【作者】 周源；

【导师】 谢利剑； 肖婷婷； 侯翠兰；

【作者基本信息】 上海交通大学 ， 儿科学（专业学位）， 2020， 硕士

【摘要】 目的对近3年内在上海市儿童医院心内科住院,并通过WES检测提示携带MYH7基因突变的心肌病患儿进行临床资料和检测结果的回顾,结合既往文献报道,以分析MYH7基因相关突变引起不同类型心肌病的临床表型及严重程度之间的关系。对于其中一例携带MYH7 c.788＿789del和c.2494C>T复合杂合突变的RCM患儿,本研究以明确突变对表型的影响并初步探讨可能存在的致病机制。方法通过查阅文献,对目前MYH7基因造成心肌病的突变位点报道情况进行总结,结合我院收治的病例,分析MYH7基因型与心肌病不同表型的关系。收集RCM家系(患儿及其父母)的外周血,行Sanger测序验证基因突变及突变的来源。用SIFT、Poly Phen2、Mutation Taster等在线软件对MYH7 c.788＿789del和c.2494C>T突变位点分别行突变预测分析。进一步建立蛋白质结构模型,对比突变蛋白与野生型蛋白结构。结果Sanger测序证实,在该家系中,诊断为RCM的患儿同时携带MYH7c.788＿789del(p.Ile263Argfs*29)和c.2494C>T(p.L832F)突变,这两个突变分别来源于母亲和父亲。在不同物种间比对发现,MYH7蛋白第263、832位氨基酸在进化过程中都存在高度保守性。致病性预测对这两个突变的预测结果均为有害。同源建模结果提示,这两个突变都造成了β-My HC结构的变化。结论MYH7基因突变类型、突变位点与关键结构域的位置关系以及突变的保守性是造成临床异质性和表型严重程度的关键因素。MYH7c.788＿789del和c.2494C>T突变很可能是导致患儿RCM的原因,复合杂合突变可能因“基因剂量效应”导致比单基因突变更严重的临床表型。对心肌病表型严重或有家族史的患者,应强调基因筛查的重要性。更多还原

【Abstract】 PurposeBy reviewing of clinical data and test results in children,in recent 3 years,who have been hospitalized in the department of cardiology of Shanghai children’s hospital and been diagnosed cardiomyopathy with MYH7 mutations which were detected by WES,and combining with previous literature reports,to preliminary discussion the mechanism of MYH7 mutation causing cardiomyopathy and understand the relationship between clinical phenotypes and severity of different types of cardiomyopathy caused by Different mutations in MYH7 gene.For the child who was diagnosed RCM with MYH7 c.788＿789del and c.2494C>T combined heterozygous mutation,this study was conducted to clarify the effect of mutations on phenotypes and to explore the possible pathogenesis.MethodsThrough literature review,the report of MYH7 gene mutation site causing cardiomyopathy was summarized.The relationship between MYH7 genotype and cardiomyopathy phenotype was discussed in combination with cardiomyopathy cases caused by MYH7 mutation in our hospital.Peripheral blood of the child who was diagnosed with RCM and his parents was collected,and Sanger sequencing was performed to verify gene mutations and their source.MYH7 c.788＿789del and c.2494C>T Mutation sites were predicted and analyzed by SIFT,Poly Phen2,Mutation Taster and other online software.Furthermore,protein structure models were established to compare the structure of the mutant protein with that of wild-type protein.ResultSanger sequencing confirmed that the children diagnosed with RCM in this family also carried mutations of MYH7 c.788＿789del(p.Ile263 Argfs *29)and c.2494C>T(p.L832F).The two mutations also came from the mother and the father.Comparison among different species showed that amino acids at positions 263 and 832 of MYH7 protein were highly conserved in the course of evolution.Prediction of pathogenicity was harmful to both mutations.Homologous modeling results suggest that both mutations contribute to change the structure of the β-myosin heavy chain.ConclusionType of MYH7 gene mutation and the location relationship between the mutation and key structural domains,as well as the conservation of mutation,is the key factors causing clinical heterogeneity and phenotypic severity.Mutations of MYH7 c.788＿789del and c.2494C>T are likely to cause RCM in the child.Compound heterozygous mutations may cause more severe clinical phenotypes than single gene mutations due to "gene dose effect".The importance of genetic screening should be emphasized especially in patients with severe cardiomyopathy phenotype or family history of cardiomyopathy.更多还原