Molecular mechanism for an inherited cardiac arrhythmia

Nature. 1995 Aug 24;376(6542):683-5. doi: 10.1038/376683a0.


In the congenital long-QT syndrome, prolongation of the cardiac action potential occurs by an unknown mechanism and predisposes individuals to syncope and sudden death as a result of ventricular arrhythmias. Genetic heterogeneity has been demonstrated for autosomal dominant long-QT syndrome by the identification of multiple distinct loci, and associated mutations in two candidate genes have recently been reported. One form of hereditary long QT (LQT3) has been linked to a mutation in the gene encoding the human heart voltage-gated sodium-channel alpha-subunit (SCN5A on chromosome 3p21). Here we characterize this mutation using heterologous expression of recombinant human heart sodium channels. Mutant channels show a sustained inward current during membrane depolarization. Single-channel recordings indicate that mutant channels fluctuate between normal and non-inactivating gating modes. Persistent inward sodium current explains prolongation of cardiac action potentials, and provides a molecular mechanism for this form of congenital long-QT syndrome.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Action Potentials
  • Animals
  • Cells, Cultured
  • Computer Simulation
  • Humans
  • Ion Channel Gating / genetics
  • Long QT Syndrome / genetics*
  • Long QT Syndrome / metabolism
  • Mutation*
  • Myocardium / metabolism*
  • Oocytes
  • Patch-Clamp Techniques
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sodium Channels / genetics*
  • Sodium Channels / metabolism
  • Xenopus laevis


  • Recombinant Proteins
  • Sodium Channels