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遗传性长QT综合征(LQTS)是一种常染色体遗传性心脏病。特征性表现为心电图上QTc延长,及尖端扭转型室性心动过速(TdP)导致的晕厥和猝死。近年来随着分子遗传学的发展已明确遗传性LQTS是由于编码离子通道的基因或细胞骨架蛋白基因突变造成的,目前已发现1￣8种类型,致病基因分别为KCNQ1、KCNH2、SCN5A、ANK2、KCNE1,KCNE2、KCNJ2和Cav2.1。本研究目的是观察中国遗传性II型LQTS(LQT2)患者的临床特点及KCNH2突变。应用聚合酶链反应和测序分析,对来自中国19个省市自治区的77个遗传性LQTS家系筛查了LQT2致病基因KCNH2,观察临床表现和心电图改变。77例LQTS家系先证者中,心电图表现为LQT2者42例(54.5%),平均年龄(26.7±12.7)岁,QTc(580±70)ms,发病年龄(17.3±11.5)岁。晕厥触发因素包括运动、情绪激动和铃声刺激等。目前已经发现了9个KCNH2突变,其中4个为首先发现;另外还发现5个KCNH2的核苷酸多态性。证明LQT2为中国最常见的LQTS;中国LQT2患者心电图表现与临床特点与欧美LQT2患者有所不同。
Hereditary long QT syndrome (LQTS) is an autosomal dominant heart disease. Characteristically manifested as prolonged QTc on ECG, and torsades de pointes (TdP) induced syncope and sudden death. In recent years, with the development of molecular genetics has been identified hereditary LQTS is due to genes encoding ion channels or cytoskeleton protein gene mutation caused, has been found in 1 to 8 types of pathogenic genes were KCNQ1, KCNH2, SCN5A, ANK2, KCNE1, KCNE2, KCNJ2 and Cav2.1. The purpose of this study was to observe the clinical features and KCNH2 mutations in patients with Chinese hereditary type II LQTS (LQT2). Using polymerase chain reaction and sequencing analysis, 77 hereditary LQTS pedigrees from 19 provinces in China were screened for KCNH2, a gene of LQT2. The clinical manifestations and ECG changes were observed. Among 77 LQTS family members, 42 cases (54.5%) had LQT2 electrocardiogram, mean age (26.7 ± 12.7) years, QTc (580 ± 70) ms and age of onset (17.3 ± 11.5) years. Syncope trigger factors include exercise, emotional excitement and ring tones and so on. So far, nine KCNH2 mutations have been found, of which four were found first. Five KCNH2 nucleotide polymorphisms were also found. It is proved that LQT2 is the most common LQTS in China. The ECG performance and clinical features of LQT2 patients in China are different from those of LQT2 patients in Europe and America.