Thus, mutations in the SCN5A gene, which encodes for the pore-forming α-subunit of the cardiac Na+ channel Nav1.5, result in clinical arrhythmic conditions that include the Brugada syndrome (BrS) (Brugada and Brugada, 1992; Chen et al., 1998) and long QT syndrome 3 (LQT3) (Wang et al., 1995). Here, SCN5A is linked to long QT syndrome 3.