Development Of Arrhythmogenic Right Ventricular Cardiomyopathy Research Articles

Whole-Exome Sequencing Identifies a Novel Mutation of Desmocollin 2 in a Chinese Family With Arrhythmogenic Right Ventricular Cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare heart disorder characterized by myocyte loss and fibro-fatty tissue replacement. With the progress of ARVC, patient can present serious ventricular arrhythmias, heart failure, and even sudden cardiac death. Previous studies have revealed that the generation and development of ARVC are related to structural changes of desmosomes. To date, at least 5 genes associated with desmosomes have been identified in patients with ARVC, including Desmoplakin, Plakophilin 2, Desmoglein 2, Desmocollin 2, and Junction plakoglobin. In this study, we applied whole-exome sequencing to explore the potential causative gene in a Chinese family with suspicious ARVC. A novel missense mutation (c.1090G > A/p.V364M) of DSC2 was identified and co-segregated with the affected family members. This mutation leads to a substitution of valine by methionine and is predicted to be damaging by bioinformatics tools. In conclusion, our study not only expands the spectrum of DSC2 mutations and contributes to genetic counseling of families with ARVC but also improves the awareness of pathogenesis in Chinese patients with ARVC.

Abstract 164: β-adrenergic Stimulation Exacerbates Preclinical Arrhythmogenic Right Ventricular Cardiomyopathy Due To Desmoplakin Mutation

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with ventricular arrhythmias and sudden cardiac death. We previously demonstrated that cardiac-specific overexpression of human mutant desmoplakin (DSPR2834H) leads to ARVC in mice at 6 months of age. However, the potential role and mechanism(s) of DSP in preclinical ARVC under cardiac stress remains unclear. Objectives: This study is aimed to elucidate the impact of DSP in the development of ARVC under adrenergic stimulation. Methods: Three-month-old non-transgenic (NTg), wild-type DSP (Tg-DSPWT) and Tg-DSPR2834H mice without obvious signs of ARVC, including right and left ventricular dysfunction, arrhythmias, were infused with either vehicle or isoproterenol (30mg/kg/d) for 2 weeks using mini-osmotic pumps. During isoproterenol infusion, electrocardiography (ECG) was monitored daily on conscious mice. Echocardiography and cardiac MRI were performed before and after 2-week of isoproterenol infusion. Myocardial tissues from both RV and LV were subjected to cellular, biochemical and histopathological analysis. Results: Isoproterenol resulted in cardiac hypertrophy to a similar degree amongst all genotypes; however, mortality occurred only in Tg-DSPR2834H mice. Vehicle-treated mice from all genotypes showed largely normal ECGs, whereas isoproterenol led to various types of arrhythmia in Tg-DSPR2834H mice including ventricular tachycardia and QT prolongation. Echocardiography analysis revealed LV dysfunction (decreased factional shortening) in isoproterenol-treated Tg-DSPR2834H mice compared to other treatment groups. Interstitial fibrosis and lipid infiltration was prominent in the Tg-DSPR2834H myocardium. MRI analysis is being performed to understand the RV and LV geometry and function. Conclusion: Our preliminary data confirms the essential role of desmoplakin in response to adrenergic stimulation. Studies investigating the electrophysiological, geometrical and cellular mechanisms of the pro-arrhythmic nature of DSPR2834H dysfunction are ongoing which may ultimately provide critical experimental data on prevention of asymptomatic preclinical ARVC in humans.

Desmosomal gene evaluation in Boxers with arrhythmogenic right ventricular cardiomyopathy

To sequence the exonic and splice site regions of the 4 desmosomal genes associated with the human form of familial arrhythmogenic right ventricular cardiomyopathy (ARVC) in Boxers with ARVC and identify a causative mutation. 10 unrelated Boxers with ARVC and 2 unaffected Labrador Retrievers (control dogs). Exonic and splice site regions of the 4 genes encoding the desmosomal proteins plakophilin-2, plakoglobin, desmoplakin, and desmoglein-2 were sequenced. Sequences were compared for nucleotide sequence changes between affected dogs and the published sequences for clinically normal dogs and between affected dogs and the control dogs. Base-pair changes were considered to be causative for ARVC if they were detected in an affected dog but not in unaffected dogs, and if they involved a conserved amino acid and changed that amino acid to one of a different polarity, acid-base status, or structure. A causative mutation for ARVC in Boxers was not identified, although single nucleotide polymorphisms were detected in some affected dogs within exon 3 of the plakophilin-2 gene; exon 3 of the plakoglobin gene; exons 3 and 7 of the desmoglein-2 gene; and exons 6, 14, 15, and 24 of the desmoplakin gene. None of these changed the amino acid of the respective protein. Mutations within the desmosomal genes associated with the development of ARVC in humans do not appear to be causative for ARVC in Boxers. Genomewide scanning for genetic loci of interest in dogs should be pursued.

Age- and Training-Dependent Development of Arrhythmogenic Right Ventricular Cardiomyopathy in Heterozygous Plakoglobin-Deficient Mice

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disorder that causes sudden death and right ventricular heart failure in the young. Clinical data suggest that competitive sports may provoke ARVC in susceptible persons. Genetically, loss-of-function mutations in desmosomal proteins (plakophilin, desmoplakin, or plakoglobin) have been associated with ARVC. To test the hypothesis that reduced desmosomal protein expression causes ARVC, we studied the cardiac effects of heterozygous plakoglobin deficiency in mice. Ten-month-old heterozygous plakoglobin-deficient mice (plakoglobin+/-) had increased right ventricular volume, reduced right ventricular function, and spontaneous ventricular ectopy (all P<0.05). Left ventricular size and function were not altered. Isolated, perfused plakoglobin+/- hearts had spontaneous ventricular tachycardia of right ventricular origin and prolonged right ventricular conduction times compared with wild-type hearts. Endurance training accelerated the development of right ventricular dysfunction and arrhythmias in plakoglobin+/- mice. Histology and electron microscopy did not identify right ventricular abnormalities in affected animals. Heterozygous plakoglobin deficiency provokes ARVC. Manifestation of the phenotype is accelerated by endurance training. This suggests a functional role for plakoglobin and training in the development of ARVC.