KCNQ1 and channelopathy: Regarding the etiology of channelopathies such as the Congenital Long QT Syndromes itself, 75% of LQTS cases are linked to mutations in genes encoding for voltage-gated potassium channel subunits (KCNQ1, KCNH2, KCNE1, KCNE2), or for voltage-gated sodium channel SCN5A.