Lamin A/C ( LMNA ) Gene-Related Emery–Dreifuss Muscular Dystrophy Presenting with Junctional Rhythm and Ventricular Arrhythmias in Monozygotic Twins

Emery–Dreifuss muscular dystrophy type 2 (EDMD2), caused by autosomal-dominant lamin A/C gene (LMNA) mutations, is associated with early cardiac involvement and a high risk of malignant ventricular arrhythmias, often preceding overt cardiomyopathy. We describe monozygotic 28-year-old male twins with longstanding limb-girdle–predominant muscular dystrophy. One twin presented with unexplained syncope. Electrocardiography demonstrated junctional rhythm, and ambulatory monitoring revealed non-sustained ventricular tachycardia. Cardiac magnetic resonance imaging showed extensive subendocardial myocardial fibrosis. Whole-exome sequencing confirmed a pathogenic autosomal-dominant LMNA variant. Cardiac evaluation of the asymptomatic twin revealed identical electrical abnormalities. Given the high arrhythmic risk, both patients underwent implantable cardioverter-defibrillator (ICD) implantation. Intraoperative electrograms demonstrated severe atrial cardiomyopathy, prompting singlechamber ICD implantation for secondary and the other for primary prevention of sudden cardiac death. This case highlights the malignant arrhythmic phenotype of LMNA-related EDMD2 and underscores the importance of early genetic diagnosis, family screening, cardiac magnetic resonance imaging, and ICD-based prevention strategies.