At the perinexus, Cx43 HCs interact with Nav1.5 (SCN5A), the pore-forming subunit of the voltage-gated Na+ channel that is essential for cardiomyocyte depolarization, and Kir2.1 K+ channels, associated with Andersen-Tawil syndrome and short QT syndrome (104–106). Here, SCN5A is linked to short QT syndrome.