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Heart and Vessels

, Volume 29, Issue 4, pp 554–559 | Cite as

Congenital long QT syndrome with compound mutations in the KCNH2 gene

  • Sachiko Bando
  • Takeshi Soeki
  • Tomomi Matsuura
  • Toshiyuki Niki
  • Takayuki Ise
  • Koji Yamaguchi
  • Yoshio Taketani
  • Takashi Iwase
  • Hirotsugu Yamada
  • Tetsuzo Wakatsuki
  • Masashi Akaike
  • Takeshi Aiba
  • Wataru Shimizu
  • Masataka Sata
Case Report

Abstract

Congenital long QT syndrome is a genetic disorder encompassing a family of mutations that can lead to aberrant ventricular electrical activity. We report on two brothers with long QT syndrome caused by compound mutations in the KCNH2 gene inherited from parents who had no prolonged QT interval on electrocardiography. The proband had syncope, and his elder brother suffered from ventricular fibrillation. Genetic testing revealed that both brothers had multiple mutations in the KCNH2 gene, including a missense mutation of C1474T (exon 6) as well as a frameshift/nonsense mutation, resulting from the insertion of 25 nucleotides, which caused an altered amino acid sequence beginning at codon 302 and a premature termination codon (i.e., TAG) at codon 339 (exon 4). Family genetic screening found that their father had the same frameshift mutation, and their mother and sister had the same missense mutation, in the KCNH2 gene. However, these other family members were asymptomatic, with normal QT intervals on electrocardiography. These results suggest that compound mutations in the KCNH2 gene inherited independently from the parents made the phenotypes of their sons more severe.

Keywords

KCNH2 gene Long QT syndrome Compound mutation Missense mutation Frameshift mutation 

Notes

Acknowledgments

The authors thank Mr Naotaka Ohta of the Laboratory of Molecular Genetics, National Cerebral and Cardiovascular Center, for his excellent technical assistance.

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Copyright information

© Springer Japan 2013

Authors and Affiliations

  • Sachiko Bando
    • 1
  • Takeshi Soeki
    • 1
  • Tomomi Matsuura
    • 1
  • Toshiyuki Niki
    • 1
  • Takayuki Ise
    • 1
  • Koji Yamaguchi
    • 1
  • Yoshio Taketani
    • 1
  • Takashi Iwase
    • 1
  • Hirotsugu Yamada
    • 1
  • Tetsuzo Wakatsuki
    • 1
  • Masashi Akaike
    • 2
  • Takeshi Aiba
    • 3
  • Wataru Shimizu
    • 3
    • 4
  • Masataka Sata
    • 1
  1. 1.Department of Cardiovascular Medicine, Institute of Health BiosciencesThe University of Tokushima Graduate SchoolTokushimaJapan
  2. 2.Department of Medical Education, Institute of Health BiosciencesUniversity of Tokushima Graduate SchoolTokushimaJapan
  3. 3.Division of Arrhythmia and Electrophysiology, Department of Cardiovascular MedicineNational Cerebral and Cardiovascular CenterSuitaJapan
  4. 4.Department of Cardiovascular MedicineNippon Medical SchoolTokyoJapan

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