LQTS (long QT syndrome) is caused by mutations in cardiac ion channel genes; however, the prevalence of LQTS in the general population is not well known. In the present study, we prospectively estimated the prevalence of LQTS and analysed the associated mutation carriers in Japanese children. ECGs were recorded from 7961 Japanese school children (4044 males; mean age, 9.9±3.0 years). ECGs were examined again for children who had prolonged QTc (corrected QT) intervals in the initial ECGs, and their QT intervals were measured manually. An LQTS score was determined according to Schwartz's criteria, and ion channel genes were analysed. In vitro characterization of the identified mutants was performed by heterologous expression experiments. Three subjects were assigned to a high probability of LQTS (3.5≤ LQTS score), and eight subjects to an intermediate probability (1.0< LQTS score ≤3.0). Genetic analysis of these II subjects identified three KCNH2 mutations (M124T, 547–553 del GGCGGCG and 2311–2332 del/ins TC). In contrast, no mutations were identified in the 15 subjects with a low probability of LQTS. Electrophysiological studies showed that both the M124T and the 547–553 del GGCGGCG KCNH2 did not suppress the wild-type KCNH2 channel in a dominant-negative manner. These results demonstrate that, in a random sample of healthy Japanese children, the prevalence of a high probability of LQTS is 0.038% (three in 7961), and that LQTS mutation carriers can be identified in at least 0.038% (one in 2653). Furthermore, large-scale genetic studies will be needed to clarify the real prevalence of LQTS by gene-carrier status, as it may have been underestimated in the present study.
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September 21 2009
Long QT syndrome and associated gene mutation carriers in Japanese children: results from ECG screening examinations
Kenshi Hayashi;
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
Correspondence: Dr Kenshi Hayashi (email [email protected]).
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Noboru Fujino;
Noboru Fujino
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Katsuharu Uchiyama;
Katsuharu Uchiyama
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Hidekazu Ino;
Hidekazu Ino
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Kenji Sakata;
Kenji Sakata
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Tetsuo Konno;
Tetsuo Konno
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Eiichi Masuta;
Eiichi Masuta
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Akira Funada;
Akira Funada
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Yuichiro Sakamoto;
Yuichiro Sakamoto
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Toshinari Tsubokawa;
Toshinari Tsubokawa
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Keisuke Nakashima;
Keisuke Nakashima
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Li Liu;
Li Liu
† Department of Biophysical Genetics, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Haruhiro Higashida;
Haruhiro Higashida
† Department of Biophysical Genetics, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Yoshitake Hiramaru;
Yoshitake Hiramaru
‡ Cardiovascular Checkup Committee for School Pupils, Kanazawa Medical Association, Kanazawa, Japan
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Masami Shimizu;
Masami Shimizu
‡ Cardiovascular Checkup Committee for School Pupils, Kanazawa Medical Association, Kanazawa, Japan
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Masakazu Yamagishi
Masakazu Yamagishi
* Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, 13-1, Takara-machi, Kanazawa, Ishikawa 920-8640, Japan
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Publisher: Portland Press Ltd
Received:
October 15 2008
Revision Received:
March 23 2009
Accepted:
April 16 2009
Accepted Manuscript online:
April 16 2009
Online ISSN: 1470-8736
Print ISSN: 0143-5221
© The Authors Journal compilation © 2009 Biochemical Society
2009
Clin Sci (Lond) (2009) 117 (12): 415–424.
Article history
Received:
October 15 2008
Revision Received:
March 23 2009
Accepted:
April 16 2009
Accepted Manuscript online:
April 16 2009
Citation
Kenshi Hayashi, Noboru Fujino, Katsuharu Uchiyama, Hidekazu Ino, Kenji Sakata, Tetsuo Konno, Eiichi Masuta, Akira Funada, Yuichiro Sakamoto, Toshinari Tsubokawa, Keisuke Nakashima, Li Liu, Haruhiro Higashida, Yoshitake Hiramaru, Masami Shimizu, Masakazu Yamagishi; Long QT syndrome and associated gene mutation carriers in Japanese children: results from ECG screening examinations. Clin Sci (Lond) 1 July 2009; 117 (12): 415–424. doi: https://doi.org/10.1042/CS20080528
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