Fig. 6: Schematic illustration of different pathophysiological mechanisms of KCNQ4 variants on DFNA2.

a Loss-of-function caused by KCNQ4 p.R331Q and its restoration following phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) activator (i.e., PIP5K) and channel openers. b Gain of function caused by KCNQ4 p.G319D and its restoration following interference of PIP2 activation by intracellular application of a polycation poly-L-lysine (PIP2 inhibitor) and channel inhibitor.