Of the 17 genes reported as causative for LQTS, nine genes (AKAP9, ANK2, CAV3, KCNE1, KCNE2, KCNJ2, KCNJ5, SCN4B, SNTA1) were classified as having limited or disputed evidence as LQTS-causative genes. This evidence concerns the gene SCN4B and familial long QT syndrome.