GJA1 and cardiac rhythm disease: Homozygous Cx43(K258stop) mice are not viable due to severe edema, attributed to loss of the epithelial junctional barrier10; mice heterozygous for truncated Cx43 (Cx43K258/−) show defective migration of neuronal precursors11, altered intercalated disc structure and localization12 and predisposition to cardiac arrhythmias and larger infarct size after cardiac or cerebral ischemia13,14.