KCNH8 encodes a voltage-gated potassium channel that functions as the pore-forming subunit of a delayed rectifier channel mediating outward-rectifying potassium currents. The channel exhibits slowly activating, non-inactivating kinetics and opens at hyperpolarized potentials (half-maximal activation at approximately -62 mV), with activation strongly dependent on external pH 1. KCNH8 is primarily expressed in the nervous system, where it can form heteromultimers with other Elk family members but not with Eag, Erg, or conventional Kv channels 1. Genetic variants in KCNH8 associate with multiple disease states and physiological traits. A genome-wide association study identified KCNH8 as a susceptibility locus for chr3 venous disease 2, while variants are also associated with VO₂max training response and elite athletic performance in endurance sports 3, 4. In cancer contexts, KCNH8 appears dysregulated in peripheral T cell lymphoma and prostate cancer with ETS rearrangements 5, 6, and KCNH8 was identified as a marker associated with radiotherapy resistance in rectal cancer 7. Recent studies further link rare KCNH8 variants to eczema susceptibility 8. Given the channel's role in regulating membrane potential, KCNH8 represents a potential therapeutic target for conditions involving abnormal neuronal or cardiac excitability. Potassium channel modifiers including 3,4-diaminopyridine (dalfampridine) and amifampridine are established treatments for disorders of neuromuscular transmission and may have relevance to KCNH8-associated pathology.