The G213D variant in Nav1.5 alters sodium current and causes an arrhythmogenic phenotype resulting in a multifocal ectopic Purkinje-related premature contraction phenotype in human-induced pluripotent stem cell-derived cardiomyocytes

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  • Kirstine Calloe, 1Copenhagen University Hospital, Copenhagen, Denmark. 2Aarhus University Hospital, Aarhus, Denmark. 3University of Copenhagen, Copenhagen, Denmark. 4Odense University Hospital, Odense, Denmark.
  • ,
  • Michelle Geryk, 1Copenhagen University Hospital, Copenhagen, Denmark. 2Aarhus University Hospital, Aarhus, Denmark. 3University of Copenhagen, Copenhagen, Denmark. 4Odense University Hospital, Odense, Denmark.
  • ,
  • Kristine Freude, 1Copenhagen University Hospital, Copenhagen, Denmark. 2Aarhus University Hospital, Aarhus, Denmark. 3University of Copenhagen, Copenhagen, Denmark. 4Odense University Hospital, Odense, Denmark.
  • ,
  • Jacqueline A Treat, Masonic Medical Research Institute
  • ,
  • Victoria A Vold, 1Copenhagen University Hospital, Copenhagen, Denmark. 2Aarhus University Hospital, Aarhus, Denmark. 3University of Copenhagen, Copenhagen, Denmark. 4Odense University Hospital, Odense, Denmark.
  • ,
  • Henriette Reventlow S Frederiksen, 1Copenhagen University Hospital, Copenhagen, Denmark. 2Aarhus University Hospital, Aarhus, Denmark. 3University of Copenhagen, Copenhagen, Denmark. 4Odense University Hospital, Odense, Denmark.
  • ,
  • Anders Krogh Broendberg
  • ,
  • Tanja Charlotte Frederiksen
  • Henrik K Jensen
  • Jonathan M Cordeiro, Masonic Medical Research Institute

AIMS: Variants in SCN5A encoding Nav1.5 are associated with cardiac arrhythmias. We aimed to determine the mechanism by which c.638G>A in SCNA5 resulting in p.Gly213Asp (G213D) in Nav1.5 altered Na+ channel function and how flecainide corrected the defect in a family with multifocal ectopic Purkinje-related premature contractions (MEPPC)-like syndrome.

METHODS AND RESULTS: Five patients carrying the G213D variant were treated with flecainide. Gating pore currents were evaluated in Xenopus laevis oocytes. The 638G>A SCN5A variant was introduced to human-induced pluripotent stem cell (hiPSC) by CRISPR-Cas9 gene editing and subsequently differentiated to cardiomyocytes (hiPSC-CM). Action potentials and sodium currents were measured in the absence and presence of flecainide. Ca2+ transients were measured by confocal microscopy. The five patients exhibited premature atrial and ventricular contractions which were suppressed by flecainide treatment. G213D induced gating pore current at potentials negative to -50 mV. Voltage-clamp analysis in hiPSC-CM revealed the activation threshold of INa was shifted in the hyperpolarizing direction resulting in a larger INa window current. The G213D hiPSC-CMs had faster beating rates compared with wild-type and frequently showed Ca2+ waves and alternans. Flecainide applied to G213D hiPSC-CMs decreased window current by shifting the steady-state inactivation curve and slowed the beating rate.

CONCLUSION: The G213D variant in Nav1.5 induced gating pore currents and increased window current. The changes in INa resulted in a faster beating rate and Ca2+ transient dysfunction. Flecainide decreased window current and inhibited INa, which is likely responsible for the therapeutic effectiveness of flecainide in MEPPC patients carrying the G213D variant.

OriginalsprogEngelsk
TidsskriftEuropace
ISSN1099-5129
DOI
StatusE-pub ahead of print - 21 jun. 2022

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© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

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