Swimming, a gene-specific arrhythmogenic trigger for inherited long QT syndrome

Mayo Clin Proc. 1999 Nov;74(11):1088-94. doi: 10.4065/74.11.1088.


Objective: To determine the genetic basis for long QT syndrome (LQTS) in a cohort of patients with a personal history or an extended family history of a swimming-triggered cardiac event.

Patients and methods: After review of the Mayo Clinic unit medical record system, blood samples or archived autopsy tissue samples were obtained from a retrospective cohort of 35 cases diagnosed as having autosomal dominant LQTS. Exon-specific amplification by polymerase chain reaction and direct sequence analyses were performed on the entire KVLQT1 gene.

Results: Six cases had a personal history or an extended family history of a near drowning or drowning. In all 6 cases, LQTS-causing mutations in KVLQT1 gene were identified: 3 deletion mutations, 2 donor splice site mutations, and 1 missense mutation. One of the mutations, a novel donor splicing defect, was determined by postmortem molecular analysis of a paraffin-embedded tissue block from a 12-year-old girl who died in 1976. Distinct KVLQT1 mutations were demonstrated in 3 of the remaining 29 cases. The overall frequency of KVLQT1 defects in LQTS was 100% (6/6) in those with and 10% (3/29) in those without a personal history or an extended family history of drowning or near drowning (P<.001).

Conclusion: Swimming appears to be a gene-specific (KVLQT1) arrhythmogenic trigger for LQTS. This study provides proof of principle that an unexplained drowning or near drowning may have a genetic basis.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Drowning / genetics*
  • Female
  • Humans
  • Long QT Syndrome / genetics*
  • Male
  • Mutation*
  • Polymerase Chain Reaction
  • Retrospective Studies
  • Swimming*