Impact of six selected KCNN2 variants on SK2 channel functional expression. (A) Representative traces of whole cell current recorded from CHO-K1 cells transiently transfected with human wild-type (WT) or mutant hKCNN2 plasmid during a voltage ramp protocol using the patch-clamp technique. Each current trace is the steady-state current obtained after calcium dialysis following the establishment of the whole cell configuration. hKCNN2 p.Leu321del (n = 5), p.Ile359Met (n = 5), p.Gly362Ser (n = 5), p.Leu388Val (n = 8) and p.Leu432Pro (n = 9) mutants do not conduct functional SK2 currents whereas hKCNN2 p.Glu30Gln (n = 8) conducts a SK2 current similar to that expressed by hKCNN2 wild-type (n = 22). (B) Time course of current amplitudes at 55 mV recorded from the cells shown in A, voltage ramp protocols being applied every 5 s. (C) Box plots of the current density for wild-type and p.Glu30Gln (E30Q) showing the median (horizontal line), the 25–75% percentile range (box) and range within 1.5 IQR (whiskers). Numbers of experiment from different cells are shown in parentheses. Statistical analysis between groups was performed with the Kruskal-Wallis ANOVA on ranks (Mann-Whitney rank-sum test, P = 0.121).