Loss-of-function mutations in KCNQ1 are linked to an increase in AP duration associated with long QT-syndrome type I, whereas gain-of-function mutations in KCNQ1 are associated with short QT-syndrome (SQT2) (Brenyo et al., 2012) and familial AF (Chen et al., 2003). This evidence concerns the gene KCNQ1 and Familial short QT syndrome.