Ion channel dysfunction remains one of the crucial factors in VT initiation, and in most cases of acquired arrhythmias, IKr remains the dominant channel of clinical cardiotoxicity concern; and the FDA and European Medicines Agency requires screening against the human ether-à-go-go-related gene (hERG) for all new drugs being evaluated [38,39]. The gene discussed is KCNH2; the disease is cardiac arrhythmia.