中文摘要：

目的对遗传性长QT间期综合征（long QT syndrome,LQTS）家系进行遗传分析,观察该家系成员发病的临床症状和心电图特点,推测其相应的致病基因型。方法家系共有6个成员被纳入研究。采集家系成员外周血,提取其基因组DNA。分析先证者及家系成员的临床资料和心电图资料,用PCR和直接测序法对致LQTS的KCNQ1、KCNH2、SCN5A基因编码区全部序列进行基因突变筛查。结果家系成员中共有LQTS患者3例,其中猝死1例,晕厥发作1例,无明显症状1例;共采集到2例LQTS患者心电图2例,QT间期分别为0.6 s和0.54 s。经基因检测发现,在两例患者中均发现了1个LQTS易感的单核苷酸多态性（SNP）位点SCN5A H558R,其他基因均未发现异常。结论在此遗传性LTQS中发现了一个易感SNP位点,推测此两例遗传性LQTS患者均为3型。

英文摘要：

Objective To investigate the clinical symptoms,electrocardiogram（ ECG） features and pathogenic genotypes in a family members with inherited long QT syndrome（ LQTS）. Methods Six family members were enrolled in the study. Their peripheral blood samples were drawn and the genomic DNA was extracted. Their clinical data and ECG recordings were analyzed,and the sequences of KCNQ1,KCNH2 and SCN5A genes were determined by polymerase chain reaction（ PCR） and direct sequencing to screen genetic mutations. Results There were 3 patients with LQTS in the family. Among them,one suffered from sudden death,another had syncope and the other was asymptomatic. Two of the three patients had ECG records,and their QT intervals were 0. 6 s and 0. 54 s,respectively. Moreover,the susceptible single nucleotide polymorphism（ SNP） H558R in SCN5A gene was found in the two patients. Conclusion The existence of susceptible SNP in SCN5A gene in the patients with LQTS indicated that the LQTS in this family belonged to LQT3 type.