Reduction of CDI was observed for several LQTS-causing CaM mutations, including D132H, D132V, and E141G (Boczek et al., 2016; Pipilas et al., 2016), whereas CDI was completely absent for LQTS-associated CaM mutations D96V, D130G, and F142L in HEK293 cells and adult guinea pig cardiomyocytes (Limpitikul et al., 2014). Here, CALM2 is linked to familial long QT syndrome.