Gain-of-function mutation S422L in the KCNJ8-encoded cardiac K(ATP) channel Kir6.1 as a pathogenic substrate for J-wave syndromes.

J wave syndromes have emerged conceptually to encompass the pleiotropic expression of J point abnormalities including Brugada syndrome BrS and early repolarization syndrome ERS KCNJ8 which encodes the cardiac K ATP Kir6 1 channel recently has been implicated in ERS following identification of the functionally uncharacterized missense mutation S422L