KCNA3 encodes Kv1.3, a voltage-gated potassium channel critical for immune cell function and neuronal signaling. Despite UniProt annotation suggesting absent channel activity, functional studies demonstrate KCNA3 mediates potassium ion transport and delayed rectifier potassium channel activity 1. JAK2 signaling upregulates KCNA3 channel activity and membrane abundance, linking it to interferon-γ-regulated lymphocyte function 2. De novo heterozygous missense variants in KCNA3 cause developmental and epileptic encephalopathies (DEE), with 86% of carriers presenting severe neurological phenotypes including intellectual disability, epilepsy, and autism spectrum disorder 1. Functional analysis reveals heterogeneous effects ranging from loss-of-function (altered inactivation kinetics, depolarized activation threshold) to mixed loss- and gain-of-function properties 13. The antidepressant fluoxetine shows potential therapeutic benefit for gain-of-function variants 1. Beyond neurology, KCNA3 hypermethylation serves as a biomarker for esophageal cancer detection. A dual-marker blood test targeting methylated KCNA3 and OTOP2 achieves 87.4% sensitivity and 93.3% specificity for esophageal cancer detection with excellent stage-stratified performance 45. KCNA3 also associates with autoimmune pancreatitis susceptibility in genome-wide studies 6.