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Drug-induced long-QT syndrome associated with a subclinical SCN5A mutation

Naomasa Makita1, Minoru Horie, Takeshi Nakamura

  • 1Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan. makitan@med.hokudai.ac.jp

Circulation
|September 5, 2002
PubMed
Abstract

Insights

Subclinical mutations in the SCN5A gene can increase the risk of drug-induced long-QT syndrome (LQTS) and dangerous arrhythmias. This study identified a novel mutation predisposing an individual to acquired LQTS.

Area of Science:

  • Cardiovascular Genetics
  • Molecular Cardiology
  • Pharmacogenomics

Background:

  • Congenital long-QT syndromes (LQTS) are linked to mutations in cardiac ion channel genes.
  • Subclinical genetic variants may increase susceptibility to acquired LQTS and arrhythmias.
  • Investigating novel mutations in LQTS-related genes is crucial for understanding drug-induced arrhythmias.

Observation:

  • A novel missense mutation, L1825P, was identified in the SCN5A gene of a patient experiencing drug-induced torsade de pointes.
  • The L1825P mutation in the cardiac sodium channel (SCN5A) exhibited dual gain-of-function and loss-of-function properties.
  • Functional analysis revealed altered Na+ current decay, a noninactivating component, and diminished peak current density.

Findings:

  • The identified L1825P mutation in SCN5A presents a unique phenotype with characteristics of both LQT3 and Brugada syndrome.
  • This mutation significantly alters cardiac sodium channel function, affecting activation and inactivation properties.
  • The study confirms a link between subclinical SCN5A mutations and acquired LQTS.

Implications:

  • Subclinical SCN5A mutations represent a significant risk factor for developing drug-induced cardiac arrhythmias.
  • Genetic screening for SCN5A variants may be beneficial in patients at risk for acquired LQTS.
  • Understanding these genetic predispositions can guide personalized medicine approaches in cardiovascular pharmacotherapy.

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