心脏型肌球蛋白结合蛋白C与肥厚型心肌病

心脏型肌球蛋白结合蛋白C（cMYBPC）不仅参与正常肌小节和肌丝的组装，稳定肌小节的结构。而且通过磷酸化等调节横桥循环参与肌肉的收缩和舒张包括。编码肌小节结构蛋白的基因突变是家族性肥厚型心肌病的主要致病原因，其中编码cMYBPC的基因是肥厚型心肌病的最为常见的致病基因之一，本文就cMYBPC以及编码基因的结构、功能以及致病基因型、表型和可能的致病机制进行了较全面的阐述。     

心脏型肌球蛋白结合蛋白C基因缺失突变导致肥厚型心肌病特点分析

目的观察肥厚型心肌病（HCM）患者心脏型肌球蛋白结合蛋白C基因（MYBPC3）缺失突变及其表型的特点。方法在100例HCM患者中对MYBPC3的所有外显子及其侧翼内含子序列进行基因扫描,聚合酶链反应（PCR）扩增目的片段,双脱氧末段终止法测序。对突变患者进行家系调查,分析其表型特点。结果在两例先证者中分别发现两个缺失突变14262_14264delAAG和14364delG,均位于外显子25。表型分析发现两例先证者均有劳力性胸闷、胸痛和晕厥史,超声心动图表现为不对称性肥厚（室间隔/左室后壁分别为2.5、3.2）,但SAM征阴性,发病年龄分别为38岁和29岁。结论缺失突变是MYBPC3基因突变的常见形式,14262_14264delAAG或14364delG突变导致的HCM表现为不对称性心肌肥厚,患者容易出现晕厥等症状,应该警惕心源性猝死的发生。     

心脏肌球蛋白结合蛋白C基因1811518116insGCAGG突变导致肥厚型心肌病特点分析

目的观察肥厚型心肌病（HCM）患者中心脏肌球蛋白结合蛋白C基因（MYBPC3）插入突变的特点。方法在100例HCM患者中对MYBPC3的所有外显子及其侧翼内含子序列进行基因扫描,聚合酶链反应（PCR）扩增目的片段,双脱氧末段终止法测序。对突变患者进行家系调查,分析其表型特点。结果在一先证者及其一个家系成员中发现一个位于外显子29的五核苷酸插入突变（18115-18116ins-GCAGG）,序列分析发现1032位缬氨酸后发生了移码突变（p.Vall032fs）,造成先证者60岁发病,超声心动图上表现为室间隔重度不对称性心肌肥厚（35mm）。结论插入突变是MYBPC3基因突变的特点,18115-18116insGCAGG导致的HCM表型发病晚,心肌肥厚程度重。     

β-肌球蛋白重链及肌球蛋白结合蛋白C基因突变与肥厚型心肌病相关研究

原发性肥厚型心肌病（hypertrophic cardiomyopathy,HCM）是一种以左心室肥厚为主要病变的心肌病,常染色体显性遗传,是最常见的心血管遗传性疾病,约60％有明显的家族聚集性,称家族性肥厚型心肌病（FHCM）。     

心脏型肌球蛋白结合蛋白CG416S突变导致肥厚型心肌病

目的观察肥厚型心肌病(HCM)患者心脏型肌球蛋白结合蛋白CG416S突变导致肥厚型心肌病的特点。方法在100例HCM患者中对心脏型肌球蛋白结合蛋白C基因(MYBPC3)的所有外显子及其侧翼内含子序列进行基因扫描,聚合酶链反应(PCR)扩增目的片段,双脱氧末段终止法测序。分析携带基因突变患者的表型特点。结果在一例患者中发现MYBPC3第8697G>A基因突变,该突变位于外显子15,造成了心脏型肌球蛋白结合蛋白C第416位的甘氨酸转变成丝氨酸(G416S),该位置位于保守区。患者65岁时出现活动后胸痛不适,无高危因素。结论心脏型肌球蛋白结合蛋白CG416S错义突变能够导致HCM,携带该突变的患者表型轻、预后好。     

肥厚型心肌病肌球蛋白结合蛋白C基因突变研究

肥厚型心肌病（HCM）是以左心室和（或）右心室及室间隔非对称性肥厚为特征的一组疾病．属常染色体硅性遗传疾病．该病约有55％发病呈家旗聚集性。分子遗传学研究证实HCM是一种基因多态性疾病，编码肌小节结构蛋白的基因突变与其有关．数个基因中一个发生突变即可致病。目前，已发现了可以导致HCM的许多基因突变，包括编码可收缩肌小节的11个基因，超过200余种不同突变。     

心脏型肌球蛋白结合蛋白C基因18443A/G多态对肥厚型心肌病心肌肥厚程度的影响

目的探讨心脏型肌球蛋白结合蛋白C基因(Cardiac myosin binding protein c,MYBPC3)18443A/G多态对肥厚型心肌病(Hypertrophic cardiomyopathy,HCM)临床表型的影响.方法研究对象为在中国医学科学院阜外心血管病医院就诊的100例无血缘关系的HCM病人,120例性别、年龄匹配的健康人作为正常研究对照.设计特异引物,采用PCR扩增和直接测序法对MYB-PC3 18443A/G进行基因分型.结果携带MYBPC3 18443GG基因型的HCM患者肥厚心肌的厚度(24.3±7.3)mm大于携带AG基因型(20.0±5.3)mm(P<0.01)和AA基因型(17.4±2.8)mm(P<0.01)的HCM患者.未发现该多态与发病年龄、晕厥、心电图变化、左室舒张末平均内径、左房舒张末平均内径、收缩期二尖瓣叶前向运动等其他临床表型相关.结论MYBPC3不仅是HCM的主要致病基因,而且可能是影响心肌肥厚程度的修饰基因.     

中国肥厚型心肌病患者心脏型肌球蛋白结合蛋白C基因突变特点分析

目的观察中国肥厚型心肌病(HCM)患者心脏型肌球蛋白结合蛋白C基因(MYBPC3)突变的特点。方法在100例中国HCM患者中对MYBPC3基因的所有外显子及其侧翼内含子序列进行基因扫描,聚合酶链反应(PCR)扩增目的片段,双脱氧末段终止法测序。分析国人HCM患者基因突变的特点。结果 100例HCM患者中,10例患者携带9种MYBPC3基因突变,5种为错义突变,1种为剪接位点突变,1种为插入突变,2种为缺失突变。结论 MYBPC3基因是中国HCM人群的常见致病基因,并且MYBPC3基因突变形式多种多样,这是其主要的突变特点之一。     

心脏型肌球蛋白结合蛋白C基因突变导致肥厚型心肌病的表型特点

目的观察心脏型肌球蛋白结合蛋白C基因(MYBPC3)突变所致的肥厚型心肌病(HCM)的表型特点。方法既往研究中,我们筛查到10例患者携带9种MYBPC3基因突变,收集患者及其家系患者(6例)的临床资料,总结其表型特点。并且根据突变的类型分为两组:单个氨基酸的错义或缺失突变组、突变改变阅读框而表达截短蛋白组,比较其表型特点。结果 16例携带MYBPC3基因突变的HCM患者发病年龄为48.4±13.4岁,最大室壁厚度19.8±6.1mm,在单个氨基酸的错义或缺失突变组和突变改变阅读框而表达截短蛋白组两组之间无明显差别(发病年龄:47.4±12.4岁vs50.0±16.1岁;最大心室壁厚度:19.0±3.8mmvs21.0±9.2mm;P>0.05)。但3例有晕厥史的患者均见于后一组。结论 MYBPC3基因突变导致的HCM发病年龄较晚,多在中年后发病,室壁肥厚程度不重,与突变的类型无明显关系。但突变改变阅读框而表达截短蛋白组的患者更容易出现晕厥等恶性的表型。     

心脏肌球蛋白结合蛋白C基因Asp770Asn突变致肥厚型心肌病的表型研究

目的 研究心脏型肌球蛋白结合蛋白C基因(MYBPC3)Asp770Asn突变导致的肥厚型心肌病(hypertrophic cardiomyopathy,HCM)的临床特点,探讨该位点突变基因型与临床表型关系,为以基因型进行HCM危险分层提供依据.方法 在529例非亲缘关系肥厚型心肌病患者中进行panel测序筛查8个肌小...     

T445S:肥厚型心肌病的一个新的基因突变位点

目的调查中国人群肥厚型心肌病(HCM)患者心肌肌球蛋白结合蛋白C(MyBPC3)基因突变的发生情况并对基因型与表现型之间的关系进行分析。方法对92例肥厚型心肌病患者及100名正常对照的聚合酶链反应(PCR)扩增产物进行单链构象多态性分析(SSCP)分析,于MyBPC3基因第14-15、17、25、27、33号外显子范围内寻找突变位点,并了解基因型明确的HCM患者的临床特点。结果在一例HCM患者的MyBPC3基因的第14-15号外显子上发现了一个新的突变位点T445S。由于在100名正常对照中未见该错义突变,故我们认为此突变位点为该患者的致病基因位点。结论心肌肌球蛋白结合蛋白C的C3结构域对于其连接及调节功能起着至关重要的作用,该区域的基因突变可导致肥厚型心肌病的发生。     

Cardiac myosin binding protein-C modulates actomyosin binding and kinetics in the in vitro motility assay

The modulatory role of whole cardiac myosin binding protein-C (cMyBP-C) on myosin force and motion generation was assessed in an in vitro motility assay. The presence of cMyBP-C at an approximate molar ratio of cMyBP-C to whole myosin of 1:2, resulted in a 25% reduction in thin filament velocity (P < 0.002) with no effect on relative isometric force under maximally activated conditions (pCa 5). Cardiac MyBP-C was capable of inhibiting actin filament velocity in a concentration-dependent manner using either whole myosin, HMM or S1, indicating that the cMyBP-C does not have to bind to myosin LMM or S2 subdomains to exert its effect. The reduction in velocity by cMyBP-C was independent of changes in ionic strength or excess inorganic phosphate. Co-sedimentation experiments demonstrated S1 binding to actin is reduced as a function of cMyBP-C concentration in the presence of ATP. In contrast, S1 avidly bound to actin in the absence of ATP and limited cMyBP-C binding, indicating that cMyBP-C and S1 compete for actin binding in an ATP-dependent fashion. However, based on the relationship between thin filament velocity and filament length, the cMyBP-C induced reduction in velocity was independent of the number of cross-bridges interacting with the thin filament. In conclusion, the effects of cMyBP-C on velocity and force at both maximal and submaximal activation demonstrate that cMyBP-C does not solely act as a tether between the myosin S2 and LMM subdomains but likely affects both the kinetics and recruitment of myosin cross-bridges through its direct interaction with actin and/or myosin head.     

Functional Consequences of the Mutations in Human Cardiac Troponin I Gene Found in Familial Hypertrophic Cardiomyopathy

Functional consequences of the six mutations (R145G, R145Q, R162W, DeltaK183, G203S, K206Q) in cardiac troponin I (cTnI) that cause familial hypertrophic cardiomyopathy (HCM) were studied using purified recombinant human cTnI. The missense mutations R145G and R145Q in the inhibitory region of cTnI reduced the intrinsic inhibitory activity of cTnI without changing the apparent affinity for actin. On the other hand, the missense mutation R162W in the second troponin C binding region and the deletion mutation DeltaK183 near the second actin-tropomyosin region reduced the apparent affinity of cTnI for actin without changing the intrinsic inhibitory activity. Ca(2+) titration of a fluorescent probe-labeled human cardiac troponin C (cTnC) showed that only R162W mutation impaired the cTnC-cTnI interaction determining the Ca(2+) affinity of the N-terminal regulatory domain of cTnC. Exchanging the human cardiac troponin into isolated cardiac myofibrils or skinned cardiac muscle fibers showed that the mutations R145G, R145Q, R162W, DeltaK183 and K206Q induced a definite increase in the Ca(2+)-sensitivity of myofibrillar ATPase activity and force generation in skinned muscle fibers. Although the mutation G203S also showed a tendency to increase the Ca(2+) sensitivity in both myofibrils and skinned muscle fibers, no statistically significant difference compared with wild-type cTnI could be detected. These results demonstrated that most of the HCM-linked cTnI mutations did affect the regulatory processes involving the cTnI molecule, and that at least five mutations (R145G, R145Q, R162W, DeltaK183, K206Q) increased the Ca(2+) sensitivity of cardiac muscle contraction.     

心脏起搏治疗肥厚型梗阻性心肌病5年随访

目的：观察右心室起搏对肥厚型梗阻性心肌病（ＨＣＭ）患者的远期临床、血液动力学及形态学变化,以确定右心室起搏对其治疗效果及预后影响。 方法：对３０例ＨＣＭ患者采用有创血液动力学监测及多普勒超声心动图方法观察右心室起搏前及５年后患者的血液动力学及形态变化。 结果：右心室起搏５年后临床症状、心功能、血液动力学及超声心动日均显著改变,尤其二尖瓣收缩期前向运动（ＳＡＭ）、左心室流出道宽度、左心室流出道压力阶差（ＬＶＯＴＧ）、左心室舒张末期压、心排血量及心脏指数改善更为显著（Ｐ＜０．００１）,肥厚的心室间隔显著变薄（Ｐ＜０．０５）。 结论：右心室起搏能显著地改善患者的临床症状,心功能及血液动力学,其远期疗效显著,并发现能逆转肥厚的心室间隔及左心室游离壁,改善左心室流出道梗阻。因此为ＨＣＭ的起搏治疗提供了客观依据、对药物治疗无效或疗效不满意的患者,起搏治疗可能成为较理想的治疗措施。     

Differentiation of Cardiac Amyloidosis and Hypertrophic Cardiomyopathy

ABSTRACT. Eriksson P, Backman C, Eriksson A, Eriksson S, Karp K, Olofsson B-O (Departments of Internal Medicine, Geriatric Medicine, and Clinical Physiology, University Hospital, Umeå, and Institute of Forensic Medicine, University of Umeå, Umeå, Sweden). Differentiation of cardiac amyloidosis and hypertrophic cardiomyopathy. A comparison of familial amyloidosis with polyneuropathy and hypertrophic cardiomyopathy by electrocardiography and echocardiography. Acta Med Scand 1987; 221:39–46. The clinical and echocardiographic features of cardiac amyloidosis may closely resemble those of hypertrophic cardiomyopathy, and the disorders may thus be mixed up. The present study was undertaken in an attempt to identify features separating the two conditions by analysis of electro- and echocardiographic findings in patients with familial amyloid polyneuropathy and hypertrophic cardiomyopathy. Twenty-nine patients with familial amyloidosis and 22 with hypertrophic cardiomyopathy were studied. Particular attention was given to (1) the sum of the S wave in V₁ and R wave in V₅ or V₆, (2) the echocardiographic left ventricular mass and (3) cross-sectional area, the presence or absence of (4) asymmetrical septal thickening, (5) granular and sparkling myocardial appearance, (6) thickened heart valves, (7) systolic anterior motion of the mitral valve, and (8) pericardial effusion. A granular and sparkling appearance of the myocardium and thickened heart valves were found to be the best predictors of cardiac amyloidosis, while low QRS amplitudes in relation to echocardiographic left ventricular mass and a pericardial effusion seemed less important. The presence of systolic anterior movement of the mitral valve, a large left ventricular mass and a sum of S in V₁ and R in V₅ or V₆ >35 mm indicated hypertrophic cardiomyopathy. When the four strongest predictors (left ventricular mass, thickened heart valves, a granular sparkling myocardial appearance, and systolic anterior movement of the mitral valve) were used to reclassify the present patients, 28 of 29 amyloidosis patients and 21 of 22 patients with hypertrophic cardiomyopathy were correctly categorized. Noninvasive methods may thus be useful for detecting the myocardial infiltrative process, and cardiac amyloidosis may be confidently diagnosed by typical noninvasive findings together with histopathological documentation of amyloid in an organ other than the heart.     

血清心脏肌球蛋白结合蛋白C检测在急性心肌梗死患者诊断中的作用

目的探讨血清心脏肌球蛋白结合蛋白C(c My BP-C)在急性心肌梗死(AMI)患者诊断中的价值。方法选择2014年3月至2015年11月心血管内科收治的AMI患者62例作为病例组,选取正常体检者60例作为对照组。采用双抗体夹心酶联免疫吸附试验(ELISA)法检测血清c My BP-C浓度。比较AMI组与对照组间c My BP-C、肌钙蛋白Ⅰ(c TnⅠ)、肌酸激酶同工酶(CK-MB)和肌红蛋白(Myo)浓度的差异,分析AMI组c My BP-C与c TnⅠ、CKMB和Myo的相关性,同时分析发病时间小于4 h的AMI患者入院时血清c My BP-C和c TnⅠ浓度与对照组的差异,比较急诊经皮冠状动脉介入(PCI)术后12 h与入院时血清c My BP-C和c TnⅠ的差异。结果 AMI组患者血清c My BP-C、c TnⅠ、CK-MB和Myo浓度较对照组均明显升高(P0.05)。相关性分析显示,AMI组患者c My BP-C浓度与c TnⅠ、CK-MB和Myo浓度均存在正相关(分别为r=0.876、P0.05;r=0.632、P0.05和r=0.903、P0.05)。发病时间小于4 h的AMI患者入院时血清c My BP-C浓度较对照组明显升高(P0.05),而血清c TnⅠ浓度与对照组比较差异无统计学意义(P0.05)。行急诊PCI术后12 h血清c My BP-C浓度较入院时明显下降,而c TnⅠ浓度较入院时明显升高(P0.05)。结论 AMI患者入院时血清c My BP-C、c TnⅠ、CK-MB和Myo浓度较对照组均显著升高且c My BP-C浓度与c TnⅠ、CK-MB和Myo浓度均存在正相关;c My BP-C在发病4 h内即开始升高,提示c My BP-C可以作为诊断AMI的早期生化标志物。AMI患者行急诊PCI术后12 h血清c My BP-C浓度较入院时明显下降,表明c My BP-C可以作为评估PCI术效果的早期指标。