KCNK4 encodes a two-pore-domain potassium channel that conducts voltage-dependent outward rectifying currents and converts to voltage-independent leak conductance in response to mechanical stretch, pH changes, heat, and lipids. The channel forms homo- and heterodimers with other K2P family members (such as KCNK2/TREK-1) and is widely distributed across tissues including heart, brain, liver, and skeletal muscle, with particular importance at nodes of Ranvier in myelinated sensory nerves where it enables rapid action potential repolarization and mechanosensitive/thermosensitive signaling. De novo gain-of-function variants in KCNK4 cause facial dysmorphism, hypertrichosis, epilepsy, intellectual/developmental delay, and gingival overgrowth (FHEIG) syndrome 1. These mutations increase baseline K+ channel activity and impair sensitivity to mechanical stimulation and arachidonic acid, likely by altering lateral fenestration geometry that normally restricts potassium flow 1. The syndrome shows variable phenotypic expressivity; some carriers present only hypertrichosis and gingival overgrowth without neurological manifestations 2. A broader spectrum of epilepsy presentations, including Rolandic epilepsy, has been associated with KCNK4 variants, with phenotypic severity potentially linked to the subcellular location of mutations 3. Carbamazepine, oxcarbazepine, and valproate may be effective antiepileptic treatments 3. KCNK4 variants also emerge as candidates in bipolar disorder risk mapping 4.