假肥大型肌营养不良基因突变检测方法的应用比较

目的比较假肥大型肌营养不良基因突变各种检测方法的优缺点,为不同条件下选择最佳的检测方案提供借鉴。方法分别应用18对引物多重PCR和5×4DNA微阵列对30例假肥大型肌营养不良患者进行dystrophin基因(缺失)检测分析,并结合文献中的方法进行应用比较。结果 30例假肥大型肌营养不良患者中有21例至少存在一个外显子片段缺失,占总例数的70%;9例未被检测到缺失,点30%。末检测到全部缺失的患者。PCR、DNA微阵列检测结果一致。结论对于假肥大型肌营养不良患者及携带者可选择MLPA检测缺失和重复突变,对于阴性者再利用PCR联合DHPLC结合测序检测点突变。经济方案是先选择18对引物定量PCR或DNA微阵列检测常见外显子缺失和重复突变,对于阴性者再用MLPA检测其它外显子缺失和重复突变。对于可疑胎儿产前诊断行MLPA或PCR-STR连锁分析。     

针吸型肌肉活检联合免疫荧光在假肥大型肌营养不良诊断中的应用

目的 探讨应用针吸型肌肉活检结合免疫荧光染色诊断假肥大型肌营养不良症的应用价值及意义。方法 应用针吸型活检术取533例假肥大型肌营养不良症患者(415例DMD, 118例BMD)的肌组织,采用HE染色观察肌细胞形态,免疫荧光染色技术检测抗肌营养不良蛋白, 以2 例正常人的肌细胞作为对照。结果 正常人肌细胞膜上抗肌萎缩蛋白染色阳性,可见沿肌细胞膜分布完整的荧光条带; DMD 患者肌膜染色阴性,肌细胞膜完全不显色; BM D患者染色弱阳性, 可见沿肌细胞膜分布的间断斑片状荧光带。结论 应用针吸型活检术联合免疫荧光染色可以有效的检测抗肌营养不良蛋白的表达, 有助于DMD 和BMD 的确诊及鉴别诊断。     

DMD基因新发错义突变致Becker型肌营养不良症一家系临床表型及基因突变分析

目的总结DMD基因新发错义突变导致的Becker型肌营养不良症一家系临床表型及基因突变特点。方法与结果采用第二代测序技术对1例25岁男性Becker型肌营养不良症患者进行基因检测,Sanger测序进一步验证患者之母和妹DMD基因c.4449T G(p.Asn1483Lys)位点,并结合患者及其家族成员的临床资料进行分析。结果显示,患者及其两位舅父具有相同的临床表型,双小腿肌肉呈假性肥大,双下肢近端肌萎缩和肌无力,血清肌酸激酶水平升高。患者基因检测DMD基因外显子34c.4449T G(p.Asn1483Lys)为错义突变,经检索为新发突变,其母和妹为携带者,结合患者两位舅父临床表现,确诊为Becker型肌营养不良症,该家系为Becker型肌营养不良症家系且存在该基因突变位点的共分离现象。结论 DMD基因外显子34 c.4449T G(p.Asn1483Lys)为新发错义突变,丰富了DMD基因突变谱,为该家系遗传咨询和产前诊断提供了有价值的信息。     

多重连接探针扩增和二代测序技术检测Duchenne型肌营养不良基因分析

目的探讨联合应用MLPA和二代基因测序技术对Duchenne型肌营养不良症分子遗传学诊断的作用。方法收集2012-01—2019-12在中山大学孙逸仙纪念医院儿童神经内分泌专科就诊经临床和肌肉活检明确诊断Duchenne型肌营养不良症患儿,联合应用MLPA和二代测序技术,分析其DMD基因单个外显子的缺失情况。结果纳入Duchenne型肌营养不良症患儿59例,均为男性,就诊年龄(4.72±2.42)岁。58例患儿确定了致病基因突变位点,基因诊断阳性率为98.30%。其中缺失突变28例(47.46%),以第45-55号外显子缺失频率最高;重复突变7例(11.86%),23例(38.98%)微小突变,其中包括无义突变8例(13.55%),移码突变6例(10.17%),错义突变6例(10.17%),微缺失3例(5.08%)。结论联合应用MLPA和二代测序技术是明确Duchenne型肌营养不良症致病基因突变位点最佳策略,能为Duchenne型肌营养不良症的精准诊治和家系成员的遗传咨询提供准确的依据。     

应用不同基因检测方法分析假肥大型肌营养不良基因的变异特点

目的通过对临床诊断为假肥大型肌营养不良症的患者进行基因变异检测,探讨DMD基因变异的特点。方法收集7例无亲缘关系的DMD患者及3例BMD患者的血液,应用多重连接依赖式探针扩增技术对患者DMD基因进行外显子缺失/重复突变分析;对于MLPA检测为单个外显子缺失者,进行PCR扩增及Sanger测序以排除假阳性;对MLPA检测为阴性者,应用外显组测序技术进行测序,并特别关注79个外显子及其剪切位点的变异,通过Sanger测序验证发现的突变,并利用ACMG评级及生物学危害性预测判定基因变异的危害性。结果MLPA技术检测出8例患者存在DMD基因外显子缺失,且第44～55外显子缺失最常被观察到;外显组测序和Sanger测序检测出2例患者存在DMD基因新发点突变。其中一个点突变为错义突变(c. 116(exon6) G> T),可能致病,另一个是无义突变,位于非编码区突变c. 6832-26(IVS49) G> A,致病性不确结论本研究结果表明DMD基因存在多种基因改变形式;联合使用MLPA、外显组测序和Sanger测序方法是检测DMD基因变异的合理选择。     

DMD基因点突变致Becker型肌营养不良症临床研究

研究背景DMD基因点突变,主要是无义突变,可以引起基因编码提前终止,使产生的目的蛋白不稳定而降解,导致临床症状较重的Duchenne型肌营养不良症,而在实际工作中可见临床表型为症状较轻的Becker型肌营养不良症的DMD点突变患者。本研究旨在探讨DMD基因点突变导致Becker型肌营养不良症的发病机制,以加深对Becker型肌营养不良症基因突变类型的认识。方法共11例临床和肌肉活检明确诊断、多重连接依赖性探针扩增(MLPA)显示DMD基因外显子非缺失或重复突变的Becker型肌营养不良症患者,高通量第2代DNA测序法检测DMD基因外显子突变类型。结果11例Becker型肌营养不良症患者携带10种突变类型,无突变热点;6例携带无义突变[c.5002GT,p.(Glu1668X);c.1615CT,p.(Arg539X);c.7105GT,p.(Glu2369X);c.5287CT,p.(Arg1763X);c.9284TG,p.(Leu3095X)];1例携带错义突变[c.5234GA,p.(Arg1745His)];2例携带框移突变(c.10231dup T,c.10491del C);2例携带剪切位点突变(c.4518+3AT,c.649+2TC)。结论 DMD基因点突变可以引起临床症状较轻的Becker型肌营养不良症,当MLPA技术显示DMD基因为非缺失和重复突变时,切勿漏诊Becker型肌营养不良症,研究其发生机制对基因治疗Duchenne型肌营养不良症有重要借鉴意义。     

肌营养不良症致病基因编码产物检测的初步研究

目的对导致肌营养不良症的基因编码产物进行检测，从分子水平为临床诊断和分型提供依据。方法应用蛋白质印迹技术对临床诊断为肌营养不良症的患者进行抗肌营养不良蛋白、αｓａｒｃｏｇｌｙｃａｎ和γｓａｒｃｏｇｌｙｃａｎ的研究。结果首次在中国人群中检测出由于α和γｓａｒｃｏｇｌｙｃａｎ缺陷而致的常染色体连锁遗传性肢带型肌营养不良症２例，检测出由于抗肌营养不良蛋白缺陷而致的迪谢内肌营养不良症２例。结论肌营养不良症在临床症状、遗传模式等方面具有极不均一的特点。直接检测致病基因的编码产物不仅为临床诊断和分类提供了依据，也为进一步研究致病基因，阐明该病的病理机制奠定了基础     

假肥大型肌营养不良症基因治疗的成就和展望

假肥大型肌营养不良症基因治疗的成就和展望刘焯霖盛文利假肥大型肌营养不良症（ＤＭＤ）是神经肌肉系统最常见的Ｘ－连锁隐性遗传病。患者绝大多数为男性，通常在儿童期发病。临床主要表现为骨骼肌的进行性无力、萎缩，小腿腓肠肌的假性肥大等。与Ｄｕｃｈｅｎｎｅ型的临...     

抗肌萎缩蛋白相关蛋白复合体与Duchenne型肌营养不良症

Duchenne型肌营养不良症(Duchenne muscular dystrophy,DMD)与Becker型肌营养不良症(Becker muscular dys-trophy,BMD)统称为假肥大型肌营养不良症。DMD是一种X连锁隐性遗传的肌肉变性疾病,是肌营养不良症中最常见且     

进行性肌营养不良症71例临床分析

目的:探讨进行性肌营养不良症的临床特点及辅助诊断价值。方法 分析71例进行性肌营养不良症的临床资料及相关检查。结果 假肥大型占本病的44％为本病的最常见型,约45％有明确遗传史。30％DMD伴有智能减退。DMD及肢带型常伴有心肌损害。血清酶增高(CPK、LDH)以假肥大型明显,肢带型次之。结论 临床特点、血清生化检测、肌电图及肌活检是重要的辅助检查指标。     

MLPA analysis/complete sequencing of the DMD gene in a group of Bulgarian Duchenne/Becker muscular dystrophy patients

Duchenne/Becker muscular dystrophy (DMD/BMD), the most common X-linked muscular dystrophy is caused by mutations in the enormously large DMD gene, encoding the protein called dystrophin. This gene was screened in a group of 27 unrelated Bulgarian DMD/BMD patients by MLPA analysis/complete sequencing. We managed to clarify the disease-causing mutation in 96.3% of the analyzed families. The MLPA analysis revealed 17 deletions (including a deletion of the very last exon 79), 6 duplications and 1 point mutation. Two additional point mutations (one of them novel) were detected after complete sequencing of the DMD gene. Altogether, 25 carriers and 11 noncarriers were detected in our families. The MLPA test proved to be a powerful tool in detecting deletions/duplications and in some cases point mutations/polymorphisms along the DMD gene. Using this approach in combination with a direct gene sequencing a number of Bulgarian DMD/BMD patients are genetically clarified and prepared for gene therapy in future.     

应用多重连接依赖性探针扩增定量技术检测假肥大型肌营养不良重复突变及携带状态

目的 应用多重连接依赖性探针扩增(MLPA)技术对假肥大型肌营养不良(DMD及BMD)患者及其家系成员进行dystrophin基因分析,探讨MLPA定量技术在本病重复突变及携带者检测中的优势.方法 以355例DMD及BMD患者、46名缺失型患者之母和8名重复型患者之母为研究对象,应用MLPA技术对dystrophin基因全长外显子进行分析,对于单一外显子缺失的样本采用PCR及测序进行验证.结果 经MLPA分析,全部355例患者中190例为dystrophin基因缺失型患者,在其余非缺失型患者中检测出34例重复型突变.此外,在46名缺失型患者的母亲中发现了28名携带者,在8名重复型患者的母亲中发现了6名携带者,两组患者母亲携带者频率差异无统计学意义.经过测序验证,在1例单一外显子缺失的患者中发现17号外显子存在AGGGAACAGATCCTGGTAAAGCA小片段缺失.结论 与传统的定量方法相比,MLPA定量技术可对DMD及BMD患者全长外显子区域同时进行缺失、重复分析,并能对患者家系成员的携带状态进行判定.此外,MLPA检测结果受模板DNA的浓度及纯度影响较小.     

Dystrophin gene analysis in Hungarian Duchenne/Becker muscular dystrophy families – Detection of carrier status in symptomatic and asymptomatic female relatives

A comprehensive study of the Hungarian Duchenne/Becker muscular dystrophy (DMD/BMD) families is presented. Deletions in the hot spots regions were identified by multiplex PCR, whereas rare mutations were detected by Southern blot and multiplex ligation-dependent probe amplification (MLPA) techniques. DMD/BMD disease was confirmed and exact deletion borders were determined in 19 out of 135 affected males using multiplex PCR. Additional exons involved as well as rare exon deletions were identified by MLPA in 71 male patients, whereas duplications were observed in seven patients. In two DMD patients, the entire dystrophin gene and adjacent genes were deleted. Out of the 95 female relatives, 41 proved to be carriers, including three manifesting carrier females. Using MLPA method, a large portion of the Hungarian DMD/BMD patients and their female relatives were exactly genotyped. For the first time, the incidence and prevalence of asymptomatic and symptomatic female carriers in Hungary was estimated.     

Duchenne and Becker muscular dystrophy: a molecular and immunohistochemical approach

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are caused by mutations in the dystrophin gene. We studied 106 patients with a diagnosis of probable DMD/BMD by analyzing 20 exons of the dystrophin gene in their blood and, in some of the cases, by immunohistochemical assays for dystrophin in muscle biopsies. In 71.7% of the patients, deletions were found in at least one of the exons; 68% of these deletions were in the hot-spot 3' region. Deletions were found in 81.5% of the DMD cases and in all the BMD cases. The cases without deletions, which included the only woman in the study with DMD, had dystrophin deficiency. The symptomatic female carriers had no deletions but had abnormal dystrophin distribution in the sarcolemma (discontinuous immunostains). The following diagnoses were made for the remaining cases without deletions with the aid of a muscle biopsy: spinal muscular atrophy, congenital myopathy; sarcoglycan deficiency and unclassified limb-girdle muscular dystrophy. Dystrophin analysis by immunohistochemistry continues to be the most specific method for diagnosis of DMD/BMD and should be used when no exon deletions are found in the dystrophin gene in the blood.     

Rapid and cost effective detection of small mutations in the DMD gene by high resolution melting curve analysis

Duchenne/Becker muscular dystrophy (DMD/BMD) is caused by large deletions or duplications in two-thirds of the cases. The remaining one-third DMD patients have small mutations in the DMD gene. Screening for such small mutations is a daunting and costly task. High resolution melting curve analysis (HR-MCA) followed by sequencing for amplicons with altered melting profiles can be used to scan DNA for small alterations. We first validated the technique as screening procedure for the DMD gene and then screened a group of unrelated 22 DMD/BMD patients and 11 females. We managed to identify all previously found mutations by means of HR-MCA, which provided its validation. Furthermore, 17 different pathogenic mutations were found in the screening group, of which 10 were novel. Our results provide validation of HR-MCA as a powerful and inexpensive pre-sequencing scanning method. This technology is now ready for routine diagnostic use on DMD/BMD patients and female carriers.     

MLPA based detection of mutations in the dystrophin gene of 180 Polish families with Duchenne/Becker muscular dystrophy

Duchenne/Becker muscular dystrophy (DMD/BMD) is a recessive, X-linked disorder caused by a mutation in the dystrophin gene. Deletions account for approximately 60–65% of mutations, duplications for 5–10%. The remaining cases are mainly point mutations. According to Monaco theory clinical form of the disease depends on maintaining or disrupting the reading frame. The purpose of the study was to determine frequency and location of deletions and duplications in the dystrophin gene, to determine the compliance between maintaining/disrupting the reading frame and clinical form of the disease and to check the effectiveness of MLPA (multiplex ligation-dependent probe amplification) in the detection of these mutations in hemizygous patients and heterozygous female carriers. The material is composed of combined results of molecular diagnosis carried out in years 2009–2012 in 180 unrelated patients referred with the diagnosis of DMD/BMD tested by use of MLPA. We identified 110 deletions, 22 duplication (in one patient two different duplications were detected) and 2 point mutations. Deletions involved mainly exons 45–54 and 3–21, whereas most duplications involved exons 3–18. The compliance with Monaco theory was 95% for deletions and 76% for duplications. Most of mutations in the dystrophin gene were localized in the hot spots – different for deletions and duplications. MLPA enabled their quick identification, exact localization and determination whether or not they maintained or disrupted the reading frame. MLPA was also effective in detection of deletions and duplications in female carriers.     

Evolution of Molecular Diagnosis of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is the commonest of the muscular dystrophies. The DMD gene (DMD) is the biggest human gene and the most common molecular defect in the DMD gene, accounting for approximately 65 % of cases of DMD, is the deletion of one or more exons. The most basic method still in regular use involves multiplex PCR of the exons, known to be most commonly deleted. The multiplex is relatively simple. Quantitative analysis of all exons of the gene and multiplex ligation-dependent probe amplification have brought about an improvement in mutation detection rate, as they will detect all exon scale deletions as well as duplications, widely used to detect exonic and intronic mutations. As a sensitive and discriminative tool, MLPA can be used for prenatal testing. A more recent development in quantitative analysis is the use of oligonucleotide-based array comparative genomic hybridization.     

Central nervous system involvements in Duchenne/Becker muscular dystrophy]

Duchenne/Becker muscular dystrophy (DMD/BMD) are the most common inherited muscular diseases caused by mutations in the dystrophin gene. The identification of novel dystrophins in the brain has recently implicated its absence or malfunction etiologically in mental retardation (MR). We therefore examined the relationship between molecular abnormalities and clinical phenotypes. Deletions of the dystrophin gene were analyzed in a total of 137 DMD/BMD patients (DMD 94, BMD 43) to determine central nervous system (CNS) symptoms. The mental capacity was assessed and patients with IQs below 70 were defined as mentally retarded. Thirty-nine percent of DMD boys and 12% of BMD patients were classified as mentally retarded. Eight DMD and 2 BMD patients were diagnosed as having autism. Forty-four percent of DMD and 79% of BMD patients had deletions in the dystrophin gene. All the DMD/BMD patients with deletions upstream of the 5' end of the gene were mentally normal. All of DMD/BMD patients with MR and/or autism had deletions containing the 3' end, although some patients with similar deletions were mentally normal. Our data suggest that Dp140, Dp71 and/or Dp116, the C-terminal translational products of dystrophin, may be related to MR and/or autism in DMD/BMD. However, there was an exception in our series. Three of eight sibling pairs in our cases had different phenotypes, although they had the same mutations in the dystrophin gene. Thus the CNS phenotypes were not determined by the mutations of dystrophin gene alone, and the interaction of dystrophin with other nuclear genes may play important roles.     

MLPA analysis for the detection of deletions, duplications and complex rearrangements in the dystrophin gene: potential and pitfalls

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are common X-chromosomal recessive disorders caused by mutations in the dystrophin gene. Using the novel multiplex ligation-dependent probe amplification (MLPA) method we performed retrospective and prospective analyses in a total of 193 individuals. Deletions or duplications were identified in 14 out of 90 families previously tested negative by multiplex PCR or FISH analysis. Partially incorrect results were subsequently identified in two families: the loss of exon 38 signal in one case was due to a p.Q1802X nonsense mutation, whilst in another patient an apparent deletion of exon 37 (coinciding with a duplication of exons 46–53) was caused by a p.R1735C polymorphism. In one case we found a complex rearrangement involving a duplication of two regions: dupEX45–48 and dupEX54–55. We conclude that MLPA is a highly sensitive and rapid alternative to multiplex PCR. It can be used on blood samples, chorionic villi and paraffin-embedded tissue. The ease of detection of duplications and the application for female carrier analysis are clearly the main advantages of the method. However, apparent single exon deletions detected by MLPA should be checked by an independent method. Complex rearrangements such as double mutations on the same allele are rare.