先天性室间隔缺损并室性心律失常致病基因筛查及其分子遗传、电生理机制研究

Congenital ventricular septal defect (VSD) significantly increased the risk of ventricular arrhythmias (VA) and sudden cardiac death (SCD).VSD and some inherited arrhythmia disorders are related to abnormal expression of cardiac developmental genes and ion channel gene. Recently we performed genetic screen in patients with congenital isolated VSD complicated with VA, and we found one proband had a new variation of KCNQ1 gene. One electrophysiological study studies showed that the gene phenotypes of cardiomyopathy was related with the substract of VA generating. Considered with the above facts, we hypothesis that there may be some unknown gene mutations or genes exist in patient with congenital VSD and VA , which contributed to the combined presence of VSD and VA, and the type of genetic variation may be related to their electrophysiological characteristics. There is no report about the molecular genetics of patients with VSD and VA. In this study we will perform further genetic screening of such patients to find unknown mutation or gene, if the new muntation or gene was find, the mutation or gene will be performed with molecular genetics functional analysis, and the electrophysiology examine will performed at last. Therefore, we can further elucidate the pathogenesis of VSD and the mechanisms contributed to the present of VA in these patients. And this study is helpful to assessment risk of patient with VSD. Further more, it also can provide some ideas for the gene therapy of future.

先天性室间隔缺损（VSD）明显增加室性心律失常（VA）及心源性猝死（SCD）的风险。VSD及一些遗传性心律失常疾病与心脏发育基因及离子通道基因表达异常有关。我们对单纯先天性VSD并VA患者进行基因筛查，发现1例先证者的KCNQ1基因存在新变异。有电生理检查研究表明基因表型与心肌病VA产生所依赖的基质相关。由此我们推论：先天性VSD并VA患者可能存在新的突变或新基因，导致VSD与VA合并存在，且其基因变异类型可能与电生理特点相关。目前尚未见VSD并VA患者分子遗传学研究报道。本研究拟对此类患者行进一步基因筛查，并对新发现突变或基因行分子遗传学功能分析及电生理机制研究，以进一步阐明VSD的致病病因及其产生VA的相关机制，为VSD患者的风险评估提供参考，并可为今后的基因治疗提供思路。

1、我们对先证室间隔缺损（VSD）并室性心律失常（VA）患者共13人进行基因筛查，原始实验中发现1例单纯VSD合并VT的男性存在KCNQ1基因新变异，2号外显子上第430位碱基A变为T,氨基酸由苏氨酸变为丝氨酸（T144S）。但在准备进行功能分析时，我们对该患者KCNQ1基因序列进行多次复核，发现其突变结果无法重复，确认此人群无常规基因突变，我们决定转换研究方向：对VSD人群进行结构基因多态性的筛查。.2、目的：探讨Ellis-van Creveld（EVC）基因与VSD相关性。方法：1、检测中国汉族65名VSD患者和对照组210名正常人单核苷酸多态性（SNPs），在鉴定的SNP中，只有c.1727G> A SNP位点与VSD的发展呈正相关（P <0.007）。还鉴定了一种已知的突变c.343C> G，其导致EVC蛋白质的氨基酸115处亮氨酸至缬氨酸的置换（p.L115V）。功能预测结果显示c.343C> G可能是致病性突变。2、突变功能分析：在NIH3T3小鼠胚胎成纤维细胞中，EVC c.343C> G突变显着降低细胞增殖并增加细胞凋亡。我们进一步的研究表明，在NIH3T3细胞中，EVC c.343C> G突变的过表达降低了EVC之间的结合及其平滑化，并下调了Hedgehog信号通路的活性。结论：中国汉族人群的EVC基因c.1727G> A SNP增加了VSD易感性。由EVC c.343C> G突变诱导VSD发生的分子机制可能是由于通过下调Hh途径活性而减少心肌细胞的抗凋亡和增殖能力。本研究的结果可为VSD患者的诊断和治疗提供新的靶点。