Although CACNA1C retained a definitive classification for the disease entity of Timothy Syndrome, a specific amino acid position (p.Arg518Cys/His) is reported in association with an isolated cardiac phenotype of LQTS/HCM;39 however, current evidence is lacking to confidently split this disease entity from Timothy Syndrome, but will be considered in future. Here, CACNA1C is linked to familial long QT syndrome.