Although KCNQ1 gain-of-function mutations have been described in short QT syndrome [19], to our knowledge there is only one report of a heterozygous KCNQ1 mutation also located within D5 (p.A399S) in a young man with ER and sudden cardiac death, without establishing the causal role of the mutation [20]. Here, KCNQ1 is linked to Familial short QT syndrome.