SCN5A and cardiac arrhythmia: Several inherited Nav channelopathies are caused by LoF mutations such as Brugada syndrome, a cardiac arrhythmia due in part to Nav1.5 gating defects, and Dravet syndrome, a severe and lifelong form of pediatric epilepsy due to Nav1.1 haploinsufficiency (Loussouarn et al., 2015; Mantegazza et al., 2021).