KCND2 encodes Kv4.2, a voltage-gated potassium channel that mediates A-type potassium currents in neurons and cardiac cells 1. In the brain, KCND2 conducts the dendritic A-type current (I_SA), regulating neuronal excitability, action potential firing frequency, and back-propagation [UniProt]. The channel functions as a tetrameric complex, with surface expression and kinetics modulated by regulatory subunits including KCNIP family members [UniProt]. KCND2 plays roles in circadian rhythm regulation and pain signaling via metabotropic glutamate receptor pathways [UniProt]. Mutations in KCND2 are associated with genetic epilepsy, representing a significant research focus for precision therapy 2. KCND2 expression at the cancer-neuron interface in glioblastoma enhances neuronal excitability through extracellular potassium accumulation, linking the channel to seizure development in brain tumors 3. In breast cancer, elevated KCND2 expression correlates with reduced survival and promotes cell proliferation, migration, and G1/S phase transition 45. Conversely, KCND2 mutations do not frequently cause long QT syndrome, despite theoretical cardiac involvement 6. These findings establish KCND2 as both a critical regulator of neuronal excitability and an emerging oncogenic factor in multiple cancer types.