Mutations in the lamin A/C gene seem to be important aetiological factors in familial DCM. Heart disease caused by lamin A/C gene mutations is characterised by conduction system disorders with the need for permanent pacemaker implantations, atrial fibrillation, severe heart failure, and increased risk for sudden cardiac death. We described an asymptomatic 28-year-old man with a R190W lamin A/C gene mutation and mild left ventricular enlargement and near normal left ventricular ejection fraction who suffered from sudden cardiac death during sleeping. His electrocardiogram did not show conduction system disease and the most remarkable finding was a progressive decrease in voltage, which may be a marker of disease progression. The case study's mother had a similar phenotype to this and also had died suddenly. Sudden cardiac death in some lamin A/C gene mutations may occur even before the development of severe left ventricular dysfunction and implantable cardioverter-defibrillator should be early considered.