Recessive variants in plakophilin-2 contributes to early-onset arrhythmogenic cardiomyopathy with severe heart failure

Natural History and Clinical Outcomes of Patients With DSG2/DSC2 Variant-Related Arrhythmogenic Right Ventricular Cardiomyopathy

BACKGROUND

Genetic variants in desmosomal cadherins, desmoglein 2 (DSG2) and desmocollin 2 (DSC2), cause a distinct form of arrhythmogenic right ventricular cardiomyopathy (ARVC), which remains poorly reported. In this study, we aimed to provide a comprehensive description of the phenotypic expression, natural history, and clinical outcomes of patients with this ARVC subset.

METHODS

Genetic and clinical data of DSG2 and DSC2 variant carriers were collected from 5 countries in Europe and Asia. We assessed the phenotypic profile of these patients and their clinical outcomes, focusing on heart failure and ventricular arrhythmia events.

RESULTS

Overall, 271 subjects, 254 with DSG2 variants, were included in this study (median age, 38 years [interquartile range, 25-52]; 62.7% male). Of these, 165 were probands, and 200 were diagnosed with definite ARVC. A total of 181 (66.8%) individuals carried missense variants, mainly distributed in the extracellular domains. Notably, we included 78 (28.8%) individuals with multiple variants. Of the 200 cases with diagnosed ARVC, 41 (20.5%) experienced premature cardiac death before the age of 65. Among the 81 individuals for whom both left ventricular ejection fraction and right ventricular fractional area change data were available at presentation, 29 (35.8%) had isolated right ventricular dysfunction, and 16 (19.8%) had biventricular dysfunction. Single-variant carriers who engaged in intense physical exercise were younger at disease onset compared with those who did not (P=0.001). Compared with single-variant carriers, those with multiple variants were more likely to be diagnosed with ARVC (96.2% versus 64.8%; P<0.001) and exhibited more severe left ventricular dysfunction (44.4% versus 22.1%; P=0.001) and right ventricular dilation (88.9% versus 55.8%, P<0.001). Multiple-variant carriers were significantly younger at ARVC diagnosis compared with single-variant carriers (33 [18-49] years versus 42 [27-54] years; P<0.001]. During follow-up, end-stage heart failure (P<0.001) and malignant ventricular arrhythmias (P=0.004) were significantly more frequent in multiple-variant compared with single-variant carriers. Compared with PKP2 patients, DSG2/DSC2 patients exhibited a significantly higher risk of end-stage heart failure (P<0.001).

CONCLUSIONS

ARVC attributable to variants in desmosomal cadherins mostly present with right ventricular or biventricular disease. Multiple variants are common in these patients and are associated with more frequent clinical penetrance, earlier onset of disease, and adverse clinical outcomes.

A Heterozygous Phospholamban Variant (p.R14del) Leads to Left Ventricular Involvement and Heart Failure Phenotypes in Arrhythmogenic Right Ventricular Cardiomyopathy

This study aimed to determine the prevalence and clinical features of Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) caused by pathogenic mutations in the Phospholamban (PLN) gene. The study included 170 patients who had a confirmed diagnosis of ARVC and underwent PLN genetic screening using next-generation sequencing. The findings of this study provide valuable insights into the association between PLN mutations and ARVC, which can aid in the development of more effective diagnostic and treatment strategies for ARVC patients. Out of the patients evaluated, six had a rare pathogenic mutation in PLN with the same p.R14del variant. Family screening revealed that heterozygous carriers of p.R14del exhibited a definite ARVC phenotype. In clinical studies, individuals with the p.R14del mutation experienced a similar rate of malignant arrhythmia events as those with classic desmosome mutations. After adjusting for covariates, individuals with PLN mutations had a two point one seven times greater likelihood of experiencing transplant-related risks compared to those who did not possess PLN mutations (95% CI 1.08-6.82, p = 0.035). The accumulation of left ventricular fat and fibers is a pathological marker for ARVC patients with p.R14del mutations. In a cohort of 170 Chinese ARVC patients, three point five percent of probands had the PLN pathogenic variant (p.R14del) and all were female. Our data shows that PLN-related ARVC patients are at high risk for ventricular arrhythmias and heart failure, which requires clinical differentiation from classic ARVC. Furthermore, carrying the p.R14del mutation can be an independent prognostic risk factor in ARVC patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00126-w.

Disease modeling of desmosome-related cardiomyopathy using induced pluripotent stem cell-derived cardiomyocytes

Cardiomyopathy is a pathological condition characterized by cardiac pump failure due to myocardial dysfunction and the major cause of advanced heart failure requiring heart transplantation. Although optimized medical therapies have been developed for heart failure during the last few decades, some patients with cardiomyopathy exhibit advanced heart failure and are refractory to medical therapies. Desmosome, which is a dynamic cell-to-cell junctional component, maintains the structural integrity of heart tissues. Genetic mutations in desmosomal genes cause arrhythmogenic cardiomyopathy (AC), a rare inheritable disease, and predispose patients to sudden cardiac death and heart failure. Recent advances in sequencing technologies have elucidated the genetic basis of cardiomyopathies and revealed that desmosome-related cardiomyopathy is concealed in broad cardiomyopathies. Among desmosomal genes, mutations in PKP2 (which encodes PKP2) are most frequently identified in patients with AC. PKP2 deficiency causes various pathological cardiac phenotypes. Human cardiomyocytes differentiated from patient-derived induced pluripotent stem cells (iPSCs) in combination with genome editing, which allows the precise arrangement of the targeted genome, are powerful experimental tools for studying disease. This review summarizes the current issues associated with practical medicine for advanced heart failure and the recent advances in disease modeling using iPSC-derived cardiomyocytes targeting desmosome-related cardiomyopathy caused by PKP2 deficiency.

Validation of an Arrhythmogenic Right Ventricular Cardiomyopathy Risk-Prediction Model in a Chinese Cohort

Background: The novel arrhythmogenic right ventricular cardiomyopathy (ARVC)-associated ventricular arrhythmias (VAs) risk-prediction model endorsed by Cadrin-Tourigny et al. was recently developed to estimate visual VA risk and was identified to be more effective for predicting ventricular events than the International Task Force Consensus (ITFC) criteria, and the Heart Rhythm Society (HRS) criteria. Data regarding its application in Asians are lacking. Objectives: We aimed to perform an external validation of this algorithm in the Chinese ARVC population. Methods: The study enrolled 88 ARVC patients who received implantable cardioverter-defibrillator (ICD) from January 2005 to January 2020. The primary endpoint was appropriate ICD therapies. The novel prediction model was used to calculate a priori predicted VA risk that was compared with the observed rates. Results: During a median follow-up of 3.9 years, 57 (64.8%) patients received the ICD therapy. Patients with implanted ICDs for primary prevention had non-significantly lower rates of ICD therapy than secondary prevention (5-year event rate: 0.46 (0.13–0.66) and 0.80 (0.64–0.89); log-rank p = 0.098). The validation study revealed the C-statistic of 0.833 (95% confidence interval (CI) 0.615–1.000), and the predicted and the observed patterns were similar in primary prevention patients (mean predicted–observed risk: −0.07 (95% CI −0.21, 0.09)). However, in secondary prevention patients, the C-statistic was 0.640 (95% CI 0.510–0.770) and the predicted risk was significantly underestimated (mean predicted–observed risk: −0.32 (95% CI −0.39, −0.24)). The recalibration analysis showed that the performance of the prediction model in secondary prevention patients was improved, with the mean predicted–observed risk of −0.04 (95% CI −0.10, 0.03). Conclusions: The novel risk-prediction model had a good fitness to predict arrhythmic risk in Asian ARVC patients for primary prevention, and for secondary prevention patients after recalibration of the baseline risk.

Modeling reduced contractility and impaired desmosome assembly due to plakophilin-2 deficiency using isogenic iPS cell-derived cardiomyocytes

Loss-of-function mutations in PKP2, which encodes plakophilin-2, cause arrhythmogenic cardiomyopathy (AC). Restoration of deficient molecules can serve as upstream therapy, thereby requiring a human model that recapitulates disease pathology and provides distinct readouts in phenotypic analysis for proof of concept for gene replacement therapy. Here, we generated isogenic induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) with precisely adjusted expression of plakophilin-2 from a patient with AC carrying a heterozygous frameshift PKP2 mutation. After monolayer differentiation, plakophilin-2 deficiency led to reduced contractility, disrupted intercalated disc structures, and impaired desmosome assembly in iPSC-CMs. Allele-specific fluorescent labeling of endogenous DSG2 encoding desmoglein-2 in the generated isogenic lines enabled real-time desmosome-imaging under an adjusted dose of plakophilin-2. Adeno-associated virus-mediated gene replacement of PKP2 recovered contractility and restored desmosome assembly, which was sequentially captured by desmosome-imaging in plakophilin-2-deficient iPSC-CMs. Our isogenic set of iPSC-CMs recapitulates AC pathology and provides a rapid and convenient cellular platform for therapeutic development.

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Generation of isogenic iPSC-CMs with a precise dose of plakophilin-2

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Modeling reduced contractility and impaired desmosome assembly using iPSC-CMs

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Generation of isogenic iPSC-CMs for desmosome-imaging

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Proof of concept of PKP2 replacement using isogenic plakophilin-2-deficient iPSC-CMs

Arrhythmogenic Right Ventricular Cardiomyopathy in Pediatric Patients: An Important but Underrecognized Clinical Entity

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by fibrofatty infiltration of predominantly the right ventricular (RV) myocardium. Affected patients typically present as young adults with hemodynamically stable ventricular tachycardia, although pediatric cases are increasingly recognized. These young subjects often have a more severe phenotype with a high risk of sudden cardiac death (SCD) and progression toward heart failure. Diagnosis of ARVC is made by combining multiple sources of information as prescribed by the consensus-based Task Force Criteria. The description of Naxos disease, a fully penetrant autosomal recessive disorder that is associated with ARVC and a cutaneous phenotype of palmoplantar keratoderma and wooly hair facilitated the identification of the genetic cause of ARVC. At present, approximately 60% of patients are found to carry a pathogenic variant in one of five genes associated with the cardiac desmosome. The incomplete penetrance and variable expressivity of these variants however implies an important role for environmental factors, of which participation in endurance exercise is a strong risk factor. Since there currently is no definite cure for ARVC, disease management is directed toward symptom reduction, delay of disease progression, and prevention of SCD. This clinically focused review describes the spectrum of ARVC among children and adolescents, the genetic architecture underlying this disease, the cardio-cutaneous syndromes that led to its identification, and current diagnostic and therapeutic strategies in pediatric ARVC subjects.

Cardiomyopathies in China: A 2018-2019 state-of-the-art review

Cardiomyopathies are diseases of the cardiac muscle and are often characterized by ventricular dilation, hypertrophy, and cardiac arrhythmia. Patients with cardiomyopathies often experience sudden death and cardiac failure and require cardiac transplantation during the course of disease progression. Early diagnosis, differential diagnosis, and genetic consultation depend on imaging techniques, genetic testing, and new emerging diagnostic tools such as serum biomarkers. The molecular genetics of cardiomyopathies has been widely studied recently. The discovery of mechanisms underlying heterogeneity and overlapping of the phenotypes of cardiomyopathies has revealed the existence of disease modifiers, and this has led to the emergence of novel disease-modifying therapy. This 2018-2019 state-of-the-art review outlines the pathogenesis, diagnosis, and treatment of cardiomyopathies in China.