The current reappraisal portrays a vastly different landscape with only 3 genes (KCNQ1, KCNH2, and SCN5A) causing typical LQTS and another 4 genes (CALM1-3 and TRDN) responsible for rare cases of infantile/pediatric LQTS with atypical features. This evidence concerns the gene CALM1 and familial long QT syndrome.