RBM20 p.Arg636Cys: A Pathogenic Variant Identified in a Family with Several Cases of Unexpected Sudden Deaths

Dilated Cardiomyopathy (DCM) represents a complex inherited condition frequently associated with premature Sudden Cardiac Death (SCD) and progressive myocardial dysfunction. Prior research has shown that pathogenic variants in specific genes, including LMNA, SCN5A, and FLNC, correlate with significantly elevated arrhythmic risk and adverse clinical outcomes. The RNA-binding motif protein 20 (RBM20) functions as a critical regulator of alternative splicing for several essential sarcomeric proteins, including titin, which maintains cardiac structural integrity. Genetic screening currently assists clinicians in stratifying risk for patients with these hereditary cardiac conditions, yet the specific phenotypic triggers for RBM20-related events remain poorly understood. Existing clinical guidelines lack specific management protocols or clear intervention thresholds for individuals carrying mutations in the RBM20 gene compared to more established genetic markers. This absence of evidence motivated the current investigation into the clinical trajectory and phenotypic expression of families affected by these specific genetic alterations in a specialized setting.

This investigation evaluates the genetic profiles and clinical characteristics of patients diagnosed with Dilated Cardiomyopathy (DCM) who harbor pathogenic variants in the RNA-binding motif protein 20 (RBM20) gene. Researchers sought to determine how these specific mutations influence the phenotypic expression of heart disease and the subsequent risk of lethal arrhythmias within affected families. The study focuses on identifying the correlation between the RBM20 p.Arg636Cys variant and the incidence of unexpected Sudden Cardiac Death (SCD) across multiple generations. Clinicians aimed to provide better data for the management of asymptomatic carriers who may still face significant cardiac risks despite having preserved ventricular function. The work addresses the need for improved risk stratification tools in specialized inherited cardiac condition centers to prevent fatalities in young, seemingly healthy individuals. Understanding the progression toward Atrial Fibrillation (AF) and Heart Failure (HF) in this cohort remained a primary objective for optimizing long-term patient care.

The research team identified all carriers of pathogenic RNA-binding motif protein 20 (RBM20) variants within a single national center specializing in the management of inherited cardiac conditions and sudden death. Forensic autopsies provided essential data regarding the circumstances, physiological states, and post-mortem cardiac morphology of deceased family members who suffered unexpected events. Molecular autopsies allowed for the retrospective genetic analysis of relatives who suffered Sudden Cardiac Death (SCD) by extracting DNA from preserved tissue samples. Family screening protocols utilized targeted genetic sequencing to detect the p.Arg636Cys variant in asymptomatic individuals across a large, multi-generational pedigree. Clinical evaluations included measuring Left Ventricular Ejection Fraction (LVEF) via echocardiography to assess the severity of the Dilated Cardiomyopathy (DCM) phenotype in all identified carriers. Longitudinal tracking of cardiac symptoms and rhythm disturbances helped characterize the progression of Heart Failure (HF) and Atrial Fibrillation (AF) across the entire study population.

The study identified a large family exhibiting inherited Dilated Cardiomyopathy (DCM) caused by the RNA-binding motif protein 20 (RBM20) p.Arg636Cys variant and multiple instances of Sudden Cardiac Death (SCD). A 37-year-old male proband experienced unexpected SCD despite maintaining a normal Left Ventricular Ejection Fraction (LVEF) and only a mild DCM phenotype during previous assessments. Systematic family screening revealed four additional asymptomatic carriers who displayed concealed mild DCM phenotypes that were not immediately apparent through standard diagnostic procedures. Historical records and molecular evidence confirmed that six other relatives, including two obligate carriers, died suddenly at young ages due to suspected cardiac arrest. The data demonstrated that the RBM20 p.Arg636Cys mutation leads to high rates of SCD even in the absence of severe structural heart disease or reduced systolic function. Observations indicated a frequent development of Atrial Fibrillation (AF) and progressive Heart Failure (HF) among the surviving variant carriers, necessitating close clinical monitoring.

The RNA-binding motif protein 20 (RBM20) p.Arg636Cys variant represents a highly pathogenic mutation associated with significant risks of Sudden Cardiac Death (SCD) in families with Dilated Cardiomyopathy (DCM). Clinicians should carefully evaluate the early implantation of an Implantable Cardioverter-Defibrillator (ICD) for all individuals carrying this specific genetic variant to prevent fatal outcomes. The presence of a mild Dilated Cardiomyopathy (DCM) phenotype does not preclude the risk of lethal arrhythmic events, suggesting that structural severity is a poor predictor of SCD. Medical teams must maintain high awareness regarding the potential for rapid Heart Failure (HF) progression and the early onset of Atrial Fibrillation (AF) in these patients. Future management strategies for RBM20 carriers may require more aggressive intervention and frequent surveillance than current standard DCM protocols suggest for the general population. Enhanced genetic surveillance and molecular autopsy of at-risk relatives remain essential for identifying concealed carriers and preventing further unexpected fatalities within these affected pedigrees.