KCNH2 and familial long QT syndrome: Nonetheless, the evidence from these studies was deemed sufficient by a consensus document by the Heart Rhythm Society and the European Heart Rhythm Association (HRS/EHRA) on genetic testing for cardiomyopathies and channelopathies to state that comprehensive or targeted (RYR2, KCNQ1, KCNH2, and SCN5A) ion channel genetic testing may be considered in SUD cases to determine the cause of death and facilitate the screening of potentially at-risk relatives, especially when LQTS or CPVT is suspected (class IIb, level of evidence C) [4].