For example, a blockage ofthe hERG potassium ion channels by the evaluated drugs could resultin the induction of lethal cardiac arrhythmias.41 Furthermore, in the case of the hepatic cytochrome P450enzymes, these are a polymorphic multigene enzyme family that playa role in the metabolism of drugs, steroids, and other compounds.42 The gene discussed is KCNH2; the disease is cardiac rhythm disease.