【作者】 宫立国；

【导师】 孙开来；

【作者基本信息】 中国医科大学 ， 遗传学， 2003， 硕士

【摘要】 目的 先天性心脏病(congenital heart disease,CHD)是常见的出生缺陷，发病率为4％～8％。临床资料和流行病学研究表明，遗传因素在CHD的发病过程中发挥重要作用，遗传率为55％～65％。因此，从分子水平上研究控制心脏发育的相关基因，对于探讨心脏病变的机制及探索人类遗传性心脏病的治疗方案及手段具有重要意义。TBX5是近几年发现的、在心脏发育过程中起重要作用的一个转录因子。TBX5基因于1997年在Holt-Oram综合征(HOS)中首次被克隆。HOS，又称心手综合征，属于常染色体显性遗传病，病人表现为以房间隔缺损(ASD)为主的心脏异常和上肢不同部位、不同程度的畸形。国内外许多研究已证实TBX5基因突变将导致HOS的发生，但该基因突变或表达异常是否会导致人类单纯性CHD还未见相关报道。我们对TBX5基因在单纯性CHD中的突变和表达情况进行了研究，以期明确TBX5基因突变或表达水平的异常是否是单纯性CHD的致病原因之一。 方法 设计TBX5基因8个外显子引物，并于上游引物5’端加[GC]夹。应用聚合酶链反应一变性梯度凝胶电泳河CR－DGGE）的方法对61个人类单纯性CHD核心家系共216位成员进行了TBXS基因编码序列突变筛查；以非CHD患者心肌为正常对照，以p－achn为内对照，用RT－PCR方法检测TBXS基因在34例单纯性CHD患者（包括ASDJSD、民）右心耳中mRNA水平的表达情况。 结 果 所有216位成员 TBXS基因 8个外显子代R产物经 DGGE检测未发现突变；与非CHD患者（正常对照）相比，单纯性CHD患者＊＊D基因m＊＊A表达呈下降趋势（P＜0．OO豆），且防D、陀D。F．患者组间比较无明显差异冲＞0．05人 结 论 TBXS基因编码区的突变可能不是单纯性CHD的致病原因；TBXS基因转录水平异常可能是该基因参与CHD形成的一种潜在机制。更多还原

【Abstract】 Congenital heart disease(CHD) is a common newborn defect,the morbidity of which is from 4% to 8%. The clinical data and epidemio-logical study indicate that the genetic factors play an important role in the pathogenesis of CHD,and the heritability is from 55% to 65%. So identifying genes involved in the cardiac development from the molecular level is very important to find out the mechanism of CHD and make a better therapeutic program. TBX5 is a transcription factor that play a critical role during the cardiac development. TBX5 gene was identified and cloned from Holt - Oram syndrome ( HOS) in 1997. HOS belong to autosomal dominant and the patients were characterized by congenital heart defects and upper limb abnormalities. Studies have proved that TBX5 gene mutations would lead to HOS. But it is still unknown whether some mutations and abnormal expression of T-BX5 gene may cause human simple congenital heart disease. We in-vestigated the mutation and expression of TBX5 gene in human simple congenital heart disease so as to clear whether the mutations and the abnormality in transcription level of TBX5 gene is a kind of mechanism causing human simple congenital heart disease.Methodswe designed primers of 8 exons of TBX5 gene and added a [ GC ] clamp to the upper primer 5’ tip, then examined the mutations of coding sequence of TBX5 gene in 216 individuals from 61 CHD core pedigres by polymerase chain reaction - denaturing gradient gel electrophoresis (PCR - DGGE) ; Using (3 - actin as internal control , we detected the differential expression between 34 myocardium samples from simple congenital heart disease patients (including ASD, VSD and F4) and 3 normal controls by reverse transcription - polymerase chain reaction(RT - PCR) .ResultsNo mutations were detected in 8 exons of TBX5 gene in all samples by PCR - DGGE; The mRNA expression levels of TBX5 gene show descent tendency in samples of simple congenital heart disease compared with normal controls; There is no obvious difference between ASD, VSD and F4.ConclusionMutations in coding region of TBX5 gene may not cause humansimple congenital heart disease; The abnormality in transcription level of TBX5 gene may be a kind of mechanism causing human simple congenital heart disease.更多还原