Brugada Syndrome Associated with Different Heterozygous SCN5A Variants in Two Unrelated Families

The cardiac sodium channel (Nav1.5) controls cardiac excitability by triggering the action potential of cardiac myocytes and controlling electric impulse transmission. However, it has also been associated with arrhythmogenic cardiomyopathies. Accordingly, genetic variants in SCN5A that result in loss of function of Nav1.5 are associated with inherited arrhythmia syndromes, which are caused by reduced cardiac excitability, particularly Brugada syndrome (BrS) as well as arrhythmogenic right ventricular cardiomyopathy (ARVC). We report a novel pathogenic SCNA5 variant being associated with BrS overlapping with ARVC, as well as disease progression with a previously reported SCN5A variant being associated with a phenotype of BrS and conduction system disorder in two unrelated families. Keywords: Brugada syndrome; SCN5A; arrhythmogenic right ventricular cardiomyopathy; channelopathy; overlapping syndrome