Objectives This study aimed to identify the genetic defect in a family with idiopathic ventricular fibrillation (IVF) manifesting in childhood and adolescence. Background Although sudden cardiac ...death in the young is rare, it frequently presents as the first clinical manifestation of an underlying inherited arrhythmia syndrome. Gene discovery for IVF is important as it enables the identification of individuals at risk, because except for arrhythmia, IVF does not manifest with identifiable clinical abnormalities. Methods Exome sequencing was carried out on 2 family members who were both successfully resuscitated from a cardiac arrest. Results We characterized a family presenting with a history of ventricular fibrillation (VF) and sudden death without electrocardiographic or echocardiographic abnormalities at rest. Two siblings died suddenly at the ages of 9 and 10 years, and another 2 were resuscitated from out-of-hospital cardiac arrest with documented VF at ages 10 and 16 years, respectively. Exome sequencing identified a missense mutation affecting a highly conserved residue (p.F90L) in the CALM1 gene encoding calmodulin. This mutation was also carried by 1 of the siblings who died suddenly, from whom DNA was available. The mutation was present in the mother and in another sibling, both asymptomatic but displaying a marginally prolonged QT interval during exercise. Conclusions We identified a mutation in CALM1 underlying IVF manifesting in childhood and adolescence. The causality of the mutation is supported by previous studies demonstrating that F90 mediates the direct interaction of CaM with target peptides. Our approach highlights the utility of exome sequencing in uncovering the genetic defect even in families with a small number of affected individuals.
Desmin-related myopathy is a clinically heterogenous group of disorders encompassing myopathies, cardiomyopathies, conduction disease, and combinations of these disorders. Mutations in the gene ...encoding desmin (DES), a major intermediate filament protein, can underlie this phenotype.
The purpose of this study was to investigate the clinical and pathologic characteristics of 27 patients from five families with an identical mutation in the head domain region (p.S13F) of desmin.
All 27 carriers or obligate carriers of a p.S13F DES founder mutation demonstrated a fully penetrant yet variable phenotype. All patients demonstrated cardiac involvement characterized by high-grade AV block at young ages and important right ventricular (RV) involvement. RV predominance was demonstrated by the presence of right bundle branch block in 10 patients (sometimes as a first manifestation) and by RV heart failure in 6 patients, including 2 patients who fulfilled the diagnostic criteria for arrhythmogenic RV cardiomyopathy. Because of this clinical overlap with desmosome cardiomyopathies, we also studied the organization of the intercalated disks, particularly the distribution of desmosomal proteins. Normal amounts of the major desmosomal proteins were found, but the intercalated disks were more convoluted and elongated and had a zigzag appearance.
In this largest series to date of individuals with a single head domain DES mutation, patients show a variable yet predominantly cardiologic phenotype characterized by conduction disease at an early age and RV involvement including right bundle branch block and/or RV tachycardias and arrhythmogenic RV cardiomyopathy phenocopies. A localized effect of desmin on the structure of the cardiac intercalated disks might contribute to disease pathogenesis.
Abstract Background The multifactorial pathogenesis leading to dilated cardiomyopathy (DCM) makes stratification difficult. The recent MOGE(S) (morphofunctional, organ involvement, genetic or ...familial, etiology, stage) classification addresses this issue. Objectives The purpose of this study was to investigate the applicability and prognostic relevance of the MOGE(S) classification in patients with DCM. Methods This study used patients from the Maastricht Cardiomyopathy Registry in the Netherlands and excluded patients with ischemic, valvular, hypertensive, and congenital heart disease. All other patients underwent a complete diagnostic work-up, including genetic evaluation and endomyocardial biopsy. Results A total of 213 consecutive patients with DCM were included: organ involvement was demonstrated in 35 (16%) and genetic or familial DCM in 70 (33%) patients, including 16 (8%) patients with a pathogenic mutation. At least 1 cause was found in 155 (73%) patients, of whom 48 (23%) had more than 1 possible cause. Left ventricular reverse remodeling was more common in patients with nongenetic or nonfamilial DCM than in patients with genetic or familial DCM (40% vs. 25%; p = 0.04). After a median follow-up of 47 months, organ involvement and higher New York Heart Association functional class were associated with adverse outcome (p < 0.001 and p = 0.02, respectively). Genetic or familial DCM per se was of no prognostic significance, but when it was accompanied by additional etiologic-environmental factors such as significant viral load, immune-mediated factors, rhythm disturbances, or toxic triggers, a worse outcome was revealed (p = 0.03). A higher presence of MOGE(S) attributes (≥2 vs. ≤1 attributes) showed an adverse outcome (p = 0.007). Conclusions The MOGE(S) classification in DCM is applicable, and each attribute or the gene-environment interaction is associated with outcome. Importantly, the presence of multiple attributes was a strong predictor of adverse outcome. Finally, adaptation of the MOGE(S) involving multiple possible etiologies is recommended.
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