KCNQ1 and gingival overgrowth: The physiological importance of this feature of heteromeric Q1E2 channels can be inferred from the pathophysiological effects of the studied KCNQ1 variants: the heterozygous gain-of-function variants R116L, P369L and V185M commonly lead to high-constitutive Q1E2 conductance that underlies maternally inherited gingival overgrowth, with or without postnatal growth retardation.