QT延長症候群（LQTS）はイオンチャネルあるいはイオンチャネルに影響を与えるタンパクをコードする遺伝子の遺伝子変異による心筋細胞の再分極異常により，心電図上，QT時間の延長，倒錯型心室頻拍（torsade de pointes）を示し，失神，けいれん，心臓突然死，救命された心停止を主症状とする疾患である．責任遺伝子として17種が報告されているが，見直しが始まっている．主要なタイプはLQT1，LQT2，LQT3の3型である．遺伝子変異が見つかるのは約2,000人に1人，学校心臓検診（心臓検診）でLQTSの診断基準を満たすのは中学1年時で約1,000人に1人である．治療は遺伝型と表現型（症状）との関連に基づいて行われる．生活指導の徹底，薬物療法の改善等によりLQTS, 特に心臓検診で診断されるLQTSの予後は著明に改善されつつある．
Congenital long QT syndrome (LQTS), a genetic disorder, is characterized by delayed repolarization and a long QT interval on 12-lead electrocardiography (ECG). The hallmark of LQTS is syncope, convulsion, sudden cardiac death, and aborted cardiac arrest caused by torsade de pointes. Variations in genes encoding for cardiac ion channels, accessory ion channel subunits, or proteins modulating the function of the ion channel have been identified in 17 genes as disease-causing mutations. However, an international, evidence-based reappraisal of genes reported that LQT1, LQT2, and LQT3 are the major three types. The genetically determined prevalence of LQTS is approximately 1 : 2000. In the general population, the probability of diagnosing LQTS through ECG is 1 : 1000 in seventh graders (aged 12 years). Treatment was implemented based on the genotype–phenotype relationship. The prognosis of patients with LQTS, particularly those who are diagnosed by a school-based ECG screening program, has been improving through the control of lifestyles and well adherence to pharmacotherapy.
Key words: long QT syndrome; screening program; electrocardiogram
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This page was created on 2023-12-11T14:52:15.022+09:00
This page was last modified on 2023-12-25T11:01:18.000+09:00
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