SCN5A and cardiomyopathy: Pathogenic variants in several genes associated with cardiomyopathies have been identified in familial AF, including variants in sarcomeric and cell-cell contact genes and others.3 Within the group of ion channel genes, variants leading to dysfunction of the cardiac sodium channel (Nav1.5) are associated with familial AF.3,4 The pore-forming α-subunit of the Nav1.5 is encoded by the SCN5A gene.