Desmoplakin (DP) is an essential component of the desmosomal adhesion complex, tethering intermediate filaments to sites of intercellular adhesion to confer mechanical integrity to tissues. As a frequent target for mutation in cardiocutaneous syndromes that vary widely in phenotype, DP's roles as a signaling hub are rapidly emerging. Here, we identify the RhoGEF Ect2 as a previously unappreciated component of intercellular junctions in close association with DP. DP promotes the localization of Ect2 to keratinocyte desmosomes and cardiac intercalated discs, where it maintains active RhoA (Rho-GTP) at the membrane. We demonstrate that Ect2 activity is regulated by PKC in a DP-dependent manner in cardiac myocytes. Finally, a truncated form of DP expressed in patients with Carvajal syndrome associated with severe cardiocutaneous defects is impaired in its ability to bind and localize Ect2 to cell junctions in cardiomyocytes and patient keratinocytes. Our findings delineate an important relationship between a component of the desmosome and a critical regulator of actin cytoskeletal remodeling that could have widespread implications for understanding cardiac and cutaneous health and disease pathogenesis.

The NAXCARE (NAXos disease and Cardiocutaneous Assessment and Registry for Evaluation) is a global initiative designed to collect, store, and analyze clinical outcomes data on patients with Naxos disease and related cardiocutaneous syndromes (CCS). This registry aims to fill the gaps in clinical knowledge, enhance treatment approaches, and improve patient outcomes by systematically documenting disease progression, genetic profiles, and patient care pathways. The following methodology outlines the registry's design, data collection protocols, management, security measures, and anticipated contributions to research and clinical practice.

In this case report, we aimed to raise awareness regarding arrhythmogenic cardiomyopathy (ACM) with inflammatory "hot phase" episodes in pediatric patients, which is often misdiagnosed as myocarditis. This condition, caused by aseptic intracellular inflammation, can be misdiagnosed as acute coronary syndrome or myocardial viral infection, with the latter being particularly common in children. Here, we report two pediatric cases of ACM with "hot phase" episodes and discuss the molecular mechanisms leading to aseptic myocardial inflammation due to desmosome and cytoskeletal damage. The first patient (aged 13 years) was hospitalized after experiencing a single episode of syncope, chest pain, and palpitation. Clinical examination revealed elevated troponin levels, complete right bundle branch block, right ventricular dilation, and normal coronary arteries. Cardiac magnetic resonance imaging (MRI) revealed extensive fibrotic changes in the right ventricle, which was consistent with ACM, and a pathogenic variant in DSG2 confirmed the diagnosis. The second patient (aged 4 years) presented with chest pain and elevated troponin levels. Electrocardiography revealed a left bundle branch block, while echocardiography showed reduced left ventricular contractility. Cardiac MRI demonstrated left ventricular dilation and subepicardial fibrosis. The phenotypic features, such as curly-wool hair, hyperkeratosis, and onychodystrophy, suggested a genetic nature of the disease. Two mutations identified in DSP confirmed the diagnosis of Carvajal syndrome with intermittent "hot phase" episodes. ACM in children can present with nonspecific inflammatory symptoms, which may be misdiagnosed as myocarditis or coronary artery pathology.

Naxos disease variant (Carvajal syndrome) is a cardiocutaneous genetic disease caused by Plakoglobin and Desmoplakin gene mutation, and usually manifests with woolly hair, palmoplantar keratoderma, and cardiomyopathy, and are found to have a high risk for uncontrolled arrhythmia. An observational retrospective cohort study was conducted at King Faisal Specialist Hospital & Research Center in Riyadh, Saudi Arabia, a tertiary care hospital, which included 10 Saudi pediatric patients with clinical manifestations that indicate Naxos disease variant. The medical records of the patients were analyzed such as Echocardiography parameters (for ventricular function assessment), electrocardiography (ECG), 24-h Holter (for arrhythmias), and genetic analysis results were collected to confirm the medical diagnosis. We report 10 Saudi pediatric patients with Naxos disease variant who presented with severe dilated cardiomyopathy manifestation. All the patients had woolly hair, and half had palmoplantar keratoderma. They all had severely dilated and depressed left ventricular systolic function, and nine of them also had depressed right ventricular systolic function. Frequent premature ventricular tachycardias (PVCs) were reported in nine cases, and an implantable cardioverter defibrillator (ICD) was implanted in 3 patients for uncontrolled ventricular tachycardias. Moreover, four patients underwent heart transplantation, and three died suddenly while waiting for a heart donation. Finally, in 8 patients, genetic studies were homozygous for Desmoplakin gene (DSP), confirming the diagnosis. Naxos disease variant is accompanied by high risk of arrhythmia and sudden cardiac deaths, so family members of proband need an extensive genetic workup for identification of gene carriers for counseling, especially in our Arab countries where consanguineous marriage is common. Moreover, hair and skin phenotypes in a child should alert for signs of cardiomyopathy manifestation.