37例致心律失常性右心室心肌病患者PKP2基因检测

目的 调查单中心致心律失常性右心室心肌病(ARVC)患者PKP2突变发生率.方法 对50例考虑诊断为ARVC的患者采用2010年新诊断标准进行重新评估.采用聚合酶链式反应(PCR)扩增PKP2基因各外显子片段并测序,结果与200例正常对照组进行比对分析.结果 37例被确诊ARVC,9例为临界诊断,另4例为疑似诊断.确诊患者中有10例(27％)携带7个新突变和3个已报道突变,包括7个无义突变和3个错义突变,临界诊断及疑似诊断患者均未检测出PKP2基因突变.携带PKP2突变的患者与未携带突变的患者临床特征差异无统计学意义.结论 本组ARVC患者PKP2基因突变发生率与欧美国家相似,但突变谱存在差异.     

致心律失常性右室心肌病桥粒蛋白基因突变检测

目的致心律失常性右室心肌病(ARVC)为常染色体遗传性疾病,目前已经发现了与之相关的数个基因。大陆ARVC患者的致病基因筛查鲜有报道。方法本研究纳入2例家族性ARVC患者及10例散发的ARVC患者,提取其外周血DNA,设计DSP、PKP2、DSG2、DSC2和JUP/PG基因各外显子的引物,聚合酶链反应(PCR)扩增其功能区的外显子片段,直接测序,将测序结果与正常基因组进行比对以确定其突变位点。结果去除单核苷酸多态(sNF)后,12例ARVC患者中有5例存在基因突变:DSG2基因第8号外显子、第14号外显子存在错义突变位点;JUP基因第3号外显子存在同义突变位点、第5号外显子基因存在错义突变位点。结论中国ARVC人群的DSG2基因和JUP基因存在致病突变。     

Liddle综合征的基因诊断(附4例同胞兄弟上皮钠通道基因突变分析)

目的 Liddle综合征家系成员的基因突变分析。方法 一家系三代4例同胞兄弟均患高血压,其中2例经临床检验诊断为Liddle综合征。抽取三代所有成员的基因组DNA,用PCR法扩增上皮钠通道β及γ亚单位（βENaC,γENaC）第13外显子,直接DNA测序法进行基因突变检测。结果 βENaC基因第13外显子的DNA测序结果显示,4例患病同胞兄弟在该外显子的616号密码子均存在CCC→CTC错义突变,家系中其他成员均未发现基因突变。γENaC基因测序未发现突变。结论 同一个家系中的4例高血压同胞检出βENaC基因突变,在基因水平上确诊为Liddle综合征。     

中国致心律失常性右心室心肌病患者常见基因突变检测及临床分析

目的：确定中国致心律失常性右心室心肌病（ARVC）患者相关基因突变的患病率，并探索潜在的基因型-表型关系。方法：根据2010年修订的国际专家组的ARVC诊断标准，对32例有症状且临床诊断为ARVC的汉族患者的基因型和表型进行研究。结果：18例（18/32,56.3%）患者中发现了4个桥粒基因PKP2、desmoplakin(DSP)、desmoglein-2 (DSG2)、desmocollin-2(DSC2)中17个突变，包括6个新突变（6/17,35.3%）；非桥粒基因未发现突变。32例患者检测到的突变中，PKP2突变11例（11/32,34.4%）,DSP突变3例（3/32,9.4%）,DSG2突变3例（3/32,9.4%）,DSC2突变4例（4/32,12.5%）。5例（5/32,15.6%）患者出现多个突变。基因型-表型分析未显示携带突变患者与未携带患者的任何差别。结论：PKP2突变是本组ARVC队列中最常见的突变基因，在本研究中未发现非桥粒基因突变。     

分子遗传学检查诊断Crigler-Najjar综合征Ⅱ型3例

目的 探讨采用分子遗传学检查诊断Crigler-Najjar综合征Ⅱ型的方法。方法 在本科收治的3例高间接胆红素血症患者,抽取外周静脉血,提取基因组DNA,应用PCR法扩增尿苷二磷酸葡萄糖醛酸转移酶1A1基因（UGT1A1）所含5个外显子及其侧翼序列,进行DNA直接测序。结果 3例患者均检出UGT1A1基因5号外显子存在c. 1456 T>G（p.Y486D）纯合突变;Y486D位于第5外显子上,使1456位胸腺嘧啶（T）突变为鸟嘌呤（G）,导致486位氨基酸由酪氨酸（Tyr）变为天冬氨酸（Asp）。结论 当临床上高度怀疑Crigler-Najjar综合征Ⅱ型时,应尽早行分子遗传学检查,确定其基因突变位点,以明确诊断。     

变性梯度凝胶电泳分析检测结直肠癌APC和p53基因突变

目的: 探讨APC和p53基因突变在结直肠癌中的意义.方法:采用变性梯度凝胶电泳(DGGE), DNA测序法分析15例正常人和60例散发性结直肠癌标本的APC基因15外显子和p53基因第5, 7外显子的基因突变.结果: 在结直肠癌组检出14例APC和16例p53基因突变, 测序证实其中13/14例APC发生在突变集中区域;9/16例p53基因突变位于第5外显子, 7/16例p53基因突变位于第7外显子, 2例同时检出了APC基因和p53基因突变.结论:DGGE是一种快速、简便、高效、灵敏的突变检测技术. 同时也证明APC基因突变和p53基因突变均参与了结直肠癌的发生、发展过程.     

家族性高胆固醇血症患者低密度脂蛋白受体基因新的突变类型一例

目的：分析一例家庭性高胆固醇血症患的低密度脂蛋白受体基因突变位点。方法：以患儿的基因组DNA为模板，用聚合酶链反应（PCR）扩增该基因的18个外显子。用单链构象多态性（SSCP）方法分析检测PCR产物，对电泳结果异常进行DNA测序。结果：单链构象多态性分析发现患儿第10外显子存在一异常条带。DNA测序证实患儿第10外显子发生N515S纯合错义突变。结论：该病例为一个新的LDLR突变位点；聚合酶链反应－单链构象多态性分析（PCR－SSCP）可用于该突变位点的诊断。     

急性白血病BRAF癌基因突变研究

目的：探讨BRAF基因突变在急性白血病（AL）中的意义.方法：应用PCR、变性高效液相色谱（DHPLC）技术及DNA测序方法对22例AL患者进行BRAF基因外显子11～15突变检测.结果：1例患者外显子12扩增产物DHPLC出现额外色谱峰，测序结果显示在内含子12＋35位点G→C变异;其余样本各外显子均未见DHPLC改变.结论：AL中BRAF癌基因突变可能并不常见;内含子12变异的作用有待进一步研究。     

β肌球蛋白重链基因Asn391Thr突变导致家族性肥厚型心肌病的基因型与临床表型分析

目的研究家族性肥厚型心肌病（HCM）致病基因突变位点,分析基因型与临床表型的联系。方法利用靶向捕获加二代测序,对1个HCM家系的先证者进行26个致病基因的筛查。二代测序发现的突变,利用双脱氧末端终止法测序进行验证,并对家族中其他成员进行该突变位点的筛查,并分析其临床表型特点。结果遗传筛查发现先证者携带β肌球蛋白重链基因（MYH7）．c．1172A〉C（Asn391Thr）突变,该突变位于MYH7基因第12号外显子,导致β肌球蛋白重链的第391位氨基酸残基由天冬酰胺变为苏氨酸。该家系中接受调查的22例对象中8例携带MYH7基因Asn391Thr突变,其中6例患者均携带该突变,突变与疾病呈共分离,且在307名对照者中没有检出。携带者中有3例出现呼吸困难、心悸、胸痛、黑噱等心功能不全表现,所有患者发病年龄均小于40岁,其中Ⅱ9小于8岁（见图1）。家系中有4人早逝（〈50岁）,其中3人确诊为HCM。结论MYH7基因Asn391Thr错义突变为HCM的一个恶性致病突变,携带该突变的患者应进行较积极的治疗和猝死预防。     

DSP复合杂合基因突变与扩张型心肌病的发生有关

目的:通过全外显子测序寻找扩张型心肌病(dilated cardiomyopathy, DCM)家系的致病基因,分析临床特点及基因突变位点。方法:收集在本院就诊的1例DCM患儿的临床资料,采集患儿及其父母的外周血,抽提血液DNA,进行全外显子测序,寻找致病基因,Sanger测序验证可能的致病基因突变,对其临床特点、实验室检查、基因突变进行综合分析。结果:将测序结果比对分析,多个生物数据库筛选、过滤,发现桥粒斑蛋白(desmoplakin,DSP)基因c.939+1GA和c.4198CT位点发生突变。DSP可能是该家系DCM的致病基因,并且DSP基因第1 400位精氨酸残基在不同物种之间具有高度保守性。患儿左心房、左心室显著增大,左心室收缩功能减低(左心室射血分数为15%,左心室缩短分数为7%)。心电图提示窦性心动过速、心房肥大、T波改变(Ⅰ、V6导联T波倒置)。结论:DSP基因复合杂合突变(c.939+1GA和c.4198CT)与DCM紧密相关。分析临床特点与基因突变,对临床诊断心肌病提供依据。     

The other side of arrhythmogenic right ventricular cardiomyopathy

Knowledge regarding arrhythmogenic right ventricular cardiomyopathy (ARVC) has increased dramatically since the publication of the original International Task Force diagnostic criteria in 1994. Based on symptomatic index cases and sudden cardiac death victims, the Task Force criteria emphasized manifestations observed only at the most severe end of the clinical spectrum of ARVC. It is now known that the phenotypic expression of the disease may vary considerably both in its severity and in the pattern of myocardial involvement. Recent familial studies have emphasized that, despite its name, the abnormalities of ARVC are not limited to the right ventricle. In recognition of the prevalence and clinical significance of left ventricular involvement in ARVC, a proposed modification to the original International Task Force criteria was recently published. We herein describe 3 cases of patients with ARVC who presented with left ventricular involvement as manifested by nonischemic pattern of delayed enhancement in the left ventricle.     

Desmoglein-2 mutations in arrhythmogenic right ventricular cardiomyopathy: a genotype-phenotype characterization of familial disease.

AIMS: Mutations in the desmoglein-2 (DSG2) gene have been reported in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) but clinical information regarding the associated phenotype is at present limited. In this study, we aimed to clinically characterize probands and family members carrying a DSG2 mutation. METHODS AND RESULTS: We investigated 86 Caucasian ARVC patients for mutations in DSG2 by direct sequencing and detected eight novel mutations in nine probands. Clinical evaluation of family members with DSG2 mutations demonstrated penetrance of 58% using Task Force criteria, or 75% using proposed modified criteria. Morphological abnormalities of the right ventricle were evident in 66% of gene carriers, left ventricular (LV) involvement in 25%, and classical right precordial T-wave inversion only in 26%. Sustained ventricular arrhythmia was present in 8% and a family history of sudden death/aborted sudden death in 66%. CONCLUSION: Mutations in DSG2 display a high degree of penetrance. Disease expression was of variable severity with LV involvement a prominent feature. The low prevalence of classical ECG changes highlights the need to expand current diagnostic criteria to take account of LV disease, childhood disease expression, and incomplete penetrance.     

Ultrastructural evidence of intercalated disc remodelling in arrhythmogenic right ventricular cardiomyopathy: an electron microscopy investigation on endomyocardial biopsies.

AIMS: The ultrastructural features of the myocardium in arrhythmogenic right ventricular cardiomyopathy (ARVC) have not been systematically investigated so far. The recent discovery of gene mutations encoding intercalated disc proteins prompted us to perform a transmission electron microscopy study on endomyocardial biopsies. METHODS AND RESULTS: Twenty-one ARVC probands who fulfilled the international Task Force diagnostic criteria underwent right ventricular endomyocardial biopsy and screening of desmosome (D) protein encoding genes. Myocyte intercalated discs were analysed by transmission electron microscope and the data were compared with those of 10 controls and 10 patients with idiopathic dilated cardiomyopathy. Extensive fibro-fatty replacement with a residual myocardium of 59+/-23% was found in ARVC biopsy samples. Pathogenic D gene mutations were identified in 10 (48%): desmoglein-2 in four, desmoplakin in three and plakophilin-2 in three. Mean D length and D percent length of intercalated disc were significantly higher, D number was significantly lower and D gap was widened in ARVC. Moreover, abnormally located D in 75%, abnormal small junctions in 52%, and pale internal plaques in 32% of ARVC patients were found in the presence of a normal intercalated disc convolution index. CONCLUSION: The ultrastructural evidence of intercalated discs remodelling in ARVC, together with the positive screening of D protein encoding genes in half of probands, are in keeping with an intercellular junction cardiomyopathy.     

Relative Utility of Magnetic Resonance Imaging and Right Ventricular Angiography to Diagnose Arrhythmogenic Right Ventricular Cardiomyopathy

INTRODUCTION: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by fibrofatty replacement of the RV myocardium. Two imaging techniques used to assess patients suspected of having ARVC are magnetic resonance imaging (MRI) and right ventricular angiography (RVA). Traditionally, RVA has played a central role in the diagnosis of ARVC, but the non-invasive nature of MRI and its unique ability to detect fatty tissue infiltration has increased its popularity as a diagnostic tool. The objective of this study was to assess the relative diagnostic accuracy of MRI and RVA for ARVC. METHODS AND RESULTS: Seventeen patients (9 men, 8 women; ages 42 +/- 17 [range 16-78] years) with documented ventricular arrhythmias were investigated for ARVC. A positive diagnosis of ARVC was based on criteria set forth by the ISFC Working Group on Cardiomyopathies and Dysplasia. ECG-gated spin-echo and gradient-echo MR images in multiple planes and RAO/LAO RV angiograms were compared for diagnostic concordance. Based on working group criteria, 7 patients were diagnosed with ARVC. In ten patients, MRI suggested ARVC. The remaining 7 patients had no MRI findings suggestive of the disease. Four patients with MRI findings of ARVC were incorrectly diagnosed based on Task Force criteria. Conversely, 1 patient with a normal MRI met Task Force criteria for the diagnosis of ARVC. Based on RV angiograms, 7 patients had findings suggestive of ARVC. The 10 patients without AVRD (based on RVA) also did not meet the necessary criteria for diagnosis of ARVC using Task Force standards. RVA was 100% specific and 100% sensitive compared to MRI that was only 86% sensitive and 60% specific. MRI proved to be most reliable when the images demonstrated gross, lipomatous infiltration, evidenced by a large area of hyperintensity. When the results of MRI and RVA were congruent, the diagnosis was always accurate. CONCLUSION: RVA is more sensitive and specific to diagnose ARVC diagnosis than MRI, at least until MRI protocols are better developed. MRI results are most robust when indicators of ARVC are grossly apparent. False-positive diagnosis by MRI was primarily related to perceived motion abnormalities that were not seen by RVA. One of its greatest potential assets (fat detection) did not enhance diagnostic specificity.     

Composite polymorphisms in the ryanodine receptor 2 gene associated with arrhythmogenic right ventricular cardiomyopathy

OBJECTIVE: Mutations in the cardiac ryanodine receptor (RYR2) gene have been reported to cause arrhythmogenic right ventricular cardiomyopathy (ARVC). The molecular mechanisms by which genetic modifications lead to ARVC are still not well understood. METHODS: ARVC patients were screened for mutations in the RYR2 gene by denaturing HPLC and DNA sequencing. Single channel measurements were carried out with RyR2 channels purified from explanted hearts of ARVC patients. RESULTS: None of the published RYR2 mutations were found in our ARVC-cohort. However, we identified two single nucleotide polymorphisms (SNPs) in exon 37 of the human RYR2 gene which lead to the amino acid exchanges G1885E and G1886S, respectively. Both SNPs together were found exclusively in 3 out of 85 ARVC patients in a composite heterozygous fashion (genotype T4). This genotype was associated with ARVC (p<0.05) but not with dilated cardiomyopathy (DCM, 79 patients) or none-failing controls (463 blood donors). However, either one of the two SNPs were identified in further 7 ARVC patients, in 11 DCM patients, and in 64 blood donors. The SNP leading to G1886S may create a protein kinase C phosphorylation site in the human RyR2. Single channel recordings at pCa4.3 revealed four conductance states for the RyR2 of genotype T4 and a single open state for the wild type RyR2. At pCa7.7, the lowest subconductance state of the RyR2 channel of genotype T4 persisted with a greatly enhanced open probability indicating a leaky channel. CONCLUSION: The RyR2 channel leak under diastolic conditions could cause SR-Ca2+ depletion, concomitantly arrhythmogenesis and heart failure in a subgroup of ARVC patients of genotype T4. A change in the RyR2 subunit composition due to the combined expression of both SNPs alters the behaviour of the tetrameric channel complex.     

Arrhythmogenic right ventricular cardiomyopathy: From genetics to diagnostic and therapeutic challenges

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic disease characterized by myocyte loss and fibro-fatty tissue replacement. Diagnosis of ARVC remains a clinical challenge mainly at its early stages and in patients with minimal echocardiographic right ventricular (RV) abnormalities. ARVC shares some common features with other cardiac diseases, such as RV outflow ventricular tachycardia, Brugada syndrome, and myocarditis, due to arrhythmic expressivity and biventricular involvement. The identification of ARVC can be often challenging, because of the heterogeneous clinical presentation, highly variable intra- and inter-family expressivity and incomplete penetrance. This genotype-phenotype “plasticity” is largely unexplained. A familial history of ARVC is present in 30% to 50% of cases, and the disease is considered a genetic cardiomyopathy, usually inherited in an autosomal dominant pattern with variable penetrance and expressivity; in addition, autosomal recessive forms have been reported (Naxos disease and Carvajal syndrome). Diagnosis of ARVC relays on a scoring system, with major or minor criteria on the Revised Task Force Criteria. Implantable cardioverter defibrillators (ICDs) are increasingly utilized in patients with ARVC who have survived sudden death (SD) (secondary prevention). However, there are few data available to help identifying ARVC patients in whom the prophylactic implantation of an ICD is truly warranted. Prevention of SD is the primary goal of management. Pharmacologic treatment of arrhythmias, catheter ablation of ventricular tachycardia, and ICD are the mainstay of treatment of ARVC.     

Identification of sarcomeric variants in probands with a clinical diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC)

1 Aims

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by ventricular arrhythmias and sudden death. Currently 60% of patients meeting Task Force Criteria (TFC) have an identifiable mutation in one of the desmosomal genes. As much overlap is described between other cardiomyopathies and ARVC, we examined the prevalence of rare, possibly pathogenic sarcomere variants in the ARVC population.

2 Methods

One hundred and thirty‐seven (137) individuals meeting 2010 TFC for a diagnosis of ARVC, negative for pathogenic desmosomal variants, TMEM43, SCN5A, and PLN were screened for variants in the sarcomere genes (ACTC1, MYBPC3, MYH7, MYL2, MYL3, TNNC1, TNNI3, TNNT2, and TPM1) through either clinical or research genetic testing.

3 Results

Six probands (6/137, 4%) were found to carry rare variants in the sarcomere genes. These variants have low prevalence in controls, are predicted damaging by Polyphen‐2, and some of the variants are known pathogenic hypertrophic cardiomyopathy mutations. Sarcomere variant carriers had a phenotype that did not differ significantly from desmosomal mutation carriers. As most of these probands were the only affected individuals in their families, however, segregation data are noninformative.

4 Conclusion

These data show variants in the sarcomere can be identified in individuals with an ARVC phenotype. Although rare and predicted damaging, proven functional and segregational evidence that these variants can cause ARVC is lacking. Therefore, caution is warranted in interpreting these variants when identified on large next‐generation sequencing panels for cardiomyopathies.     

MR Imaging of arrhythmogenic right ventricular cardiomyopathy: morphologic findings and interobserver reliability

BACKGROUND: Magnetic resonance (MR) imaging is frequently used to diagnose arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). However, the reliability of various MR imaging features for diagnosing ARVC/D is unknown. The purpose of this study was to determine which morphologic MR imaging features have the greatest interobserver reliability for diagnosing ARVC/D. METHODS: Forty-five sets of films of cardiac MR images were sent to 8 radiologists and 5 cardiologists with experience in this field. There were 7 cases of definite ARVC/D as defined by the Task Force criteria. Six cases were controls. The remaining 32 cases had MR imaging because of clinical suspicion of ARVC/D. Readers evaluated the images for the presence of (a) right ventricle (RV) enlargement, (b) RV abnormal morphology, (c) left ventricle enlargement, (d) presence of high T(1) signal (fat) in the myocardium, and (e) location of high T(1) signal (fat) on a Likert scale with formatted responses. RESULTS: Readers indicated that the Task Force ARVC/D cases had significantly more (chi(2) = 119.93, d.f. = 10, p < 0.0001) RV chamber size enlargement (58%) than either the suspected ARVC/D (12%) or no ARVC/D (14%) cases. When readers reported the RV chamber size as enlarged they were significantly more likely to report the case as ARVC/D present (chi(2)(= )33.98, d.f. = 1, p < 0.0001). When readers reported the morphology as abnormal they were more likely to diagnose the case as ARVC/D present (chi(2) = 78.4, d.f. = 1, p < 0.0001), and the Task Force ARVC/D (47%) cases received significantly more abnormal reports than either suspected ARVC/D (20%) or non-ARVC/D (15%) cases. There was no significant difference between patient groups in the reported presence of high signal intensity (fat) in the RV (chi(2) = 0.9, d.f. = 2, p > 0.05). CONCLUSIONS: Reviewers found that the size and shape of abnormalities in the RV are key MR imaging discriminates of ARVD. Subsequent protocol development and multicenter trials need to address these parameters. Essential steps in improving accuracy and reducing variability include a standardized acquisition protocol and standardized analysis with dynamic cine review of regional RV function and quantification of RV and left ventricle volumes.     

Electrocardiographic and echocardiographic abnormalities in patients with arrhythmogenic right ventricular cardiomyopathy and in their pedigrees

Electrocardiographic and echocardiographic evaluations in 18 patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and 29 family members (25 males and 25 females from 7 pedigrees) aged 5 to 64 years (mean +/- 1 SD 30 +/- 16) revealed that 5 of 28 ARVC family members (17%) fulfilled ARVC Task Force criteria. Indexes on late potentials of the signal-averaged electrocardiogram had a significant linear correlation with the age of patients with ARVC and of family members with echocardiographic wall motion abnormality.     

C1抑制物基因突变提前形成终止密码子导致遗传性血管水肿

目的 检测7例来自不同遗传性血管水肿家系患者进行C1抑制物（C1 inhibitor,C1 INH）基因突变.方法 2011 至2012年北京协和医院变态反应科诊断为Ⅰ型HAE的7例来自不同HAE家系的先证者及53名健康成人为研究对象,采集外周静脉血,提取基因组DNA,聚合酶链反应扩增C1 INH基因的8个外显子及其相邻序列并进行序列检测.将检测结果与GenBank公布的C1 INH 基因序列相比较,确定突变及基因多态性.结果 7例患者C1 INH基因序列中均鉴定到致病突变,分别为c.289 CA,g.3248T〉C,g.3493T〉C,g.5755 G〉A,g.9498 T〉C,g.15193 A〉G,g.18012 G〉A.结论 本研究鉴定的7种不同C1 INH基因突变中有5种为国内外首次报道,丰富了中国C1 INH基因突变数据库.