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Mutation detection of cardiac ion channel genes in sudden death cases

猝死病例心脏离子通道基因突变检测

基本信息

批准号：
11470121
负责人：
SUZUKI Koichi
金额：
$ 8.32万
依托单位：
Osaka Medical College
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

In the sudden death of a young adult, which is unexplained by a morphorogical examination and is unexpected by past history, we contructed a working theory that ion channels expressed in cardiac conducting system may be involved in the sudden death because long QT syndrome (LQT) has been shown to be caused by mutations in various ion channel genes.HERG, KVLQT, and SCN5A of which mutations cause LQT, and Kir6.2, GIRK1, GIRK4, and MAXIK were analyzed for mutations in eight sudden death cases and 100 healthy controls. A C to T transition in an intron of GIRK4 was found to be the only candidate mutation for sudden death on the basis of the function of the GIRK4 associated channel (I_<KACh>). The transition was assumed to change the splice donor site, leading to premature introduction of stop codon in the following exon. The mRNA was expected to be 5 bp longer than usual one. RT-PCR of ectopically expressed mRNA in leucocytes recovered from a healthy individual homozygous for the mutation failed to show the longer mRNA but this result does not mean that the presumed splice variant is not produced in impulse' conducting system. Only a small fraction of the truncated GIRK4 must decrease the I_<KACh> channel by dominant negative effect, thus resulting in functional impairment of the I_<KACh> channel.In addition to the GIRK4 mutation, several polymorphic mutations were identified in the other channel genes but all of them were found to be neutral variants. In this study, mutation has not been searched for along the total length of the genes. Further screening for mutation of the genes will be required.

在形态学检查无法解释且过去病史无法预料的年轻人猝死中，我们构建了一个工作理论，即心脏传导系统中表达的离子通道可能与猝死有关，因为长QT综合征（LQT）已被证明是由多种离子通道基因突变引起的。HERG、KVLQT和SCN5A（其中突变导致LQT）和Kir6.2，对 8 名猝死病例和 100 名健康对照者的 GIRK1、GIRK4 和 MAXIK 进行了突变分析。根据 GIRK4 相关通道 (I_<KACh>) 的功能，发现 GIRK4 内含子中的 C 到 T 转变是猝死的唯一候选突变。假定该转变改变了剪接供体位点，导致在随后的外显子中过早引入终止密码子。预计 mRNA 比通常的 mRNA 长 5 bp。从突变纯合健康个体中回收的白细胞中异位表达的 mRNA 的 RT-PCR 未能显示更长的 mRNA，但该结果并不意味着脉冲传导系统中不会产生假定的剪接变体。只有一小部分截短的 GIRK4 必须通过显性负效应降低 I_<KACh> 通道，从而导致 I_<KACh> 通道功能受损。除了 GIRK4 突变外，在其他通道基因中还发现了几个多态性突变，但发现它们都是中性变异。在这项研究中，并未沿着基因的全长寻找突变。需要进一步筛选基因突变。