KCNJ2 and familial long QT syndrome: Since the discovery of the first Long QT Syndrome (LQTS)- associated genes; KCNQ1 encoding Kv7.1 (LQT1) (4), KCNH2 encoding Kv11.1 (LQT2) (5), SCN5A encoding Nav1.5 (LQT3) (6) and cardiomyopathy-associated MYH7 gene encoding β-myosin heavy chain (7) in the early 1990s, many other ion channels (e.g., KCNJ2 encoding Kir2.1) and functionally diverse proteins have been implicated in a variety of other clinical phenotypes (see Figure 2A for a list of common ones) (9).