International Journal of Cardiology Gain-of-function mutation in SCN5A causes ventricular arrhythmias and early onset atrial fibrillation  Krystien V. Lieve, Arie O. Verkerk, Svitlana Podliesna, Christian van der Werf, Michael W. Tanck, Nynke Hofman, Paul F. van Bergen, Leander Beekman, Connie R. Bezzina, Arthur A.M. Wilde, Elisabeth M. Lodder  International Journal of Cardiology  Volume 236, Pages 187-193 (June 2017) DOI: 10.1016/j.ijcard.2017.01.113 Copyright © 2017 The Authors Terms and Conditions

Fig. 1 Pedigree of the family. Squares/circles indicate male/female respectively. Open symbols indicate unaffected persons. Symbols with a slash indicate deceased persons. Grey color indicates undetermined phenotype. The proband (III.4) is indicated by the arrow. SCN5A-p.M1851V mutation carriers are indicated by a plus sign, non-carriers with a minus sign and persons in which carriership is unknown with a question mark. Solid left upper quarter: early onset atrial fibrillation. Solid right upper quarter: exercise-induced ventricular arrhythmia. Solid left lower quarter: decreased left ventricular function. Solid right lower quarter: non-exercise induced ventricular arrhythmia. The numbers below the persons (i.e. II.2) represent the identification of the family members used in the text. International Journal of Cardiology 2017 236, 187-193DOI: (10.1016/j.ijcard.2017.01.113) Copyright © 2017 The Authors Terms and Conditions

Fig. 2 ECGs at rest (A) and during exercise (B and C) of subject III.1. A: sinus rhythm at rest. B: appearance of first premature ventricular contraction during exercise. C: non-sustained ventricular tachycardia during exercise. International Journal of Cardiology 2017 236, 187-193DOI: (10.1016/j.ijcard.2017.01.113) Copyright © 2017 The Authors Terms and Conditions

Fig. 3 Current density and gating properties of WT and M1851V channels. A, top: Typical examples of peak sodium current (INa) in response to 50-ms depolarizing voltage steps from −120mV. For protocol, see inset of panels B; cycle length was 5-s. A, bottom: Average fast and slow time constants of INa inactivation. Note logarithmic ordinate scale. τfast is significantly higher indicating a slowed current inactivation. B: Average current-voltage (I-V) relationships. C: Average steady-state (in)activation curves. Inset: voltage clamp for inactivation. The solid lines are the Boltzmann fit to the average data. Voltage-dependency of inactivation was significantly shifted towards more positive potentials in M1851V channels (−81.4±1.7mV (WT) vs −71.9±1.5mV (M1851V)), without changes in k. D: Average recovery from INa inactivation on a logarithmic time scale assessed with interpulse interval of 1–1000ms. Solid lines are double-exponential fits to the average data. Both average τfast (65±6ms (WT) vs 37±6ms (M1851V)) and τslow (1073±324ms (WT) vs 253±53ms (M1851V)) are significantly lower in M1851V channels indicating faster recovery from inactivation. E, top left: typical TTX-sensitive currents activated during a 300-ms depolarizing voltage steps from −120mV to −20mV. E, top right: average density of the TTX-sensitive sustained current measured during the last 50-ms of the depolarizing voltage step. Current density was not affected in the M1851V channels. E, bottom: Average INa window measured during a 200ms depolarizing ramp from −100 to −20mV from a −120mV holding potential (inset). The window current is significantly larger in M1851V channels. Asterisks denote p<0.05. F, top left: Upstrokes in HEK cells with WT or M1851V channels. Typical upstrokes measured upon switching from −85mV in voltage (VC) to current clamp for 20ms. The dashed line indicated the depolarization due the applied stimulus current alone. The arrow indicated the threshold for the upstroke and was measured at a 4-mV difference between the linear stimulus current and INa-drive voltage change. F, bottom left: first derivatives of the upstrokes depicted in panel F top left. F, top right: Average upstroke velocities. F, bottom right: average threshold voltages. Asterisks denote p<0.05. International Journal of Cardiology 2017 236, 187-193DOI: (10.1016/j.ijcard.2017.01.113) Copyright © 2017 The Authors Terms and Conditions