Postmortem long QT syndrome genetic testing for sudden unexplained death in the young

J Am Coll Cardiol. 2007 Jan 16;49(2):240-6. doi: 10.1016/j.jacc.2006.10.010. Epub 2006 Dec 29.


Objectives: This study sought to determine the spectrum and prevalence of long QT syndrome (LQTS)-associated mutations in a large cohort of autopsy-negative sudden unexplained death (SUD).

Background: Potentially heritable arrhythmia syndromes may explain a significant proportion of SUD in the young. Here, comprehensive postmortem LQTS genetic testing was performed in a cohort of SUD cases.

Methods: From September 1998 to March 2004, 49 cases of SUD (30 male patients, average age at death 14.2 +/- 10.9 years) were referred by medical examiners/coroners to Mayo Clinic's Sudden Death Genomics Laboratory. Using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct DNA sequencing, open reading frame/splice site mutational analysis was conducted for all 8 genes implicated in the pathogenesis of either LQTS (LQT1 to LQT6) or multisystem disorders involving either QT or QU prolongation.

Results: Ten LQTS-associated mutations (4 novel) were discovered in 10 SUD cases (20%, 8 female patients, average age at death 18.0 +/- 11.8 years). The LQTS susceptibility mutations LQT1 (5), LQT2 (3), and LQT3 (2) were far more common among women (8 of 18, 44%) than men (2 of 30, 6.7%, p < 0.008). The activities at the time of SUD included sleep (5), exertion (2), auditory arousal (1), and undetermined (2). Sudden death was the sentinel event in two-thirds of the cases.

Conclusions: In this cardiac channel-focused molecular autopsy investigation of SUD, over one-third of decedents harbored a putative cardiac channel mutation: 7 previously reported to host mutations in the RyR2-encoded calcium release channel and now 10 with LQTS susceptibility mutations. Accordingly, postmortem cardiac channel genetic testing should be pursued in the evaluation of autopsy-negative SUD.

MeSH terms

  • Adolescent
  • Adult
  • Age Distribution
  • Autopsy
  • Causality
  • Cause of Death
  • Child
  • Cohort Studies
  • Confidence Intervals
  • DNA Mutational Analysis
  • Death, Sudden / epidemiology
  • Death, Sudden / etiology
  • Death, Sudden / pathology
  • Death, Sudden, Cardiac / epidemiology*
  • Death, Sudden, Cardiac / pathology
  • Diagnosis
  • Female
  • Genetic Predisposition to Disease
  • Humans
  • KCNQ1 Potassium Channel / genetics*
  • Long QT Syndrome / diagnosis
  • Long QT Syndrome / genetics*
  • Long QT Syndrome / mortality*
  • Male
  • Mutation
  • Polymorphism, Genetic
  • Retrospective Studies
  • Ryanodine Receptor Calcium Release Channel / genetics*
  • Sensitivity and Specificity
  • Sex Distribution


  • KCNQ1 Potassium Channel
  • KCNQ1 protein, human
  • Ryanodine Receptor Calcium Release Channel