While the SCN5A-p.Y1977N mutation abolished the Nedd4-2 dependent decrease in INa in HEK293 cells (in line with the predicted Nav1.5 gain-of-function linked to the LQT3 phenotype), mice carrying the homologous Scn5a-p.Y1981N mutation did not show any electrophysiological alterations. This evidence concerns the gene SCN5A and long QT syndrome 3.