Variant V351E (2 residues upstream of the Timothy syndrome mutations in CACNA1C) is located in exactly the same position as mutation V401L (Figure 3), which causes a pronounced type 2 gating change in Cav1.3 and is associated with a severe neurodevelopmental phenotype (Ortner and Striessnig, 2020). Here, CACNA1D is linked to Timothy syndrome.