For the compiled mutations extracted from the literature, we searched Entrez PubMed (http://www.ncbi.nlm.nih.gov/sites/entrez) using “Long QT syndrome”, “Sudden unexplained cardiac death”, and the names and abbreviations of genes published as related to LQTS (KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, KCNJ2, AKAP9, ANK2, CACNA1C, SCNA4B, SNTA1, and CAV3) as key words. Here, KCNJ2 is linked to familial long QT syndrome.