Since the release of ICH S7 guidelines mandating in vitro hERG patch clamp and in vivo nonrodent telemetry for the assessment of proarrhythmia before first-in-human studies for investigational drugs, the rate of serious arrhythmia reported in phase I clinical trials has fallen by ∼70% from 2000 to 2021 (Fig. S1A). The gene discussed is KCNH2; the disease is Arrhythmia.