“良性”MYH7基因Val606Met突变导致恶性肥厚型心肌病

目的研究汉族人群家族性肥厚型心肌病的致病基因突变位点,分析基因型与临床表型的关系。方法采集1个家族性肥厚型心肌病(HCM)家系成员的血液样本,并收集临床表型资料;对该家系先证者的28个HCM相关致病基因利用高通量测序进行靶向重测序;利用Sanger测序在家系成员中检测发现的致病突变位点;分析致病突变携带者的临床表型特点。结果高通量测序和Sanger测序发现并证实先证者携带β肌球蛋白重链基因(MYH7)Val606Met杂合错义突变,该突变在307名正常对照未检出;其他27个HCM相关致病基因中,未检出致病突变。家系遗传筛查发现3例HCM患者均携带MYH7基因Val606Met错义突变,该突变与HCM共分离。该家系3例HCM患者伴有心悸、胸痛、黑矇、晕厥等症状,先证者已经出现严重的心力衰竭,接受心脏移植后上述症状消失,生活质量明显改善。该家系另有2名成员在调查前发生心源性猝死。结论虽然有报道MYH7基因Val606Met错义突变为良性突变,但在本研究家系中,易导致早发心衰和猝死。因突变引起的终末期心衰接受心脏移植可能为最佳的治疗手段。     

汉族家族性肥厚型心肌病人群MYH7基因Val606Met突变分析

目的研究中国汉族人群家族性肥厚型心肌病的致病基因突变位点,对基因型与临床表型之间的关系进行分析。方法对8个肥厚型心肌病家系的先证者进行β-肌球蛋白重链基因扫描,聚合酶链反应扩增其功能区的外显子片段,双脱氧末段终止法测序。对阳性结果患者进行家系调查,收集临床资料,分析其临床表型特点。结果在1个家系中发现Val606Met杂合突变,而正常对照组同一位置未见异常。结论β-肌球蛋白重链基因可能是我国家族性肥厚型心肌病的常见致病基因之一。Val606Met错义突变位于肌球蛋白重链的肌动蛋白结合位点,该部位系肌球蛋白的重要功能区,其临床表型的异质性,提示多因素参与了肥厚型心肌病的发生和发展。     

家族性肥厚型心肌病患者MYBPC3基因突变筛查

目的:研究中国汉族人群家族性肥厚型心肌病(FHCM)患者的致病基因突变位点,分析其基因型与表型关系。方法:对6个家系先证者行肌球连接蛋白-C基因(MYBPC3)筛查,聚合酶链反应扩增其MYBPC3基因13、15-16、26、及27号功能区外显子片断,双脱氧末端终止法测序。对阳性结果者家系中其他成员及健康对照组同一位置筛查,分析患者基因型及临床表型特点。结果:在2个家系中,同时发现MYBPC3基因Val896Met杂合突变,而健康对照组同一位置未见异常,2家系中共6人携带此突变,其中发病5例;该突变可能为我国汉人FHCM家系中首次发现。结论:MYBPC3是我国汉族FHCM患者的常见致病基因;MYBPC3基因Val896Met突变所致肥厚型心肌病外显率高、临床症状出现较晚、进展缓慢、出现明显年龄依赖性特点,为一种良性突变。     

用变性高效液相色谱检测和脱氧核糖核酸测序方法对三个肥厚型心肌病家系β肌球蛋白重链基因突变的分析结果

目的:研究家族性肥厚型心肌病(HCM)的主要致病基因β肌球蛋白重链(MYH7)基因突变情况.方法:用变性高效液相色谱(DHPLC)检测和脱氧核糖核酸(DNA)测序方法对三个肥厚型心肌病家系成员的MYH7基因8、14外显子及附近上下游序列进行检测分析;另选正常对照者50例.结果:三个家系其中一个家系发现MYH7基因14外显子中存在Thr441Met突变,外显子8也存在一个点突变.另外两个家系均存在外显子8的C到T的突变,但表型不一.其中一个家系还存在内含子13和19的多态位点.此外,三个家系MYH7基因第3外显子均发现同义突变.结论:MYH7基因在肥厚型心肌病家系中具有较高的突变率.运用变性高效液相色谱技术,能够快速有效的进行基因突变筛查.     

MYBPC3基因G12101A和MYH7基因G15391A突变与肥厚型心肌病临床表型

目的 研究中国人家族性肥厚型心肌病(HCM)的致病基因突变位点,分析基因型与临床表型的相互关系.方法 在2个中国汉族HCM家系中进行心脏肌钙蛋白T基因(TNNT2)、心脏肌球蛋白结合蛋白C基因(MYBPC3)和心脏β-肌球蛋白重链基因(MYH7)的突变筛查,聚合酶链式反应(PCR)扩增基因功能区外显子片段并对PCR产物进行测序分析.结果 在ZZJ家系接受调查的8名成员中有4名成员携带MYBPC3基因G12101A杂合突变,该突变位点位于MYBPC3基因的21号外显子并使668位的精氨酸(R)转换为组氨酸(H),携带该突变的家族成员发病年龄较晚且均无梗阻及晕厥史.在FHL家系接受调查的6名成员中有3名成员携带MYH7基因G15391A杂合突变,该突变位点位于MYH7基因的23号外显子并使930位的谷氨酸(E)转换为赖氨酸(K),该突变导致的临床表型呈现发病年龄早、梗阻率高以及外显率高的特点.两家系成员TNNT2基因未发现突变,且正常对照组相同位置未发现异常.结论 MYBPC3基凶和MYH7基因是我国家族性HCM的致病基因,MYBPC3基因G12101A突变所致HCM临床症状相对较轻,而MYH7基因G15391A突变所致HCM临床症状出现早、进展较快且预后较差,是一种恶性突变.     

肥厚型心肌病致病基因型与临床表现的关系及基因筛查在肥厚型心肌病筛查及疾病鉴别诊断中的作用

目的:分析肥厚型心肌病(HCM)致病基因型与临床表现的关系及基因筛查在HCM筛查及疾病鉴别诊断中的作用。方法:选择一个HCM家系共14人,多重靶向测序技术对先证者的26个已知最常见的HCM致病基因进行全外显子捕获测序,用Sanger测序对发现的突变进行验证并对其他家系成员及307名健康对照进行该突变位点的筛查,分析其基因型与临床表型的特点。结果:先证者及其子携带MYH7基因c.2146 GA(Gly716Arg)突变,该突变位于MYH7基因19号外显子,导致第716位氨基酸残基由Gly变为Arg,其他25个基因未发现突变。Sanger测序验证后对其他家系成员进行突变筛查,其他家庭成员及对照组未发现该突变,该突变与HCM在该家系中共分离。先证者携带的致病突变为从头突变,并遗传给其子。先证者临床表现为发病早(14岁)、劳力性呼吸困难、胸痛、心悸、心力衰竭,其子出生时即发现心肌肥厚。其父虽然室间隔肥厚(15 mm),但结合其年轻时曾为运动员的经历及遗传筛查的阴性结果,可基本排除其为HCM患者,考虑为生理性肥厚。结论:该家系HCM由MYH7基因从头突变p.Gly716Arg导致,该突变临床发病早,症状较重,预后较差,为恶性突变。基因筛查在HCM家系筛查及疾病鉴别诊断中有重要意义。     

TNNI3基因Arg186Gln突变与家族性肥厚型心肌病的相关性分析

目的:研究中国汉族人群家族性肥厚型心肌病(HCM)常见致病基因突变位点,并对基因型与临床表型关系进行分析。方法:利用靶向外显子捕获测序方法对9例家族性HCM家系先证者进行MYH7、MYBPC3、TNNT2及TNNI3基因全外显子扩增和高通量测序,使用Sanger测序法在家系内进行验证。对阳性结果患者进行家系调查研究,调查资料包括一般临床症状、心电图、超声心动图以及3.0T心脏磁共振。进行门诊或电话定期随访,随访时间为1年或至患者死亡。结果:在其中1个家系中发现TNNI3基因第8号外显子Arg186Gln突变,该突变使遗传密码发生G→A转变,从而使其所编码的186位氨基酸由精氨酸(Arg)变为谷氨酰胺(Gln)。该家系中除先证者外还存在2例HCM患者,先证者为体检时发现心电图异常前来就诊,无临床症状,其父时有胸闷,在研究调查过程中猝死,其祖母胸闷气促症状明显。健康对照组中未发现上述基因突变。结论:家族性HCM患者TNNI3基因突变位点为Arg186Gln,携带该突变基因型的HCM患者呈现的临床表型不同,具有明显的临床异质性。     

β-肌球蛋白重链基因Ala26Val突变中国人肥厚型心肌病热点突变

目的 研究中国人肥厚型心肌病致病基因，分析基因型与临床表型的关系。方法 在86例肥厚型心肌病患及120例正常对照中进行β-肌球蛋白重链（β-MHC）基因扫描，聚合酶链反应（PCR）扩增其功能区的外显子片段，双脱氧末段终止法测序，对阳性结果进行家系调查，收集临床资料，分析其临床表型。结果 在3个家系及1例散发患中发现β-MHC基因第3号外显子的Ala26Val错义突变，正常对照组同一位置未见异常，3个家系临床表型不同。结论 β-MHC基因Ala26Val突变是中国人肥厚型心肌病的热点突变，其临床表型的异质性，提示多因素参与了肥厚型心肌病的发生和发展。     

中国汉族家族性肥厚型心肌病中首次发现MYH7基因Ile736Thr突变

目的 研究中国汉族人家族性肥厚型心肌病的致病基因突变位点,分析基因型与临床表型的相互关系。方法 对3个患家族性肥厚型心肌病家系的先证者进行β肌球蛋白重链基因(MYH7)扫描,聚合酶链式反应扩增其功能区外显子片断,双脱氧末端终止法测序。对阳性结果者进行家系中其他成员的筛查,全部进行β肌球蛋白重链基因目的片段的筛查,并分析家系中患者的临床表型特点。结果 在1个家系中发现Ile736Thr杂合突变,而正常对照组同一位置未见异常,Ile736Thr为我国患者中首次发现。结论 β肌球蛋白重链基因可能为我国家族性肥厚型心肌病的主要致病基因之一。Ile736Thr所致肥厚型心肌病其临床症状出现较晚,但进展快,易发生心力衰竭,预后较差。     

中国北方汉族家族性肥厚型心肌病人群MYH7基因Arg694Leu突变分析

目的研究中国北方汉族人群家族性肥厚型心肌病的致病基因突变位点,分析基因型与表型的关系。方法对4个肥厚型心肌病家系的先证者以及90名健康人进行β－肌球蛋白重链基因扫描,聚合酶链反应扩增其功能区的外显子片段,双脱氧末段终止法测序。对阳性结果患者进行家系调查,收集临床资料,分析其临床表型。结果在1个家系中发现Arg694Leu杂合突变,而正常对照组同一位置未见异常,此为我国患者中首次发现Arg694Leu突变。结论β－肌球蛋白重链可能是我国家族性肥厚型心肌病的常见致病基因之一和主要致病基因之一。Arg694Leu所致肥厚型心肌病外显率较高,临床症状出现较晚,进展慢,预后较好,猝死及心腔扩大少见,是一相对良性突变。     

Characteristics of the beta myosin heavy chain gene Ala26Val mutation in a Chinese family with hypertrophic cardiomyopathy

BACKGROUND: Genotype-phenotype studies have suggested that some mutations of genes encoding various components of the cardiac sarcomere cause hypertrophic cardiomyopathy (HCM) and are associated with the prognosis of patients with HCM. The aims of this study were to investigate the gene mutations of exons in the cardiac beta myosin heavy chain (MYH7) gene, the troponin T (TNNT2) gene, and the brain natriuretic peptide (BNP) gene, as well as to assess the effect of these mutations on the clinical features of Chinese patients with HCM. METHODS: Five unrelated Chinese families with HCM were studied. Exons 3 and 18 in the MYH7 gene, exon 9 in the TNNT2 gene, and all three exons in the BNP gene were screened with the polymerase chain reaction (PCR) for genomic DNA amplification. Further study included purification of PCR products and direct sequencing of PCR fragments by fluorescent end labeling. RESULTS: A C-to-T transition in codon 26 of exon 3 in the MYH7 gene was found in one family (including four patients and five carriers), resulting in an amino acid substitution of valine (Val) for alanine (Ala). The Ala26Val mutation was of incomplete dominance (penetrance 44%). This mutation was not seen in the other four families or in the control group. Moreover, the association between the gene mutations of exon 18 in MYH7, of exon 9 of TNNT2, and of all three exons in BNP and HCM was not found in the populations we studied. CONCLUSIONS: The missense mutation Ala26Val found in this one Chinese family was associated with a mild phenotype of HCM. The genetic and phenotypic heterogeneity of HCM exists in the Chinese population. It suggests that genetic and environmental factors may be involved in the pathogenesis of HCM.     

家族性肥厚型心肌病MYH7基因突变的筛查与分析

目的 研究家族性肥厚型心肌病(hypertrophic cardiomyopathy,HCM)的主要致病基因β肌球蛋白重链(beta-myosin heavy chain gene,MYH7)突变,并分析基因型与表型的关系.方法 对3个HCM家系成员的MYH7基因3～23号外显子及附近上下游序列采用DHPLC及直接测序分析.结果 在其中一个家系中发现MYH7基因14号外显子中存在Thr441Met突变,该突变曾经在一莱恩远端肌病患者中发现,而在中国人中是首次发现.另外两个家系也发现有不同位点的突变.结论 MYH7基因在HCM家系中具有较高的突变率,不同突变基因型以及基因突变携带个体在临床表型上有所差异.采取基因突变检测和分析,有利于HCM家族成员的诊断、患病风险预测及疾病早期预防和治疗.

Abstract：

Objective To detect gene mutations on beta-myosin heavy chain gene MYH7 in 3 Chinese families with hypertrophic cardiomyopathy ( HCM), and to analyze the correlation between genotype and phenotype. Methods A denaturing high-performance liquid chromatography (DHPLC) and sequencing mutation screening of the exons ( exon3-23 ) coding for MYH7 gene were performed in 3 Chinese families with HCM. Results In this study, we identified several mutations in MYHT. A mutation of Thr441 Met previously reported in a patient with Laing distal myopathy was first identified in one Chinese pedigree. Conclusion This study illustrated the high frequency of mutation in MYH7 gene in Chinese HCM families. Different mutations and carriers of the MYH7 gene present phenotypic heterogeneity. Mutation screening and analysis in HCM family could therefore facilitate the early HCM diagnosis and would be helpful for the prediction, prevention and early treatment of HCM linked with MYH7 gene mutation.     

心脏型肌球蛋白结合蛋白C基因13261 G＞A突变导致肥厚型心肌病的临床表型分析

目的研究中国人肥厚型心肌病致病基因,分析基因型与临床表型的关系。方法在一肥厚型心肌病家系中进行心脏型肌球蛋白结合蛋白C基因（MYBPC3）和β-肌球蛋白重链基因（MYH7）突变筛查,利用聚合酶链反应（PCR）扩增其功能区的外显子片段,双脱氧末段终止法测序。家系调查资料包括临床表现、体格检查、心脏超声和心电图。结果在该家系27例有血缘关系的研究对象中9例携带MYBPC3 13261 G〉A（G758D）突变,正常对照组同一位置未见异常。该突变位点是MYBPC3基因第23号外显子的甘氨酸突变为天冬氨酸,其中2例携带者发病,一例表现为心室扩大,左室射血分数减低等扩张型心肌病样表现,伴室间隔不对称肥厚,厚度为14mm,另外一例患者为典型的肥厚型心肌病表现。MYH7基因未发现突变。结论MYBPC3基因13261 G〉A突变是该肥厚型心肌病家系的致病突变,其外显率为22％,其中一例患者表现为肥厚型心肌病的扩张相,MYBPC3基因G758D突变可能是肥厚型心肌病进展为扩张型心肌病样改变的原因之一。对临床表现为扩张型心肌病的患者进行家族史调查及基因检查十分必要。     

中国汉族家族性肥厚型心肌病人群MYH7基因Arg723Gly突变分析

目的研究中国汉族人群家族性肥厚型心肌病的致病基因突变位点,分析基因型与表型的关系。方法对5个肥厚型心肌病家系的先证者进行β-肌球蛋白重链基因扫描,聚合酶链反应扩增其功能区的外显子片段,双脱氧末段终止法测序。对阳性结果患者进行家系调查,收集临床资料,分析其临床表型。结果在1个家系中发现Arg723Gly杂合突变,而正常对照组同一位置未见异常,此为我国患者中首次发现Arg723Gly突变。结论β-肌球蛋白重链可能是我国家族性肥厚型心肌病的常见致病基因之一。Arg723Gly所致肥厚型心肌病外显率高、临床症状出现较早、进展较快、易发生心力衰竭、预后较差,心脏室、房扩大也较常见,是一种恶性突变。     

Malignant mutations in hypertrophic cardiomyopathy: fact or fancy?

Hypertrophic cardiomyopathy (HCM) is a relatively common genetic disease, generally with a benign prognosis. However sudden cardiac death may occur, sometimes as the first manifestation of the disease. More than two hundred different mutations have been described in HCM, in 12 different genes encoding sarcomere proteins. This genetic diversity is accompanied by considerable clinical variability and it is likely that phenotype is partially determined by genotype. In recent years it has been suggested that genetic defects could be the major markers of prognosis. Thus, some mutations would carry a good prognosis whereas others, so-called 'malignant' mutations, would be associated with premature sudden death. In a Portuguese population of 35 index patients with HCM the authors found considerable genetic heterogeneity: seven of the 12 mutations identified were de novo, each family having its own 'private' mutation. Moreover, in two unrelated families with the same mutation (I263T--exon 9, missense) in the beta-myosin heavy chain gene (MYH7), penetrance, clinical expression and prognosis were quite different, particularly regarding the occurrence of sudden cardiac death. In two other also unrelated families, in each index patient a different mutation was identified in the troponin I gene (TNNI3): A157V (missense), exon 7 and S199N (missense), exon 8. Phenotypic expression was different but both patients suffered sudden cardiac death (one survived). This suggests that mutations in this gene carry an adverse prognosis. In conclusion, the considerable genetic and clinical variability found in HCM hinders the interpretation of genotype-phenotype correlations, particularly since all the published data is based on small numbers of families.     

Novel deletions in MYH7 and MYBPC3 identified in Indian families with familial hypertrophic cardiomyopathy

Mutations causing familial hypertrophic cardiomyopathy (HCM) have been described in at least 11 genes encoding cardiac sarcomeric proteins. In this study, three previously unknown deletions have been identified in the human cardiac genes coding for beta-myosin heavy chain (MYH7 on chromosome 14) and myosin-binding protein-C (MYBPC3 on chromosome 11). In family MM, a 3-bp deletion in MYH7 was detected to be associated with loss of glutamic acid in position 927 (DeltaE927) of the myosin rod. In two other families (HH and NP, related by a common founder) a 2-bp loss in codon 453 (exon 16) of MYBPC3 was identified as the presumable cause of a translation reading frame shift. Taken together 15 living mutation carriers were investigated. Six deceased family members (with five cases of premature sudden cardiac death (SCD) in families MM and NP) were either obligate or suspected mutation carriers. In addition to these mutations a 25-bp deletion in intron 32 of MYBPC3 was identified in family MM (five carriers) and in a fourth family (MiR, one HCM patient, three deletion carriers). In agreement with the loss of the regular splicing branch point in the altered intron 32, a splicing deficiency was observed in an exon trapping experiment using MYBPC3 exon 33 as a test substrate. Varying disease profiles assessed using standard clinical, ECG and echocardiographic procedures in conjunction with mutation analysis led to the following conclusions: (1) In family MM the DeltaE927 deletion in MYH7 was assumed to be associated with complete penetrance. Two cases of reported SCD might have been related to this mutation. (2) The two families, HH and NP, distantly related by a common founder, and both suffering from a 2-bp deletion in exon 16 of MYBPC3 differed in their average phenotypes. In family NP, four cases of cardiac death were documented, whereas no cardiac-related death was reported from family HH. These results support the notion that mutations in HCM genes may directly determine disease penetrance and severity; however, a contribution of additional, unidentified factors (genes) to the HCM phenotype can-at least in some cases-not be excluded. (3) The deletion in intron 32 of MYBPC3 was seen in two families, but in both its relation to disease was not unequivocal. In addition, this deletion was observed in 16 of 229 unrelated healthy individuals of the population of the South Indian states of Kerala and Tamil Nadu. It was not seen in 270 Caucasians from Russia and western Europe. Hence, it is considered to represent a regional genetic polymorphism restricted to southern India. The association of the deletion with altered splicing in transfected cells suggests that this deletion may create a "modifying gene", which is per se not or only rarely causing HCM, but which may enhance the phenotype of a mutation responsible for disease.     

心脏型肌球蛋白结合蛋白C基因IVS15-1G＞A突变导致肥厚型心肌病

目的研究中国人肥厚型心肌病（HCM）致病基因,分析基因型与临床表型的关系。方法在一HCM家系中进行心脏型肌球蛋白结合蛋白C基因（MYBPC3）和β-肌球蛋白重链基因（MYH7）突变筛查,利用聚合酶链反应（PCR）扩增其功能区的外显子片段,双脱氧末段终止法测序。家系调查资料包括临床表现、体格检查、心脏超声和心电图。结果在该家系8例有血缘关系的研究对象中6例携带MYBPC3（gi：Y10129）G8887A突变,正常对照同一位置未见异常。该突变位点是MYBPC3基因15内含子的剪接位点的受体位点（IVS15-1G〉A）,其中3例携带者发病,表现为轻微的胸闷、胸痛和不对称性室间隔轻度肥厚（13～14mm）,发病较晚（48～75岁）。MYH7基因未发现突变。结论MYBPC3基因IVS15—1G〉A突变是该HCM家系的致病突变,其携带者临床表型较好。对于症状轻微、发病较晚的HCM患者,首选MYBPC3基因进行突变筛查是较为合理可行的方法。