利用目标基因捕获结合第二代测序技术发现腹主动脉瘤致病基因突变

目的建立目标基因捕获结合第二代测序技术对腹主动脉瘤患者原纤维蛋白1(FBN1)基因进行突变筛查,探讨腹主动脉瘤与FBN1基因突变的关系。方法提取4例腹主动脉瘤患者外周血全基因组DNA,利用Gen Cap目标基因捕获技术,设计FBN1的65个外显子区域特异性捕获探针,与基因组DNA文库进行杂交,将目标基因组区域的DNA片段进行富集后,再利用Illumina Hi Seq2000第二代测序仪进行测序,通过数据分析,确定突变位点,用Sanger测序法对突变位点进行验证。结果设计合成的目标基因特异性捕获探针可有效地捕捉并富集基因组DNA的目标靶片段。4例患者目标区域平均测序深度为448.15~536.61,99.5%~99.7%目标区域覆盖度。经过数据分析及Sanger测序验证发现1个新的错义突变c.2753 CG(p.Pro918Arg),db SNP137数据库、千人基因组及内部800名正常汉族人数据库均无此突变。经SIFT预测为有害突变。结论本研究所建立的Gen Cap目标基因捕获技术结合Illumina Hi Seq2000第二代测序技术成功地发现了FBN1的新突变。该方法快速而有效,对腹主动脉瘤分子病因学有更好的认识。     

利用目标基因捕获结合二代测序技术发现左心室心肌致密化不全MYBPC3基因错义突变

目的:建立目标基因捕获结合第二代测序技术,对孤立性左心室心肌致密化不全(IVNC)患者的已知致病基因MYBPC3进行突变筛查。方法:收集5例IVNC患者及一级亲属的超声影像学资料,并提取外周血全基因组DNA,设计MYBPC3外显子区域特异性捕获探针,与基因组DNA文库进行杂交,富集目标基因组区域DNA片段,利用二代测序技术,确定突变位点,并使用Sanger测序法在其一代亲属中验证。结果:目标基因特异性捕获探针可有效地捕捉并富集基因组DNA目标靶片段。在5例IVNC患者中,发现1例MYBPC3基因杂合非同义突变c.G1000A(p.E334K),该突变位于MYBPC3基因第13外显子中,测序深度249.65。经过数据分析与Sanger测序验证后,父亲发现此突变位点,母亲未发现提示突变的父亲的遗传。结论:本研究所建立的Gen Cap目标基因捕获测序技术结合二代测序技术成功发现了MYBPC3基因突变。     

儿童马方综合征患者原纤维蛋白1基因突变与临床表型的相关性研究

目的:检测儿童马方综合征(MFS)患者原纤维蛋白1(FBN1)基因突变,探讨基因型和临床表型的相关性。方法:收集临床确诊或疑似MFS的儿童患者30例,试剂盒提取外周静脉血DNA,应用Ion AmpliSeq NGS Panel靶向目标测序技术(赛默飞),针对FBN1基因用AmpliSeq Panel扩增目的片段,进行磁珠纯化、链霉素标记,进行Ion PGM上机测序。对测序信息进行分析,确定突变位点,同时收集患者的临床表型信息,分析基因型和临床表型的相关性。结果:从上述患者中筛选出27例携带FBN1基因突变;主动脉Z评分≥3WV携带截短或者剪接突变的患者占70.0%,显著高于主动脉Z评分3组(70.0%vs. 23.5%,P0.05);携带半胱氨酸相关突变患者有更容易出现晶状体异位的趋势(P=0.119)。结论:儿童MFS患者FBN1基因型和临床表型存在诸多关联,这该疾病的诊断和治疗有一定参考价值。     

突变位点c.868C>T年轻的成年发病型糖尿病1型家系一例报道

报道1例突变位点为c. 868C>T,p. Arg290Cys的MODY1家系，分析其临床特点及分子遗传学特征。先证者使用目标序列捕获高通量测序技术检测致病基因，发现其携带肝细胞核因子4α基因突变，收集家系成员外周血基因组DNA，使用Sanger测序技术均检测到同一突变位点c. 868C>T的杂合变异。根据检测结果调整治疗方案，从而提高患者血糖达标率。     

目标基因捕获测序技术检测肺动脉高压致病基因突变的研究

目的:利用目标基因捕获测序技术,对9例肺动脉高压(PAH)患者进行4个已知致病基因突变筛查,探讨利用目标基因捕获测序技术对PAH进行基因诊断的可行性。方法:抽取PAH患者外周血,提取全基因组DNA,制备文库。设计骨形成蛋白2型受体(BMPR2)、激活素受体样激酶1(ACVR1)、细胞内皮糖蛋白(En G),信号蛋白SMAD4基因(SMAD4)外显子区域特异性捕获探计,利用目标基因捕获技术,进行杂交,富集目标基因组区域的DNA片段,利用Illumina Hi Seq 2000进行高通量测序,分析致病基因突变与PAH的相关性。结果:9例患者中,2例患者发现BMPR2基因突变,1例发现ACVRL1突变,BMPR2突变临床症状较重,ACVRL1突变发病年龄较小。结论:本研究利用目标基因捕获测序技术,在9例PAH患者中查出3个致病基因突变。该方法快速有效,可实现对PAH致病基因突变的初步筛查,对PAH的临床基因诊断具有重要价值。     

家族性血脂异常LPL基因新突变位点分析

目的:对收集的1例血脂异常家系的致病基因进行全外显子测序,确定其突变基因位点。方法:收集在我院就诊的1例血脂异常患者及其家系成员的临床资料,采集患者及相关家系成员外周血样本并提取基因组DNA,利用目标外显子捕获技术和二代测序技术对先证者的与血脂异常有关的基因进行基因突变筛查,并使用Sanger测序法验证可疑突变位点并筛查患者家系成员和100例健康人,确定该家系患者的致病突变基因,使用Polyphen2、MutationTaster、SIFT和Provean这4种软件进行突变基因功能检测,并利用Swiss-Model软件分析突变前后的蛋白质三维结构模型。结果:在受检人样品中检测到LPL基因的纯合变异c.1322+1GA(编码区第1322+1位核苷酸由G变为A),在其子女样品中检测到LPL基因同位点的杂合变异。4种预测软件均预测该突变为有害突变,Swiss-Model软件结果显示该突变位点导致442位的缬氨酸突变为终止密码子,可能影响蛋白质的剪切和活化功能。结论:本研究应用全外显子测序技术在一血脂异常家系中发现LPL基因新的突变位点:LPL c.1322+1GA。该突变可能是患者家系发生高三酰甘油血症的致病因素,且可能导致更严重的冠心病。此位点目前在我国人群中少见文献报道。     

一个新的肝细胞核因子1α仪基因突变致青少年的成人起病型糖尿病3型家系报道

目的探讨一个青少年的成人起病型糖尿病（MODY）家系的致病基因。方法对一例发病9年的32岁女性糖尿病患者家系成员进行调查,该家系中有两代糖尿病患者,采用目标区域捕获高深度测序技术在先证者中找到突变基因,使用Sanger测序技术验证突变位点并筛查其他家系成员。结果基因检测发现家系中3个个体携带肝细胞核因子1仅（HNF·1α）基因V380Cfs。39移码突变,该突变在家系中表现为与糖尿病共分离。结论该家系为一个新的HNF-1α仅基因突变所致MODY3家系。     

利用全外显子组测序技术发现Noonan综合征BRAF基因新生突变

目的:利用全外显子测序技术,对Noonan综合征(NS)患儿及父母进行测序,筛选致病基因突变,探讨基因型与临床表型的关系。方法:提取NS患儿及其父母外周血基因组DNA,使用Agilent Sure Select Human All Exome V6试剂盒进行全基因组外显子捕获,利用Illumina Hiseq X Ten测序仪进行双端高通量测序。通过生物信息学分析,利用db SNP数据库、千人基因组、Ex AC数据库分析变异频率,确定突变位点,用Sanger测序法进行验证。结果:患儿,女性,4岁1个月,生长发育落后、特殊面容。超声心动图示肺动脉瓣狭窄、卵圆孔未闭,临床未给予明确诊断。通过全外显子测序,在患儿BRAF基因中找到一个杂合错义突变c.770AG(p.Q257R),其父母此位点为正常基因型,该突变为患儿新发突变。结合临床表型和基因检测结果,该患儿最终被诊断为NS。结论:本研究明确了NS和突变位点的关系,强调了全外显子测序用于非典型病例明确诊断和准确遗传咨询的实用性。     

马凡综合征FBN1基因突变及基因型表型关联研究

目的本研究报道了一个马凡综合征家系的临床特征和致病基因筛查结果,同时探索了FBN1基因突变和临床表型间的关系。方法研究纳入1个MFS家系,经询问病史及检查,并对其基因组DNA进行了FBN1测序。结合既往研究的数据进行了基因型与表型关联分析。结果在先证者及家系成员中发现FBN1终止突变p.R565X,c.1693CT。基因型-表型分析发现,100%携带者有心血管系统累及(9/9),88.9%的携带者有骨骼系统的异常累及(8/9)。结论本研究报道了MFS家系的致病突变R565X。携带者容易出现心血管和骨骼病变,进行氯沙坦治疗可以延缓主动脉病变的进展。这些发现对马凡综合征的诊断和治疗有重要意义。     

FBN1基因钙结合转化生长因子结构域终止突变基因型表型研究

目的报道一个马凡综合征家系的临床特征和致病基因筛查结果,同时探索FBN1基因表皮生长因子结构域终止突变和临床表型间的关系。方法研究纳入1个马凡综合征家系,经询问病史及检查,并对其基因组DNA进行了FBN1基因测序。结合既往研究的数据进行了FBN1基因钙结合表皮生长因子结构域终止突变的基因型与表型关联分析。结果在马凡综合征先证者及其家系成员中发现FBN1基因8号表皮生长因子结构域(cb EGF-like#08)移码突变p.Glu768Valfs X6,c.2302_2309del GAATGTGT。结合以往研究报道的基因型-表型分析发现,发生于FBN1基因8号表皮生长因子结构域的终止(PTC)突变,100%携带者有心血管系统累及(5/5),80.0%的携带者有骨骼系统的异常累及(4/5)。结论研究报道了MFS家系的一个新的致病移码突变Glu768Valfs X6,携带者容易出现主动脉夹层及主动脉瘤。基因型表型分析发现,发生于FBN1基因钙结合表皮生长因子结构域的终止突变更容易出现主动脉根部扩张及主动脉夹层等严重心血管系统表型。这些发现对马凡综合征的诊断和治疗有重要意义。     

Prenatal diagnosis of Marfan syndrome by fetal echocardiography: A case report and review of cardiovascular manifestations

Neonatal Marfan syndrome (nMFS), phenotypically and genotypically distinct from the classical syndrome, is rarely diagnosed prenatally, and the cardiovascular prognosis is poor. This case report described one fetus diagnosed with nMFS by fetal echocardiography. The main features were cardiomegaly, and atrioventricular valves prolapse with moderate regurgitation and dilated great vessels. Extracardiac malformations included right diaphragmatic eventration, bilateral pyelectasis, and lengthy femur. Pathological examination confirmed the findings of fetal echo, and all cardiac valves were dysplastic. Sanger sequencing revealed a deletion mutation affecting exon 30 of the fibrillin 1 (FBN1) gene. Echocardiography is essential for prenatal diagnosis, and multivalve dysplasia is common among those patients.     

Molecular genetics of Marfan syndrome

PURPOSE OF REVIEW: Marfan syndrome, the founding member of connective tissue disorders, is characterized by involvement of three major systems (skeletal, ocular, and cardiovascular) due to alteration in microfibrils. FBN1 at 15q21.1 was found to cause Marfan syndrome in 1991, and in 2004 TGFBR2 at 3p24.1 was newly identified as the Marfan syndrome type II gene. Several studies implied that fibrillin-1 and transforming growth factor-beta (TGF-beta) signaling are functionally related in extracellular matrix. Identification of TGFBR2 mutations in Marfan syndrome type II provided the direct evidence of the relation in humans. RECENT FINDINGS: More than 500 FBN1 mutations have been found in Marfan syndrome, tentative genotype - phenotype correlations have emerged, and mouse models are providing insight into pathogenic mechanisms. TGFBR2 mutations are still limited, however, in 2005 were also reported to cause a new aneurysm syndrome. Functional association between fibrillin-1 and TGF-beta signaling in extracellular matrix has been presented. SUMMARY: This review focuses on recent molecular genetics advances in Marfan syndrome and overlapping connective tissue disorders. Mutation spectrum of FBN1 and TGFBR2 in relation to phenotype is presented. Functional relation between fibrillin-1 and TGF-beta signaling is discussed. Future prospects in the study of Marfan syndrome are presented.     

Target Gene Capture Sequencing in Chinese Population of Sporadic Parkinson Disease

Deciphering of genetic variants plays a critical role in research and clinic of genetic disorders, such as the well known neurodegenerative disease Parkinson disease (PD). To combine pool of targeted genes and next-generation sequencing (NGS), investigators could obtain high efficient but low-cost sequencing data of interested genes. Aim to discover genetic variants that might contribute to PD, we selected 48 candidate genes involved in different pathways and conducted a pilot study to screen nonsynonymous SNPs (nsSNPs) in 4 pooled samples from 237 sporadic Chinese PD patients. Using our custom-designed NimbleGen array and Illumina HiSeq2000, a total of 4 novel nsSNPs (c. 352G>T in STK39, c. 823G>T in DGKQ, c. 36T>A in DLA-DRB5, and c. 1981G>T in GRN) were discovered but not validated by Sanger sequencing. Additionally, we also selected 6 annotated nsSNPs without report in previous PD studies and validated by Sanger sequencing. However, genotyping analysis of 6 validated nsSNPs in 50 PD patients and 50 controls showed no significant differences in cases compared with controls. These data represent the first documentation and validation of these mutations in PD using target gene capture sequencing. Additional replication studies in other populations and functional research are merited to better evaluate precapture multiplex protocol and validate the role of the 6 nsSNPs in PD risk.     

Marfan Syndrome Type II: There Is More to Marfan Syndrome than Fibrillin 1

Marfan syndrome is a well‐described autosomal dominant syndrome with widely variable clinical manifestations. Cardiovascular complications include mitral valve prolapse with or without associated mitral valve insufficiency, aortic root dilatation, and most importantly the occasional development of aortic aneurysms or rupture. Given the inconsistent phenotype along with the potentially life‐threatening implications, clinicians are increasingly turning to genetic testing for definitive diagnostic confirmation. It has been well established that mutations in the FBN1 gene encoding the structural protein Fibrillin 1 is the molecular etiology of Marfan syndrome. However, there are numerous patients who meet the Ghent clinical diagnostic criteria for Marfan syndrome who do not have identifiable FBN1 mutations. Recently, mutations in TGFBR1 and TGFBR2 (transforming growth factor beta receptors 1 and 2, respectively) have been shown to result in Loeys–Dietz syndrome, a connective tissue disorder with significant phenotypic overlap with Marfan syndrome. Individuals with this Marfanoid disorder lack the ocular findings of Marfan syndrome and often have dysmorphic features such as unusual facies, cleft palate, and contractures. In addition, Loeys–Dietz syndrome patients often present in childhood with significant cardiovascular problems. This article serves to report an illustrative case of Loeys–Dietz syndrome and reviews the phenotypic consequences of FBN1 and TGFBR1 and TGFBR2 gene mutations.     

May TGFBR1 act also as low penetrance allele in Marfan syndrome?

Marfan syndrome, a human disease involving cardiovascular and skeletal apparatuses and ocular and central nervous systems, is associated to mutations in FBN1 gene; heterozygous mutations in TGFBR2 and TGFBR1 genes were found associated to MFS type 2, characterized by the presence of skeletal and cardiovascular major criteria and absence of eye major criterion. We screened the TGFBR1 gene in 46 Marfan patients in whom mutations in FBN1 and TGFBR2 genes were excluded and the analysis of Ex1 was extended to additional 114 Marfan patients and 237 controls. We detected two potentially pathological sequence variants: the TGFBR1 6Ala allele whose frequency was higher in the group of Marfan patients (0.13) than in the controls (0.08) (p=0.013; OR=1.69) and an insertion of 20 nucleotides in the 5'UTR that turned out to be a familial silent rare polymorphism. We hypothesize that TGFBR1 sequence variants may act not only as major, but also as low penetrance alleles of the clinical phenotype in Marfan syndrome.     

Indirect genotype analysis as a diagnostic procedure in Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant disorder of connective tissue characterized by skeletal, ocular and cardiovascular manifestations. The disease is caused by mutations in the FBN1 gene, encoding fibrillin, an important component of elastic fibers. Diagnosis of Marfan syndrome is currently based on detailed clinical examination and/or mutation analysis in the fibrillin gene. Clinical expression varies widely both among and within families, rendering clinical diagnosis extremely difficult. In this study, we performed segregation analysis of allelic DNA polymorphisms to support diagnosis of Marfan syndrome. This type of genotype analysis is a useful, additional diagnostic tool for families with Marfan syndrome and provides incremental information of diagnosis or exclusion of Marfan syndrome based on clinical findings.     

Coincidence of Andersen–Tawil syndrome and Marfan syndrome: A case report

We report on a 44‐year‐old woman with coincidence of two genetic disorders: Andersen–Tawil syndrome and Marfan syndrome. In both, life‐threatening arrhythmias could occur. A 44‐year‐old woman presented acute ascending aortic dissection with aortic arch involvement and chronic thoracic descending and abdominal aortic dissection. Clinical and genetic examination confirmed Marfan syndrome (MFS) diagnosis. Due to repolarization disorder in ECG and premature ventricular contractions in Holter ECG, the sequencing data were analyzed again and mutation in KCNJ2 gene was identified. The case showed that coincidence of Andersen–Tawil syndrome (ATS) and MFS did not provoke life‐threatening arrhythmias. Complication was rather caused by expression of FBN1 mutation.     

Badly engineered fibrillin lessons from molecular studies of marfan syndrome

Marfan syndrome (MFS) is one of the most common inherited connective tissue disorders that severely affects the cardiovascular system. Mutations in the gene encoding fibrillin-1 (FBN1) have been shown to cause MFS as well as dominant ectopia lentis and neonatal Marfan syndrome. Fibrillin-1 is the major component of elastic fiber microfibrils in the extracellular matrix of connective tissue. Recent molecular studies have brought some light into understanding the pathogenesis of MFS, but the diagnostic problems still prevail, and targeted therapy of MFS must await better dissection of the role of fibrillin-1 in tissue phenotype using different experimental systems. (Trends Cardiovasc Med 1997;7:282-288). © 1997, Elsevier Science Inc.     

Value of molecular diagnosis in a family with Marfan syndrome and an atypical vascular phenotype

Marfan syndrome is mainly caused by mutations in the FBN1 gene. Diagnosis is usually based on clinical criteria, but the phenotypic presentation varies widely among affected individuals. Aortic dissection or rupture is the cause of death in over 90% of untreated patients. Early identification of individuals at risk is important given the availability of medical and surgical treatment that can significantly improve life-expectancy. Molecular testing could provide an etiologic diagnosis in patients who present with milder or atypical clinical forms of the disease. Moreover, it could contribute to preventive treatment in carriers, inform genetic counseling and offer reassurance to unaffected individuals. By describing a family with Marfan syndrome in whom the disease presented in an atypical aggressive form, this article highlights the value of tests for detecting FBN1 mutations in selected cases.Full English text available from: www.revespcardiol.org