1例神经纤维瘤病家系致病基因鉴定及产前诊断分析

目的 探讨Ⅰ型神经纤维瘤病家系进行基因检测与产前诊断的临床价值。方法 应用高通量测序对先证者行基因检测，进一步通过Sanger测序验证突变位点，然后检测其家系NF1基因突变位点，明确致病突变后通过绒毛活检术取胎儿样本进行产前基因诊断。结果 高通量测序结果提示先证者样本在NF1基因编码区发现两处杂合变异，分别是c.702G>A同义突变和c.3044T>G(p.Leu1015Arg)错义突变，其父亲，母亲，大姐，二姐，三姐及妻子并未检测出NF1错义突变位点。产前诊断结果表明胎儿样本在NF1基因未发现异常突变。结论 通过高通量测序联合Sanger测序技术可快速筛查出先证者致病突变，从而指导产前诊断，降低异常儿的出生。     

新疆3个HCM家系MYH7基因突变DHPLC检测和DNA测序结果分析

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突变情况.方法 用变性高效液相色谱DHPLC检测和DNA测序方法对3个HCM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.结果 3个家系其中1个家系发现MYH7基因14外显子中存在Thr441Met突变,该突变在中国人中是首次发现,此外外显子8也存在1个点突变.另外两个家系也发现有不同位点的突变.结论 运用变性高效液相色谱技术和DNA直接测序技术能实现对家族性肥厚型心肌病MYH7基因突变的筛查,有利于早期诊断、患病风险预测.     

β-肌球蛋白重链基因与肥厚型心肌病临床表型关系的研究

目的 研究肥厚型心肌病(hypertrophic cardiomyopathy,HCM)的主要致病基因β-肌球蛋白重链基因(beta-myosin heavy chin gene,MYH7)的突变位点,探寻基因型与表型的关系.方法 扩增3个HCM家系成员的MyH7基因第3、5、7～9、11～16、18～23外显子序列,进行直接测序分析,应用软件与标准序列比对,确定可能的突变位点.结果 发现其中1个家系MYH7基因第14外显子存在Thr441Met 突变,正常对照组相同位置未见异常.3个家系均发现多个同义突变位点.结论 在中国汉族人群中发现MYH2基因Thr441Met突变,该突变位于β-肌球蛋白重链头部肌动蛋白结合位点,可能是HCM的致病突变.HCM具有遗传异质性,多种因素可能参与其发生和发展过程.     

心脏肌球蛋白结合蛋白C基因G4295A突变与中国家族性肥厚型心肌病临床表型的关系

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100例肥厚型心肌病患者以及120例健康对照者中进行心脏型肌球蛋白结合蛋白C基因（MYBPC3）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2例HCM（ZHQ和JXW）患者中发现MYBPC3基因第6号外显子第4295位碱基由G转换为A,结果导致第258位的谷氨酸（Glu, E）转变为赖氨酸（Lys, K）,正常对照组相同位置未发现异常。对这2例先证者进行家系调查发现ZHQ和JXW家族受调查者中分别还有2名和1名成员携带该突变,但均未发病。结论 MYBPC3基因为我国家族性 HCM的致病基因之一,E258K突变所致肥厚型心肌病表型呈现外显率较低且临床症状相对较轻的特点。     

斑驳病1家系临床及致病基因检测研究

目的 研究中国汉族1斑驳病家系临床表现及其致病基因突变。方法 收集1斑驳病家系2代3个体的临床信息和外周血,提取样本外周血基因组DNA。对家系其中1个患者的基因组DNA进行全外显子组捕获并进行高通量测序,对候选变异位点在家系样本DNA中进行Sanger测序验证。结果 先证者自出生起额头出现一白斑,横跨发际线,白斑处头发为白发。左小腿少量白斑,右小腿多处白斑。全外显子组测序和Sanger测序验证发现IV2患者KIT c.2424T>G (p.Ile808Met)突变。此为一新突变位点,目前文献及数据库未见报道。结论 1个KIT基因新突变位点导致斑驳病家系。     

结节性硬化症TSC1/TSC2基因突变的高通量测序快速诊断

目的建立结节性硬化症TSC1/TSC2基因高通量测序技术以快速准确检测结节性硬化的TSC基因突变。方法对10例结节性硬化症患者及10例正常对照进行研究,利用长链PCR方法扩增TSC1及TSC2基因所有外显子区域,运用Ion PGMTM平台进行二代测序并运用常规测序验证。结果设计引物对TSC1及TSC2基因特异性扩增出7个长片段产物,产物长度介于13 kb~15 kb间;运用二代测序技术快速鉴定出10个致病突变,其中,7个突变位于TSC2基因,3个突变位于TSC1基因;所有突变经常规Sanger测序验证,结果一致。结论高通量二代测序技术可快速可靠诊断结节性硬化症TSC1、TSC2基因突变。     

后极性白内障家系致病基因的筛查及表型研究

目的对中国一个具有常染色体显性遗传特点的先天性后极性白内障家系进行疾病相关候选基因筛查,并研究其相关表型。方法抽取该家系患者及健康者外周静脉血并提取基因组DNA,通过靶向高通量测序技术筛查出先证者的致病突变,再通过Sanger测序进行家系验证以及家系内的共分离检验分析。结果高通量测序筛查发现先证者EPHA2基因存在可疑致病突变(c.2826-9G>A,IN 16,Het)。通过家系验证,确定该家系所有患者在EPHA2基因16号内含子区均有1个剪接突变c.2826-9G>A。结论此家系的致病基因为EPHA2,突变为c.2826-9G>A,该突变可造成晶状体的先天性异常,可确定为该后极性白内障家系的致病突变。     

应用下一代半导体靶向测序技术检测Marfan综合征致病突变

目的 应用Ion Torrent PGM半导体测序仪和Ion AmpliSeqTMInherited Disease Panel对3例马凡综合征(Marfan syndrome,MFS)进行致病基因突变检测,明确其致病突变,并评价下一代半导体靶向测序诊断复杂单基因遗传病的效果.方法 在知情同意的基础上采集3例MFS患者及1名正常志愿者外周血,提取基因组DNA,经多重PCR扩增富集目的基因片段.每个样本用特异性序列标签进行标记后,应用Ion One Touch系统进行模板制备、乳化PCR及磁珠颗粒富集;最后用318半导体测序芯片进行高通量测序.用Ion Torrent Suite 3.2软件进行序列比对及SNPs和Indels提取,再用dbSNP 137数据库过滤得到SNPs和indels,剩余的可疑突变经Sanger法测序验证.结果 用一张318芯片得到855.80Mb的总数据量,4个样本的平均测序深度均达到100×以上,对目的区域的覆盖度在98％以上.数据经软件分析及数据库过滤后,在3例MFS患者中分别得到3个FBN1基因可疑突变,并经Sanger法测序验证,一个为已报道FBN1基因错义突变(p.E1811K),另外两个为新发现的突变,包括一个无义突变(p.E2264X),1个插入突变(p.L871FfsX23).结论 在3例MFS患者中都成功检出FBN1基因致病突变,表明半导体靶向测序可对复杂单基因遗传病进行高效、准确的基因诊断.     

中国皖南地区家族性肥厚型心肌病MYH7基因筛查结果及临床特征

目的研究皖南地区汉族人群家族性肥厚型心肌病（HCM）的致病基因β肌球蛋白重链（MYH7）突变,并分析基因型与表型的关系。方法对4个HCM家系先证者的MYH7基因,经PCR扩增其外显子片段,用双脱氧末端终止法测序做突变初筛,对阳性结果患者进行家系调查,分析其临床表型。结果在MYH7基因18外显子中发现其中一家系中患者发现Arg663His突变,另一家系患者发现nt2013c缺失、nt2025C插入,此为一国内罕见移码突变。结论MYH7基因可能是皖南地区HCM较常见致病相关基因之一,其某些突变可在同一家系内遗传并致病,所致HCM临床症状较轻,症状出现较晚、进展较慢。同一突变携带者的临床表型存在异质性提示多因素参与了HCM的发生和发展。     

一个良性家族性新生儿惊厥家系的临床及基因变异分析CSCD

目的分析一个中国良性家族性新生儿惊厥(benign familial neonatal convulsions,BFNC)家系的临床特点,鉴定该家系的致病基因突变类型。方法收集2020年2月在宣城市中心医院新生儿科就诊的一个BFNC家系的临床资料和外周血样DNA,进行全外显子测序,筛选出的致病基因突变位点,采用Sanger测序法对每个家系成员的目标位点进行验证。结果该BFNC家系共9名成员,有4例受累者,其中男性3例、女性1例,起病年龄均在新生儿期,4~6月内惊厥发作停止,1例在1~2岁内复发1次。基因检测分析发现先证者KCNQ2基因第5外显子c.810G>A(p.W270X)杂合无义突变,该突变国内外文献均无报道。经Sanger测序验证,患儿哥哥、母亲及外公均携带该变异,该变异在该家庭中与疾病共分离。结论家系受累者均在新生儿期发病,预后良好,符合BFNC临床发病特点。KCNQ2基因无义突变C.810G>A(p.W270X)是该家系发病的遗传学基础,此发现拓宽了导致BFNC的KCNQ2基因突变谱。     

A DNA resequencing array for pathogenic mutation detection in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a heterogeneous autosomal dominant cardiac disorder with a prevalence of 1 in 500. Over 450 different pathogenic mutations in at least 16 genes have been identified so far. The large allelic and genetic heterogeneity of HCM requires high-throughput, rapid, and affordable mutation detection technologies to efficiently integrate molecular screening into clinical practice. We developed a custom DNA resequencing array that contains both strands of all coding exons (160), splice-site junctions, and 5'UTR regions of 12 genes that have been clearly implicated in HCM (MYH7, MYBPC3, TNNT2, TPM1, TNNI3, MYL3, MYL2, CSRP3, PLN, ACTC, TNNC1, and PRKAG2). We analyzed a first series of 38 unrelated patients with HCM (17 familial, 21 sporadic). A total of 953,306 bp across the 38 patients were sequenced with a mean nucleotide call rate of 96.92% (range: 93-99.9%). Pathogenic mutations (single nucleotide substitutions) in MYH7, MYBPC3, TNNI3, and MYL3 (six known and six novel) were identified in 60% (10/17) of familial HCM and 10% of sporadic cases (2/21). The high-throughput HCM resequencing array is the most rapid and cost-effective tool for molecular testing of HCM to date; it thus has considerable potential in diagnostic and predictive testing, and prognostic stratification.     

Whole-exome sequencing identifies rare compound heterozygous mutations in the MYBPC3 gene associated with severe familial hypertrophic cardiomyopathy

Most patients with hypertrophic cardiomyopathy have single-gene autosomal dominant mutations in loci that encode for sarcomeric proteins. The aim of this study was to determine whether pathogenic mutations were present by whole-exome sequencing (WES) in two families with hypertrophic cardiomyopathy (HCM) that presented during adolescence. Blood samples and clinical data were collected from individuals in two families with HCM. DNA was extracted. Mutations were identified using whole-exome sequencing (WES), and the genotypes of family members were identified using Sanger sequencing. Compound heterozygous mutations in the MYBPC3 gene (c.659A?>?G, p.Tyr220Cys; c.772G?>?A, p.Glu258Lys,NM_000256, Family 1), (c.873delG, p. Ile292PhefsTer8; c.3G?>?A, p.Met1?, NM_000256, Family 2) were identified by WES. Patient 1 carried the maternally inherited c.659A?>?G mutation and the paternally inherited c.772G?>?A mutation. Patient 2 carried the maternally inherited frameshift mutation c.873delG and the paternally inherited mutation c.3G?>?A. Two families with HCM presenting during adolescence (age of onset is about 11 years old) demonstrated compound heterozygous mutations in the MYBPC3 gene. These findings suggested an association of MYBPC3 mutations with the early onset of symptoms and worsened prognoses. Our study highlights the importance of genetic screening of all family members in cases of HCM.     

一例德朗热综合征患儿的致病基因变异分析

目的对1例疑诊德朗热综合征(Cornelia de Lange syndrome,CdLS)的患儿进行致病基因变异检测,明确其发病原因。方法应用高通量捕获测序对CdLS相关致病基因(NIPBL、SMC1A、SMC3、RAD21和HDAC8)进行测序,用Sanger测序验证测序结果以及致病基因的家系分析。结果患儿NIPBL基因存在c.6109-1G>A杂合剪接变异,Sanger测序验证结果表明患儿父母均未携带此变异,提示为新发变异,该变异未在HGMD及ExAC数据库收录。根据Human Splicing Finder预测剪接软件,预测该剪接变异将改变NIPBL基因剪接位点,为致病性变异。未发现SMC1A、SMC3、RAD21和HDAC8基因致病性变异。结论NIPBL基因c.6109-1G>A剪接变异可能是该例患儿的发病原因,新变异的检出丰富了NIPBL基因变异谱。     

Whole MYBPC3 NGS sequencing as a molecular strategy to improve the efficiency of molecular diagnosis of patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common heritable cardiomyopathy, historically believed to affect 1 of 500 people. MYBPC3 pathogenic variations are the most frequent cause of familial HCM and more than 90% of them introduce a premature termination codon. The current study aims to determine the prevalence of deep intronic MYBPC3 pathogenic variations that could lead to splice mutations. To improve molecular diagnosis, a next‐generation sequencing (NGS) workflow based on whole MYBPC3 sequencing of a cohort of 93 HCM patients, for whom no putatively causative point mutations were identified after NGS sequencing of a panel of 48 cardiomyopathy‐causing genes, was performed. Our approach led us to reconsider the molecular diagnosis of six patients of the cohort (6.5%). These HCM probands were carriers of either a new large MYBPC3 rearrangement or splice intronic variations (five cases). Four pathogenic intronic variations, including three novel ones, were detected. Among them, the prevalence of one of them (NM_000256.3:c.1927+ 600 C>T) was estimated at about 0.35% by the screening of 1,040 unrelated HCM individuals. This study suggests that deep MYBPC3 splice mutations account for a significant proportion of HCM cases (6.5% of this cohort). Consequently, NGS sequencing of MYBPC3 intronic sequences have to be performed systematically.     

Mutation spectrum in a large cohort of unrelated consecutive patients with hypertrophic cardiomyopathy

Defects in nine sarcomeric protein genes are known to cause hypertrophic cardiomyopathy (HCM). Mutation types and frequencies in large cohorts of consecutive and unrelated patients have not yet been determined. We, therefore, screened HCM patients for mutations in six sarcomeric genes: myosin-binding protein C3 (MYBPC3), MYH7, cardiac troponin T (TNNT2), alpha-tropomyosin (TPM1), cardiac troponin I (TNNI3), and cardiac troponin C (TNNC1). HCM was diagnosed in 108 consecutive patients by echocardiography (septum >15 mm, septal/posterior wall >1.3 mm), angiography, or based on a state after myectomy. Single-strand conformation polymorphism analysis was used for mutation screening, followed by DNA-sequencing. A total of 34 different mutations were identified in 108 patients: 18 mutations in MYBPC3 in 20 patients [intervening sequence (intron) 7 + 1G > A and Q1233X were found twice], 13 missense mutations in MYH7 in 14 patients (R807H was found twice), and one amino acid change in TPM1, TNNT2, and TNNI3, respectively. No disease-causing mutation was found in TNNC1. Cosegregation with the HCM phenotype could be demonstrated for 13 mutations (eight mutations in MYBPC3 and five mutations in MYH7). Twenty-eight of the 37 mutation carriers (76%) reported a positive family history with at least one affected first-grade relative; only eight mutations occurred sporadically (22%). MYBPC3 was the gene that most frequently caused HCM in our population. Systematic mutation screening in large samples of HCM patients leads to a genetic diagnosis in about 30% of unrelated index patients and in about 57% of patients with a positive family history.     

Systematic analysis of the regulatory and essential myosin light chain genes: genetic variants and mutations in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) can be caused by mutations in genes encoding for the ventricular myosin essential and regulatory light chains. In contrast to other HCM disease genes, only a few studies describing disease-associated mutations in the myosin light chain genes have been published. Therefore, we aimed to conduct a systematic screening for mutations in the ventricular myosin light chain genes in a group of clinically well-characterised HCM patients. Further, we assessed whether the detected mutations are associated with malignant or benign phenotype in the respective families. We analysed 186 unrelated individuals with HCM for the human ventricular myosin regulatory (MYL2) and essential light chain genes (MYL3) using polymerase chain reaction, single strand conformation polymorphism analysis and automated sequencing. We found eight single nucleotide polymorphisms in exonic and adjacent intronic regions of MYL2 and MYL3. Two MYL2 missense mutations were identified in two Caucasian families while no mutation was found in MYL3. The mutation Glu22Lys was associated with moderate septal hypertrophy, a late onset of clinical manifestation, and benign disease course and prognosis. The mutation Arg58Gln showed also moderate septal hypertrophy, but, in contrast, it was associated with an early onset of clinical manifestation and premature sudden cardiac death. In conclusion, myosin light chain mutations are a very rare cause of HCM responsible for about 1% of cases. Mutations in MYL2 could be associated with both benign and malignant HCM phenotype.     

Prevalence and spectrum of mutations in a cohort of 192 unrelated patients with hypertrophic cardiomyopathy

Hypertrophic Cardiomyopathy (HCM), a common and clinically heterogeneous disease characterized by unexplained ventricular myocardial hypertrophy and a high risk of sudden cardiac death, is mostly caused by mutations in sarcomeric genes but modifiers genes may also modulate the phenotypic expression of HCM mutations. The aim of the current study was to report the frequency of single and multiple gene mutations in a large French cohort of HCM patients and to evaluate the influence of polymorphisms previously suggested to be potential disease modifiers in this myocardial pathology. We report the molecular screening of 192 unrelated HCM patients using denaturing high-performance liquid chromatography/sequencing analysis of the MYBPC3, MYH7, TNNT2 and TNNI3 genes. Genotyping of 6 gene polymorphisms previously reported as putative HCM modifiers (5 RAAS polymorphisms and TNF-α -308 G/A) was also performed. Seventy-five mutations were identified in 92 index patients (48%); 32 were novel. MYBPC3 mutations (25%) represent the most prevalent cause of inherited HCM whereas MYH7 mutations (12%) rank second in the pathogenesis. The onset age was older in patients carrying MYBPC3 mutations than in those with MYH7 mutations. The MYBPC3 IVS20-2A>G splice mutation was identified in 7% of our HCM population. Multiple gene mutations were identified in 9 probands (5%), highlighting the importance of screening other HCM-causing genes even after a first mutation has been identified, particularly in young patients with a severe phenotype. No single or cumulative genetic modifier effect could be evidenced in this HCM cohort.     

Familial hypertrophic cardiomyopathy: genes, mutations and animal models. A review

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant disease, which may afflict as many as 1 in 500 subjects (0.2%), being probably the most common hereditary cardiovascular disease and the most common cause of sudden cardiac death (SCD). Hypertrophic cardiomyopathy is characterized by the presence of unexplained left ventricular hypertrophy (in absence of hypertension, valvular disease, etc), which is usually asymmetric and involves the ventricular septum. Molecular genetic studies have identified eleven genes that code proteins of the sarcomere that are associated with the HCM; the beta-myosin heavy chain gene (MYH7), alpha-myosin heavy chain (MYH6), cardiac troponin T (TNNT2); cardiac troponin C (TNNC1), alpha-tropomyosin (TPM1), myosin binding protein-C (MYBPC3), cardiac troponin (TNNI3), essential and regulatory light chain genes (MYL3 and MYL2, respectively), cardiac alpha-actin gene (ACTC) and titin (TTN). The objective of this paper is the revision of the current state of the knowledge on (1) the organization and mutations of the HCM causing genes and their proteins and (2) the animal models developed for the study of the genes, mutations and proteins in the hypertrophic cardiomyopathy.     

A cardiac myosin binding protein C mutation in the Maine Coon cat with familial hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is one of the most common causes of sudden cardiac death in young adults and is a familial disease in at least 60% of cases. Causative mutations have been identified in several sarcomeric genes, including the myosin binding protein C (MYBPC3) gene. Although numerous causative mutations have been identified, the pathogenetic process is still poorly understood. A large animal model of familial HCM in the cat has been identified and may be used for additional study. As the first spontaneous large animal model of this familial disease, feline familial HCM provides a valuable model for investigators to evaluate pathophysiologic processes and therapeutic (pharmacologic or genetic) manipulations. The MYBPC3 gene was chosen as a candidate gene in this model after identifying a reduction in the protein in myocardium from affected cats in comparison to control cats (P<0.001). DNA sequencing was performed and sequence alterations were evaluated for evidence that they changed the amino acid produced, that the amino acid was conserved and that the protein structure was altered. We identified a single base pair change (G to C) in the feline MYBPC3 gene in affected cats that computationally alters the protein conformation of this gene and results in sarcomeric disorganization. We have identified a causative mutation in the feline MYBPC3 gene that results in the development of familial HCM. This is the first report of a spontaneous mutation causing HCM in a non-human species. It should provide a valuable model for evaluating pathophysiologic processes and therapeutic manipulations.     

The role of sarcomere gene mutations in patients with idiopathic dilated cardiomyopathy

We investigated a Danish cohort of 31 unrelated patients with idiopathic dilated cardiomyopathy (IDC), to assess the role that mutations in sarcomere protein genes play in IDC. Patients were genetically screened by capillary electrophoresis single strand conformation polymorphism and subsequently by bidirectional DNA sequencing of conformers in the coding regions of MYH7, MYBPC3, TPM1, ACTC, MYL2, MYL3, TNNT2, CSRP3 and TNNI3. Eight probands carried disease-associated genetic variants (26%). In MYH7, three novel mutations were found; in MYBPC3, one novel variant and two known mutations were found; and in TNNT2, a known mutation was found. One proband was double heterozygous. We find evidence of phenotypic plasticity: three mutations described earlier as HCM causing were found in four cases of IDC, with no history of a hypertrophic phase. Furthermore, one pedigree presented with several cases of classic DCM as well as one case with left ventricular non-compaction. Disease-causing sarcomere gene mutations were found in about one-quarter of IDC patients, and seem to play an important role in the causation of the disease. The genetics is as complex as seen in HCM. Thus, our data suggest that a genetic work-up should include screening of the most prominent sarcomere genes even in the absence of a family history of the disease.