KCNE2 is a regulatory beta subunit that modulates voltage-gated potassium channel complexes, playing critical roles in cardiac and epithelial physiology 1. As a single-span transmembrane protein, KCNE2 associates with various alpha subunits including KCNH2 to form the rapidly activating delayed rectifier potassium current (IKr) essential for cardiac repolarization, and with KCNQ1 in gastric parietal cells where it functions as a constitutively open, voltage-insensitive luminal potassium channel 2. KCNE2 modulates gating kinetics, channel stability, and current amplitude across multiple tissues including the heart, stomach, thyroid, and choroid plexus 3. Pathogenic KCNE2 mutations cause Long QT syndrome type 6 (LQT6), a cardiac channelopathy characterized by QT interval prolongation and sudden cardiac death risk 45. However, recent evidence-based curation classified KCNE2 among genes with limited or disputed evidence for typical LQTS causation 6, though it remains associated with congenital arrhythmia syndromes. Beyond cardiac manifestations, KCNE2 disruption affects multiple organ systems including gastric acid secretion and cerebrospinal fluid generation, reflecting its broad physiological importance 13. Mutations in KCNE2 represent approximately 2% of identified LQTS-causing variants in clinical cohorts 4.