SCN5A and cardiac arrhythmia: In addition, we found down-regulation of sodium (Na+) and potassium (K+) ion channel encoding genes, such as KCNQ1, KCNK3, KCNN2, KCNH2, SCN2B and SCN5A. Deregulated Na+ and K+ ion channels play an important role in cardiac arrhythmias and heart failure (Remme and Bezzina 2010; Nabauer and Kaab 1998).