一个马凡综合征家系FBN1基因突变筛查

目的通过对临床上符合马凡氏综合征(MFS)临床诊断的患者进行分析并提供客观实验室依据,并对MFS患者家系进行FBN1基因突变筛查,希望发现这个家族的致病基因突变和基因突变位点,并探寻该家系的分子发病机制。方法收集MFS患者资料,绘制家系图谱,签署知情同意书后分别采取家系成员中与先证者有血缘关系的人群的外周静脉血血样,提取基因组DNA,进行全外显子测序,再采用Sanger测序法验证。结果通过基因突变筛查,发现该家系中患者的FBN1基因第58个内含子(序列NM-00138.4)出现一个新的7204+1GA的碱基杂合替换,该突变为剪接突变可能引起剪接位点改变。结论发现的FBN1基因第58个内含子(序列NM-00138.4)的剪接突变是该马凡氏综合征家系成员的患病原因。     

一例Ⅰ型成骨不全家系的基因定位及突变检测

目的 对国内1例成骨不全(OI)家系进行基因突变及突变效应分析,为研究中国人群的成骨不全基因突变特点提供线索.方法 对成骨不全Ⅰ型胶原基因COL1A1和COL1A2所在的17号染色体和7号染色体分别进行连锁分析,对致病基因做初步判断,然后用聚合酶链反应扩增致病基因外显子,并测序检出基因突变.结果 该家系为COL1A1基因突变,所有患者在该基因的第8个内含子剪切受体位点处为AG→GG(IVS8-2A＞G)突变.结论 对比COL1A1基因突变数据库,该突变为一新发现突变.     

遗传性对称性色素异常症一家系基因突变分析

目的 研究发现一家系遗传性对称性色素异常症的致病基因突变情况.方法 收集临床患者家系成员血样并抽提基因组DNA,通过PCR及突变检测致病基因的方法,分析基因的突变位点.结果 该家系患者DSRAD基因12号外显子发生基因突变,表现为第2887位G缺失.结论 该遗传性对称性色素异常症家系患者中存在致病基因突变,表现为碱基缺失.     

一个中国Gilbert综合征家系的临床和遗传学特征分析

目的 通过对1个中国Gilbert综合征家系成员临床特征分析,结合致病基因尿苷二磷酸葡萄糖醛酸转移酶1A1(UGT1A1)基因已知突变位点鉴定,了解该病临床发病特点和分子遗传学基础.方法 在长期追踪先证者基础上,抽取先证者及其家系成员外周血,进行肝脏生化学、病原学和UGT1A1基因突变位点检测,排除相关疾病,PCR扩增启动子和外显子常见突变位点,产物直接测序鉴定基因型.结果 在该家系中,检测到3个突变位点:c.-3279T＞G、TA插入和Gly71Arg,并且C.-3279T＞G和TA插入存在连锁不平衡,其中4例患者中3例为杂合突变,1例为纯合突变,胆红素水平与UGT1A1基因型和表型相关.结论 c.-3279T＞G、TA插入和Gly71Arg突变可能与中国人群Gilbert综合征发生相关,该家系基本符合常染色体隐性遗传方式.     

近亲结婚1家系Leber先天性黑矇TULP1基因新突变

目的 检测近亲结婚Leber先天性黑矇(LCA)家系致病基因突变。方法 选择近亲结婚Leber先天性黑矇家系作为研究对象,收集家系成员眼科检查资料和病史,采集外周静脉血,提取DNA。先证者采用全基因组外显子测序技术进行致病基因突变筛查;通过生物信息学分析后得到候选致病突变位点。运用Sanger测序进行验证及家系共分离分析,确定致病性突变位点。结果 基因检测在先证者TULP1基因(MIM#602280)第11号外显子检测到新的纯和错义突变c.C1024G(p.R342G),编码区第1024位的核苷酸C(胞嘧啶)变异为G(鸟嘌呤),变异导致编码蛋白序列内的氨基酸改变p.R342G,第342号氨基酸由精氨酸(Arg)变异为甘氨酸(Gly)。342号氨基酸位点在不同物种间具有高度保守性。生物学信息预测提示为致病性。结论 TULP1基因纯和错义突变c.C1024G:p.R342G是该家系的致病原因。该纯合突变国内外均未见报道,是一种新发现的LCA致病基因突变。本研究扩大了LCA基因突变谱,为LCA基因治疗及发病机制研究提供了依据。     

一例Ⅰ型成骨不全家系的基因定位及突变检测

目的对国内1例成骨不全(OI)家系进行基因突变及突变效应分析,为研究中国人群的成骨不全基因突变特点提供线索。方法对成骨不全Ⅰ型胶原基因COL1A1和COL1A2所在的17号染色体和7号染色体分别进行连锁分析,对致病基因做初步判断,然后用聚合酶链反应扩增致病基因外显子,并测序检出基因突变。结果该家系为COL1A1基因突变,所有患者在该基因的第8个内含子剪切受体位点处为AG→GG(IVS8-2A>G)突变。结论对比COL1A1基因突变数据库,该突变为一新发现突变。     

蒙古族并指一家系临床特点及其HOXD13基因突变检测

目的: 探讨先天性并指畸形一大家系的临床特点及其致病基因突变分析,为该类疾病的产前诊断以及携带者筛查提供依据。方法: 通过家系调查,对家系患者进行临床表型分析并进行手和脚部X光检查;绘制系谱图,整理分析家系资料;采集家系成员外周血并提取基因组DNA;通过外显子测序方法筛选候选基因,将捕获的候选基因突变位点进行PCR扩增后Sanger测序验证分析。结果: 该家系已传4代,并指患者共9例,其中男4例,女5例,Ⅰ2、Ⅱ4、Ⅲ5,7,10等5例患者为单侧并指,Ⅲ16和Ⅳ3,6,7等4例患者为双侧手指并指,脚趾均为正常。先证者及其家系患者均为HOXD13基因的第二外显子917位点发生G>A的突变,导致306位氨基酸从精氨酸到谷氨酰胺的改变,即c.917G＞A（P.R306Q）。家系正常成员均无此突变。结论: 该先天性并指家系属于常染色体显性方式遗传,HOXD13,c.917G＞A（p.R306Q）基因突变位点是该并指家系的致病突变。该家系Ⅲ12成员表型正常但致病基因携带者,表明该家系存在不完全外显特点。     

3个全面性癫痫伴热性惊厥附加症家系的遗传学研究

目的 分析全面性癫痫伴热性惊厥附加症家系的临床表型并筛查基因突变情况。 方法 收集先证者及其家系成员临床资料及外周血DNA，对患儿外周血进行包含全部目前已知癫痫相关致病基因的Illumina HiSeq 2000系列高通量全基因组测序筛查，如发现可疑突变基因，再对患儿家系其他成员进行该突变基因位点验证。 结果 3个家系中有9例受累者，受累者的临床表型包括3例热性惊厥(febrile seizures，FS)，3例热性惊厥附加症(febrile seizures plus，FS+)，2例无热全面强直阵挛发作(afebrile generalized tonic-clonic seizures，AGTCS)，1例热性惊厥附加症伴儿童失神，基因筛查发现家系1先证者及受累者父亲同时有2个基因突变，SCN5A和ABCC6基因，SCN5A为第28号外显子错义突变(c.G5239A)，ABCC6为10号外显子(c.1338+1G>A)的剪切位点变异。未受累者爷爷有SCN5A基因突变，受累者奶奶有ABCC6基因突变，另2个家系未发现可疑致病基因。 结论 本研究发现1个未报道的可疑致病基因ABCC6，未发现已经报道的致病基因突变，进一步证明GEFS+家系是多基因遗传病，遗传机制复杂，病因学有待大样本、大家系进一步研究。      

常染色体显性遗传性听神经病家系全外显子组测序分析

目的：在多年围绕1个常染色体显性遗传性非综合征型听神经病家系开展系统分子遗传学研究的基础上,进一步探讨该家系耳聋的致病机制,以期发现新的听神经病致病基因和突变位点。方法：对3例耳聋患者和1例配偶进行全外显子组测序,初步筛选出与家系耳聋相关的候选致病基因。采用PCR-Sanger测序法,检测上述候选基因变异是否与家系表型共分离。最后,以50例与研究家系无关的听力正常人为对照,检测候选致病突变在正常群体中的突变频率和SNPs遗传多态性。结果：全外显子测序分析得到41个候选致病基因突变;用PCR-Sanger测序法对核心家系的9名成员和2名家系外听力正常人进行验证,仅发现1个基因突变（ALOX15B 7942797 C>T）与家系耳聋表型共分离。选取50例家系外正常对照的DNA样本对ALOX15B基因进行PCR扩增和序列分析,结果显示有2例听力正常人也检测到该基因的同一变异,提示该变异为SNPs遗传多态性。结论：对核心家系成员的全外显子组测序分析和Sanger测序法验证未发现有意义的突变位点,排除了该家系耳聋由基因编码区突变及Indels致病的可能性。     

成骨不全症家系基因突变位点的检测

目的检测一I型成骨不全症家系中4例患者的基因突变位点。方法收集该家系患者外周血标本及健康人对照外周血标本,采用聚合酶链式反应、直接测序对COL1A1基因突变位点检测。结果该家系中成骨不全患者均存在COL1A1基因第23号外显子上一处G-C突变,在家系内非患者及正常对照者均未发现该突变。结论本研究为I型成骨不全的突变位点提供了新的证据,为进一步讨论COL1A1基因型和成骨不全临床分型之间的关系提供了研究基础。     

Marfan综合征FBN1基因新的剪接位点的置换突变

目的 对Marfan综合征(MFS)患者的原纤维蛋白-1基因(FBN1)进行突变筛查,探讨MFS患者新的FBN1突变.方法 应用聚合酶链反应(PCR)和变性高效液相色谱法(DHPLC)对1例MFS患者FBN1的65个外显子进行突变筛查,对DHPLC图形异常的PCR扩增片段用DNA测序鉴定突变位点及性质.用限制性片段长度多态性分析法(RFLP)进一步证实突变.结果 发现1种新的FBN1剪接位点的置换突变(Intron29 4A＞T).结论 FBN1的Intron29 4A＞T可能为该MFS患者的发病原因.     

Missense mutations of the fibrillin-1 gene in two Chinese patients with severe Marfan syndrome

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Identification of a novel lethal fibrillin-1 gene mutation in a Chinese Marfan family and correlation of 3’ fibrillin-1 gene mutations with phenotype

Background Mutations in the fibrillin-1 gene have been identified in patients with Marfan syndrome （MFS）. This study aimed to identify the molecular defects in the fibrillin-1 gene in a Chinese family with Marfan syndrome, accompanied by aortic aneu rysms/dissection. Methods Two patients and one non-carrier in the family underwent complete physical, ophthalmic, and cardiovascular examinations. Genomic DNA was extracted from leukocytes of venous blood of these individuals in the family as well as 50 healthy normal controls. Polymerase chain reaction amplification and direct sequencing of all 65 coding exons of fibrillin-1 gene were analyzed. Results We found a novel mutation （c.8547T〉G, p.Tyr2849X） in exon 65 of fibrillin-1 gene in a Chinese proband with Marfan syndrome, accompanied by aortic aneurysms/dissection. Sudden death at a young age of affected members was seen due to aortic aneurysms/dissection. By evaluating genotype-phenotype correlations of patients with mutations in the 3＇ end of fibrillin-1 gene （exons 64 and 65）, we also found that the presence of nonsense mutations occurring in exons 64 and 65 appeared to be an indicator of early-onset aortic risk and sudden death. Conclusions These results expand the mutation spectrum of fibrillin-1 gene and help in the study of the molecular pathogenesis of Marfan syndrome, indicating that mutations occurring in the 3＇ end of fibrillin-1 gene may play an independent functional role in the pathogenesis of Marfan syndrome.     

Molecular analysis for diagnosis of Marfan syndrome and Marfan-associated disorders

Marfan syndrome is a systemic disorder of connective tissue, caused by mutations in the FBN1, TGFBR1 or TGFBR2 genes. This syndrome is characterized by involvement of three major systems, skeletal, ocular, and cardiovascular. The continuing improvements in molecular biology and increasing availability of molecular diagnosis in clinical practice allow recognition of Marfan syndrome in patients with incomplete phenotypes. Additionally, molecular analyses could also be used for preimplantation genetic diagnosis. The identification of a mutation allows for early diagnosis, prognosis, genetic counseling, preventive management of carriers and reassurance for unaffected relatives. The importance of knowing in advance the location of the putative family mutation is highlighted by its straightforward application to prenatal and postnatal screening.

     

FBN1 mutation in Chinese patients with Marfan syndrome and its gene diagnosis using haplotype linkage analysis

Objectives To analyze the FBN1 mutations in Chinese patients with Marfan syndrome (MFS) and to make a genetic diagnosis based on haplotype linkage analysis for MFS.Methods Nine MFS families (17 patients) were analyzed with single strand conformation polymorphism (SSCP) and sequencing. Four primers were designed for the flanking sequences of FBN1 gene and used for haplotype-segregation analysis of MFS (B).Results SSCP band alteration was detected in the PCR products for exon 25 in MFS(A) Ⅱ : 1.Direct sequencing revealed a small 13 bp deletion; the deleted sequence is gccTcTgcaccca at bases 3243 -3456 of the cDNA in exon 25. This mutation was novel. MFS(B) families were analyzed using the haplotype linkage technique. The data suggested that MFS(B) families were linked to the FBN1 gene. The proband‘ s daughter was an asymptomatic patient.Conclusion The combination of mutation detection and chromosome haplotype analysis can provide better evidence for a genetic diagnosis of MFS.     

Challenges in the diagnosis of Marfan syndrome

Marfan syndrome (MFS) is a multisystem disorder of connective tissue that is inherited in an autosomal dominant fashion, and results from mutations in the FBN1 gene on chromosome 15. Diagnosis is challenging as it requires definition of diverse clinical features and input from a variety of specialists. Genetic testing of FBN1 is time consuming, expensive and complex, and may not solve the diagnostic dilemma. Failure to make a diagnosis or making an inappropriate diagnosis of MFS has social, lifestyle and medical consequences for the individual as well as the family.     

低钾周期性麻痹家系CACNA1S基因突变的研究

目的低钾周期性麻痹(hypokalemic periodic paralysis,HoKPP)是一种由于离子通道功能异常引起的疾病,呈常染色体显性遗传。文中筛查HoKPP家系患者的基因突变位点,为产前基因诊断提供实验依据。方法报告1个具有4代18例患者的HoKPP中国家系。提取HoKPP患者、家系中健康人以及100例无血缘正常对照血样中白细胞基因组DNA,应用PCR和DNA测序进行候选基因突变分析,包括骨骼肌二氢嘧啶敏感性钙通道α1亚单位(CACNA1S)基因和骨骼肌钠通道α亚单位基因(SCN4A)。结果分子遗传学研究显示该HoKPP家系所有患者CACNA1S基因外显子30上均存在杂合突变(G3716A),推测导致氨基酸序列改变(R1239H),家系中健康人以及无血缘正常对照组中均未见患者所携带的杂合突变位点(G3716A)。结论 CACNA1S基因的R1239H突变是该HoKPP家系发病的分子遗传学基础,可行产前基因诊断预防患儿出生。     

微纤维元基因突变导致以心血管及眼部症状为主的马凡综合征

目的 研究微纤维元基因（FBN1）突变引起的以心血管及眼部症状为主的家族性马凡综合征（Marfan‘s syndrome,MFS)的特点。方法 首先对4代（共计50例）家庭成员进行体检,筛选出有症状的个体及无症状的个体。采用单链构象分析（SSCA)方法对50例个体FBN1基因外显子进行筛选。在FBN1基因的65个外显子中,共计筛选了21个外显子。在确定外显子18SSCA异常后,对外显子18的扩增标本进行直接突变检测。结果 按照最新诊断标准26例被诊断患有MFS。分子生物学检测发现这个家族中FBN1基因外显子18有SSCA异常。结果显示所有临床上受累的个体都有同样形式的SSCA异常,然而临床上无症状的个体及外性配偶无一检出SSCA异常。在检测出SSCA异常后,对先症者（第一个发现患者MFS的人）及其患病的堂史的外显子18扩增片段,行直接突变检测,发现外显子754号密码上半胱氨酸替代了酪氨酸（Y754C）。结论 MFS为常染色体显性遗传。这个MFS家族携带FBN1突变,该突变导致以心血管及眼部症状为主的临床表现。临床拟表型各异,说明基因突变的表达受许多因素干扰。     

A new mutation of PTCH gene in a Chinese family with nevoid basal cell carcinoma syndrome

Background Nevoid basal cell carcinoma syndrome （NBCCS） is a rare autosomal dominant disease characterized by a combination of development anomalies and a predisposition to tumour formation. Mutation of patched gene （PTCH）, considered the molecular defect of NBCCS, in a Chinese NBCCS family was investigated in this study.
Methods Genomic DNA was isolated from blood samples of all 12 members of this family. The mutated PTCH gene was screened by polymerase chain reaction amplification and direct sequencing. Results A new mutation of 3 bp （GAT deletion） was found in all seven affected members of this family. This mutation caused one aspartate deletion in the fourth transmembrane domain of the PTCH protein located within the sterol sensing domain （SSD）. This deletion was not found in any unaffected members of this family nor in 200 control samples.
Conclusions Our findings suggest that one 3-bp deletion in PTCH gene was the cause of nevoid basal cell carcinoma in a Chinese family through affecting the conformation and function of PTCH protein.     

颗粒状角膜营养不良一家系的BIGH3基因突变研究

 【摘要】 目的 对一颗粒状角膜营养不良家系进行分子遗传学分析, 探讨BIGH3基因突变的类型。方法 收集一颗粒状角膜营养不良家系中2名患者和1名家系中正常成员的外周血5ml,提取白细胞DNA,利用合成的BIGH3基因第4、11和12外显子的特异性引物, 进行聚合酶链反应 (PCR)扩增, 并对PCR产物直接DNA测序分析。结果 该家系患者成员的BIGH3基因第4外显子存在CGC>CAC (R124H) 突变杂合子, 家系表现正常成员无此基因位点突变。结论 该颗粒状角膜营养不良家系存在BIGH3基因突变, 为R124H杂合突变类型,确诊为Avellino角膜营养不良。