmias and hemodynamic instability, requiring initial rescue support with extracorporeal membrane oxygenation, and subsequently underwent insertion of a biventricular assist device (VAD). She successfully received an orthotopic heart transplant 172 days after VAD implantation.

The genetic basis for cardiac remodeling

Cardiomyopathies are primary disorders of cardiac muscle associated with abnormalities of cardiac wall thickness, chamber size, contraction, relaxation, conduction, and rhythm. They are a major cause of morbidity and mortality at all ages and, like acquired forms of cardiovascular disease, often result in heart failure. Over the past two decades, molecular genetic studies of humans and analyses of model organisms have made remarkable progress in defining the pathogenesis of cardiomyopathies. Hypertrophic cardiomyopathy can result from mutations in 11 genes that encode sarcomere proteins, and dilated cardiomyopathy is caused by mutations at 25 chromosome loci where genes encoding contractile, cytoskeletal, and calcium regulatory proteins have been identified. Causes of cardiomyopathies associated with clinically important cardiac arrhythmias have also been discovered: Mutations in cardiac metabolic genes cause hypertrophy in association with ventricular pre-excitation and mutations causing arrhythmogenic right ventricular dysplasia were recently discovered in protein constituents of desmosomes. This considerable genetic heterogeneity suggests that there are multiple pathways that lead to changes in heart structure and function. Defects in myocyte force generation, force transmission, and calcium homeostasis have emerged as particularly critical signals driving these pathologies. Delineation of the cell and molecular events triggered by cardiomyopathy gene mutations provide new fundamental knowledge about myocyte biology and organ physiology that accounts for cardiac remodeling and defines mechanistic pathways that lead to heart failure.

Drastic Ca2+ sensitization of myofilament associated with a small structural change in troponin I in inherited restrictive cardiomyopathy

Six missense mutations in human cardiac troponin I (cTnI) were recently found to cause restrictive cardiomyopathy (RCM). We have bacterially expressed and purified these human cTnI mutants and examined their functional and structural consequences. Inserting the human cTnI into skinned cardiac muscle fibers showed that these mutations had much greater Ca2+-sensitizing effects on force generation than the cTnI mutations in hypertrophic cardiomyopathy (HCM). The mutation K178E in the second actin-tropomyosin (Tm) binding region showed a particularly potent Ca2+-sensitizing effect among the six RCM-causing mutations. Circular dichroism and nuclear magnetic resonance spectroscopy revealed that this mutation does not extensively affect the structure of the whole cTnI molecule, but induces an unexpectedly subtle change in the structure of a region around the mutated residue. The results indicate that the K178E mutation has a localized effect on a structure that is critical to the regulatory function of the second actin-Tm binding region of cTnI. The present study also suggests that both HCM and RCM involving cTnI mutations share a common feature of increased Ca2+ sensitivity of cardiac myofilament, but more severe change in Ca2+ sensitivity is associated with the clinical phenotype of RCM.

Mutations in human cardiac troponin I that are associated with restrictive cardiomyopathy affect basal ATPase activity and the calcium sensitivity of force development

Human cardiac Troponin I (cTnI) is the first sarcomeric protein for which mutations have been associated with restrictive cardiomyopathy. To determine whether five mutations in cTnI (L144Q, R145W, A171T, K178E, and R192H) associated with restrictive cardiomyopathy were distinguishable from hypertrophic cardiomyopathy-causing mutations in cTnI, actomyosin ATPase activity and skinned fiber studies were carried out. All five mutations investigated showed an increase in the Ca2+ sensitivity of force development compared with wild-type cTnI. The two mutations with the worst clinical phenotype (K178E and R192H) both showed large increases in Ca2+ sensitivity (deltapCa50 = 0.47 and 0.36, respectively). Although at least one of these mutations is not in the known inhibitory regions of cTnI, all of the mutations investigated caused a decrease in the ability of cTnI to inhibit actomyosin ATPase activity. Mixtures of wild-type and mutant cTnI showed that cTnI mutants could be classified into three different groups: dominant (L144Q, A171T and R192H), equivalent (K178E), or weaker (R145W) than wild-type cTnI in actomyosin ATPase assays in the absence of Ca2+. Although most of the mutants were able to activate actomyosin ATPase similarly to wild-type cTnI, L144Q had significantly lower maximal ATPase activities than any of the other mutants or wild-type cTnI. Three mutants (L144Q, R145W, and K178E) were unable to fully relax contraction in the absence of Ca2+. The inability of the five cTnI mutations investigated to fully inhibit ATPase activity/force development and the generally larger increases in Ca2+ sensitivity than observed for most hypertrophic cardiomyopathy mutations would likely lead to severe diastolic dysfunction and may be the major physiological factors responsible for causing the restrictive cardiomyopathy phenotype in some of the genetically affected individuals.

Inherited cardiomyopathies as a troponin disease

Troponin, one of the sarcomeric proteins, plays a central role in the Ca(2+) regulation of contraction in vertebrate skeletal and cardiac muscles. It consists of three subunits with distinct structure and function, troponin T, troponin I, and troponin C, and their accurate and complex intermolecular interaction in response to the rapid rise and fall of Ca(2+) in cardiomyocytes plays a key role in maintaining the normal cardiac pump function. More than 200 mutations in the cardiac sarcomeric proteins, including myosin heavy and light chains, actin, troponin, tropomyosin, myosin-binding protein-C, and titin/connectin, have been found to cause various types of cardiomyopathy in human since 1990, and more than 60 mutations in human cardiac troponin subunits have been identified in dilated, hypertrophic, and restrictive forms of cardiomyopathy. In this review, we have focused on the mutations in the genes for human cardiac troponin subunits and discussed their functional consequences that might be involved in the primary mechanisms for the pathogenesis of these different types of cardiomyopathy.

Array lessons from the heart: focus on the genome and transcriptome of cardiomyopathies

Our understanding of the cardiovascular system has evolved through the years by extensive studies emphasizing the identification of the molecular and physiological mechanisms involved in its normal function and disease pathogenesis. Major discoveries have been made along the way. However, the majority of this work has focused on specific genes or pathways rather than integrative approaches. In cardiomyopathies alone, over 30 different loci have shown mutations with varying inheritance patterns, yet mostly coding for structural proteins. The emergence of microarrays in the early 1990s paved the way to a new era of cardiovascular research. Microarrays dramatically accelerated the rhythm of discoveries by giving us the ability to simultaneously study thousands of genes in a single experiment. In the field of cardiovascular research, microarrays are having a significant contribution, with the majority of work focusing on end-stage cardiomyopathies that lead to heart failure. Novel molecular mechanisms have been identified, known pathways are seen under new light, disease subgroups begin to emerge, and the effects of various drugs are molecularly dissected. This cross-study data comparison concludes that consistent energy metabolism gene expression changes occur across dilated, hypertrophic, and ischemic cardiomyopathies, while Ca2+ homeostasis changes are prominent in the first two cardiomyopathies, and structural gene expression changes accompany mostly the dilated form. Gene expression changes are further correlated to disease genetics. The future of microarrays in the cardiomyopathy field is discussed with an emphasis on optimum experimental design and on applications in diagnosis, prognosis, and drug discovery.

The enlarging spectrum of desminopathies: new morphological findings, eastward geographic spread, novel exon 3 desmin mutation

A 52-year-old man, who had developed distal muscle weakness in legs and arms, was found to have distal muscle atrophy as well as cardiac arrhythmia. His 10-year younger brother developed restrictive cardiomyopathy at the age of 20 years, which required cardiac transplantation at the age of 41 years. Skeletal muscle biopsy specimens of the older brother revealed granulofilamentous material and plaques containing numerous proteins, foremost desmin, as did cardiac biopsy tissue. The explanted heart of the younger brother showed similar protein-rich plaques and granulofilamentous material within cardiac myocytes. A novel heterozygous Glu245Asp (E245D) missense mutation in exon 3 of the desmin gene (DES) at 2q35 was found in the older brother. While clinical data and muscle biopsy pathology of the older brother conform to the nosological spectrum of desminopathies, the early-onset cardiomyopathy, a similar cardiac pathology as in skeletal muscle tissues and a novel missense mutation in the DES gene, enlarge the nosological spectrum of desminopathies.

[Hereditary cardiomyopathies: a review. Mutation of structural proteins a common cause of hereditary cardiomyopathy]

Cardiomyopathy is a disorder of the cardiac muscle and can be either primary or secondary. The primary disorders have been classified by WHO into 4 groups based on structure and function; hypertrophic, dilated and restricted cardiomyopathies and arrythmogenic right ventricle dysplasia. During the last decade the familial nature of many of these cardiomyopathies has been elucidated and different genes have been found to be mutated and causative of disease. Certain patterns can be distinguished in the mutated genes, e.g. in general the genes causing hypertrophic cardiomyopathies code for proteins involved in the contractile apparatus, the sarcomere, and the genes causing dilated cardiomyopathy code for proteins that anchor the sarcomere to the cell membrane and extracellular matrix. This article reviews these recent genetic findings and discusses their potential clinical applicability.