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AIMS: Evidence on the relative impact of diverse genetic backgrounds associated with non-ischaemic dilated cardiomyopathy (DCM) remains contradictory. This study sought to synthesize the available data regarding long-term outcomes of different gene groups in DCM. METHODS AND RESULTS: Electronic databases were systematically screened to identify studies reporting prognostic data on pre-specified gene groups. Those included pathogenic/likely pathogenic (P/LP) variants, truncating titin variants (TTNtv), lamin A/C variants (LMNA), and desmosomal proteins. Outcomes were divided into composite adverse events (CAEs), malignant ventricular arrhythmic events (MVAEs) and heart failure events (HFEs). A total of 26 studies (n = 7255) were included in the meta-analysis and 6791 patients with genotyped DCM were analysed. Patients with P/LP variants had a higher risk for CAEs (odds ratio [OR] 2.10, 95% confidence interval [CI] 1.67-2.65), MVAEs (OR 1.86, 95% CI 1.52-2.26), and HFEs (OR 2.01, 95% CI 1.08-3.73) than genotype-negative patients. The presence of TTNtv was linked to a higher risk for CAEs (OR 1.78, 95% CI 1.20-2.63), but not MVAEs or HFEs. LMNA and desmosomal groups suffered a higher risk for CAEs, MVAEs, and HFEs compared to non-LMNA and non-desmosomal groups, respectively. When genes were indirectly compared, the presence of LMNA resulted in a more detrimental effect that TTNtv, with respect to all composite outcomes but no significant difference was found between LMNA and desmosomal genes. Desmosomal genes harboured a higher risk for MVAEs compared to TTNtv. CONCLUSIONS: Different genetic substrates associated with DCM result in divergent natural histories. Routine utilization of genetic testing should be employed to refine risk stratification and inform therapeutic strategies in DCM.

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Background: The diagnosis of arrhythmogenic cardiomyopathy (ACM) is challenging especially in children at risk of adverse events. Analysis of cardiac myocyte junctional protein distribution may have diagnostic and prognostic implications, but its utility is limited by the need for a myocardial sample. We previously reported that buccal mucosa cells show junctional protein redistribution similar to that seen in cardiac myocytes of adult patients with ACM. Objectives: We aimed to determine when junctional protein distribution abnormalities first occur in children with ACM variants and whether they correlate with progression of clinically apparent disease. Methods: We analyzed buccal mucosa samples of children and adolescents with a family history of ACM (n = 13) and age-matched controls (n = 13). Samples were immunostained for plakoglobin, desmoplakin, plakophilin-1 and connexin43 and analyzed by confocal microscopy. All participants were swabbed at least twice with an average interval of 12-18 months between samplings. Results: Junctional protein re-localization in buccal mucosa cells did not correlate with the presence of ACM-causing variants but instead occurred with clinical onset of disease. No changes in protein distribution were seen unless and until there was clinical evidence of disease. In addition, progressive shifts in the distribution of key proteins correlated with worsening of the disease phenotype. Finally, we observed restoration of junctional signal for Cx43 in patient with a favorable response to anti-arrhythmic therapy. Conclusions: Due to ethical concerns about obtaining heart biopsies in children with no apparent disease, it has not been possible to analyze molecular changes in cardiac myocytes with the onset/progression of clinical disease. Using buccal smears as a surrogate for the myocardium may facilitate future studies of mechanisms and pathophysiological consequences of junctional protein redistribution in ACM. Buccal cells may also be a safe and inexpensive tool for risk stratification and potentially monitoring response to treatment in children bearing ACM variants.

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In this graphical review we focus on the structural characteristics of desmosomal proteins, their interactions with each other and with the intermediate filament cytoskeleton. The wealth of structural information that is now available allows predictions to be made about the pathogenic effect of disease-causing mutations. We have selected representative examples of missense mutations that are buried, semi-buried or surface exposed, and demonstrate how such variants could affect the structural fold of desmosomal proteins that are expressed in the heart. We explain how such alterations could compromise desmosomal adhesion, resulting in life threatening diseases including arrhythmogenic right ventricular cardiomyopathy.

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BACKGROUND: ARVC is a rare genetic-related disease characterized by fibrous fat replacement in the ventricular myocardium, caused by mutations in genes encoding for the desmosomal proteins, such as the desmoglein-2 gene (DSG2). It is reported in the literature that other genetic factors may play a role in disease penetrance. Herein, we report a Chinese proband with ARVC, which was probably caused by DSG2 p.Val149Ile mutation as genetic background when carrying heterozygous PRRT2 p.Arg217ProfsTer8 mutation. CASE PRESENTATION: A 17-year-old male with a history of paroxysmal kinesigenic dyskinesia (PKD) presented to the hospital for syncope induced by ventricular tachycardia. According to relevant clinical data and the diagnostic criteria of ARVC, a precise positive diagnosis of ARVC was finally made. Gene testing revealed that the patient carried a DSG2 heterozygous missense mutation (NM_001943: exon5: c.445G>A, p.Val149Ile) as well as frameshift mutation of PRRT2 (NM_001256442: exon2: p. Arg217Profs Ter8). CONCLUSION: This is the first time to report a Chinese proband with ARVC and a history of PKD carrying both DSG2 p. val149ile mutation and PRRT2 p. Arg217ProfsTer8 mutation, which can provide a new direction for gene screening of patients with ARVC and further supplements for its diagnostic criteria.

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Cell-adhesion complex within a tissue is important for its stability, structural integrity, functioning, cellular migration and morphogenesis. Disruption of desmosomal cell-adhesions complex results in epithelial conditions such as epidermolysis bullosa and bullous pemphigoid. Desmosome assembly and disassembly is regulated post-translationally by calcium, kinase/phosphatase activity, proteolytic processing, and also through adhesive junctions. Altered functions of desmosomal proteins desmocollin and desmoglein can cause blistering disorders, such as pemphigus foliaceus and pemphigus vulgaris, and non-Hodgkin Lymphoma while defective desmoplakin can cause supra-basal clefting in epithelium and conditions such as Carvajal syndrome, palmo-plantar keratoderma etc. This review summarises major functions of demosomal complex family and how mis-regulation of demosomal structural proteins occur in pathogenesis of non-, pre- and malignant oral lesions with disrupted epithelium.

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Arrhythmogenic right ventricular cardiomyopathy (ARVC) is the most common phenotype described within the spectrum of arrhythmogenic cardiomyopathies. It usually presents in early adolescence with severe ventricular arrhythmias along with cardiac structural and functional alterations mainly of the right ventricular myocardium. Though the estimated prevalence of ARVC in the general population is only 1:5000, it represents one of the most common causes of juvenile sudden death. However, detection of early RV dysfunction in ARVC may be challenging requiring high clinical suspicion and an algorithmic approach. A thorough family history of juvenile sudden death, ventricular arrhythmias and ICD implants should always be sought. Diagnosis usually requires electrocardiographic interpretation as well as cardiac imaging. In this article, the key diagnostic steps in the assessment of ARVC and diagnostic red flags that aid its differential diagnosis are discussed.

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Disruption of cell-cell junctions and the concomitant loss of polarity, downregulation of tumor-suppressive adherens junctions and desmosomes represent hallmark phenotypes for several different cancer cells. Moreover, a variety of evidence supports the argument that these two common phenotypes of cancer cells directly contribute to tumorigenesis. In this study, we aimed to determine the status of intercellular junction proteins expression in JJ012 human malignant chondrosarcoma cells and investigate the effect of the antitumorigenic cytokine, proline-rich polypeptide-1 (PRP-1) on their expression. The cell junction pathway array data indicated downregulation of desmosomal proteins, such as desmoglein (1,428-fold), desmoplakin (620-fold) and plakoglobin (442-fold). The tight junction proteins claudin 11 and E-cadherin were also downregulated (399- and 52-fold, respectively). Among the upregulated proteins were the characteristic for tumors gap junction ß-5 protein (connexin 31.1) and the pro-inflammatory pathway protein intercellular adhesion molecule (upregulated 129- and 43-fold, respectively). We demonstrated that PRP-1 restored the expression of the abovementioned downregulated in chondrosarcoma desmosomal proteins. PRP-1 inhibited H3K9-specific histone demethylase activity in chondrosarcoma cells in a dose-dependent manner (0.5 µg/ml PRP, 63%; 1 µg/ml PRP, 74%; and 10 µg/ml PRP, 91% inhibition). Members of the H3K9 family were shown to transcriptionally repress tumor suppressor genes and contribute to cancer progression. Our experimental data indicated that PRP-1 restores tumor suppressor desmosomal protein expression in JJ012 human chondrosarcoma cells and inhibits H3K9 demethylase activity, contributing to the suppression of tumorigenic potential in chondrosarcoma cells.

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Unlike the superficial part of the corneous layer of the epidermis (Stratum corneum) where desmosomes are degraded and corneocytes flake away, the trichocytes in the hair remain attached to each other after cornification. The permanence and fine localization of cell junctions, in particular of desmosomal proteins in the cornifying and mature human hair, is not known. The present electron microscope immunolocalization study indicates that two protein markers for desmosomes such as desmoglein 4 and plakophilins 1 and 3 are still present in mature cortical and cuticle cells. These proteins remain mainly localized in the cornified cytoplasmic side of desmosomal remnants of cortical cells, but also in the delta layer of the extracellular region of the membrane complex. This suggests that the delta layer represents an extensive desmosomal remnant formed between mature cortical cells and in cuticle cells. The endocuticle appears to be the site of accumulation of desmosomal proteins and degraded nuclear material. The cornification of desmosomal junctions in both cortical and cuticle cells likely contributes to stabilize the integrity of the hair shaft.

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