Carrier detection by microsatellite analysis of Duchenne/Becker muscular dystrophy in Hungarian families

Duchenne and Becker muscular dystrophies are among the most severe and frequent inherited disorders. Being still incurable, medical treatment is concentrated on the carrier diagnosis of the members of the affected families. Here we report the results of the studies of 151 members of 41 Hungarian families, obtained with multiplex PCR amplification of 18 exons as well as the muscle specific promoter region, and haplotype analysis of two polymorphic (CA)_n repeat microsatellite loci in introns 45 and 49 of the dystrophin gene. The analysis of 15 deletion-type families revealed a frequency of new mutations not differing significantly from that in the other regions of Europe. We also compared the allele distributions of the two microsatellites in randomly selected normal individuals and affected family members. The allele distribution of STRP45 shows interesting differences between the two populations.     

应用多个微卫星DNA位点进行Duchenne/ Becker肌营养不良症携带者的检测

目的　筛查和确定 Duchenne/ Becker肌营养不良症 ( Duchenne/ Becker muscular dystrophy,DMD/ BMD)家系的女性成员中的致病基因携带者与正常者 ,为进一步行产前诊断或植入前遗传学诊断提供信息。方法　用 PCR方法对 dystrophin基因第 4 4、4 5、4 9和 5 0内含子以及 5′DMD 的短串联重复序列( short tandem repeats,STR)扩增 ,然后进行基因扫描、软件分析 ,对 4个 DMD/ BMD家系中 2 7个成员的这 5个微卫星 DNA位点的多态性进行连锁分析。结果　在 4个家系 17名女性成员中 (有 1例女性 DMD患者 ) ,系谱和 STR多态性分析结果均符合的 DMD基因肯定携带者有 6名 ;单纯根据 STR多态性连锁分析结果确诊为 DMD基因携带者的女性成员有 5名 ,确诊为正常女性成员有 5名。在这 5个 STR位点中 ,最具多态性的位点是 STR- 4 9,多态性最少的位点是 STR- 5 0。结论　短串联重复序列多态性结合基因扫描能快速、准确、客观地检出 Duchenne/ Becker型肌营养不良症的女性携带者     

假肥大型肌营养不良症家系的基因检测与产前诊断

目的 分析假肥大型肌营养不良症(Duchenne and Becker muscular dystrophy,DMD/BMD)家系的致病突变,对胎儿进行产前诊断,并确定家系中的女性成员是否为突变携带者.方法 收集43个DMD/BMD家系,用多重PCR方法分析DMD基因缺失热点区的18个外显子;用多重连接依赖性探针扩增(multiplex ligation-dependent probe amplification,MLPA)方法对43例患者及32个家系中的36位女性进行DMD基因全部79个外显子的定量检测,为其中27个家系提供产前诊断.结果 用多重PCR共检测到26例缺失突变.采用MLPA方法,除多重PCR检测到的突变外,还检测到3例缺失和6例重复突变,突变范围明确.用MLPA检测的36例女性中,32例为患儿母亲,共发现16例突变携带者,另有2名女性亲属也被确诊为携带者.10名女性排除了携带者的可能性,8例不能确定.经产前诊断,18例男性胎儿中3例为患者,9例女性胎儿中1例为携带者.结论 MLPA方法可全面检测DMD基因缺失及重复突变,同时明确女性携带者,从而为产前诊断提供准确信息.     

DNA analysis of Duchenne and Becker muscular dystrophy using pERT87 genomic probes and dystrophin cDNA probes

DNA analysis was performed on 19 unrelated Duchenne muscular dystrophy (DMD) families and one Becker muscular dystrophy (BMD) family in Japan to determine their carrier status. The intragenic genomic probe pERT87 with its subclones 87-1, 87-8, and 87-15 were used together with five cDNA probes from the 5 end of the dystrophin gene. The tests with both a high polymorphism information content (P.I.C.) and a high observed P.I.C. were most effective,i.e., pERT87-1/XmnI, pERT87-15/XmnI, pERT87-8/TaqI, and pERT87-8/BstXI. These test combinations were useful in the Japanese population but pERT87-15/TaqI was not, although it was effective in Caucasians. Two additional test combinations of pERT87-1/MspI and pERT87-15/BamHI, were highly useful in detecting restriction fragment length polymorphisms (RFLPs) when other tests were not informative. Carrier status could be determined in 18 out of 20 clients who were at risk for DMD/BMD carrier status from 20 families, similar to the rate of detection in Caucasians. The total detection rate of deletions was 74% with the five cDNA probes. Deletions were concentrated on two hot spots where 92% of all deletions were detected by only two probes, 1-2a and 8. Deletions were detected in two males with DMD who had none of the eight RFLPs tested. Our results emphasize the usefulness of DNA analysis with pERT87 genomic probes and cDNA probes. In addition, an optimum strategy for carrier detection in Japanese DMD/BMD families was proposed.     

Duchenne型肌营养不良症家系的多重PCR和STR—PCR基因诊断

目的该研究率先开展温州地区Duchenne型肌营养不良症（DMD）家系的缺失基因诊断特别是STR单体型连锁基因诊断,为基于DMD症状前、携带者基因诊断结果的遗传咨询和生育指导提供依据。方法针对4例DMD先证者,采用多重PCR检测常见18个外显子缺失,进行直接基因诊断。针对未能发现常见外显子缺失的DMD先证者及其有关家系成员,采用短串联重复序列（STR）PCR检测5个位点（3’CA、44CA、45CA、49CA和50CA）STR多态性,进行间接单体型连锁基因诊断。结果家系二的先证者缺失外显子3、4和6。其余3个家系的先证者的异常x染色体均肯定来源于其母亲。家系一先证者外婆肯定是携带者。家系三先证者年幼（4周岁）弟弟肯定为正常人,将来年龄大了也不会发病,先证者外婆肯定是携带者。家系四先证者刚出生的妹妹肯定是遗传携带者,将来其生育儿子有遗传患病风险。结论该研究的DMD家系的缺失和STR单体型连锁基因诊断,特别是对症状前男孩的诊断、对无患病后代的女性携带者的检出,具有非常重要的实际意义,可以为遗传咨询和生育指导提供可靠依据。     

Carrier detection in Duchenne muscular dystrophy.

We measured endogenous phosphorylation of peak II (apparent molecular weight of 220,000 daltons) of the erythrocyte membrane in 21 mothers of patients with Duchenne muscular dystrophy. The mean values of mothers with affected sons were significantly increased over those of matched controls (77.0 and 55.8 pmoles per milligram of 15-minute incubation; P less than 0.01). Detailed testing of mothers of affected sons revealed proximal muscle weakness. Seven mothers of isolated patients who had normal levels of creatine phosphokinase and no daughters with elevated levels were identified as carriers, because their mean value of peak II phosphorylation was increased (75.9 pmoles per milligram per 15 minutes) and equivalent to the level demonstrated in the 14 acknowledged carriers. Our results suggest that cases of Duchenne muscular dystrophy previously considered to be new mutations are much less common than estimated.     

Carrier detection in Duchenne muscular dystrophy.

Serum creatine kinase, myoglobin, and percentage lymphocyte capping was determined in ten patients with Duchenne muscular dystrophy, 12 carriers (nine definite and three probable), 16 other female relatives, and eight normal controls. There was no detectable difference in lymphocyte capping ability between any of these clinical groups. Significant myoglobinaemia was present in all the affected males, but the difference in levels between carriers and controls suggested that this test has no advantage over creatine kinase estimations in carrier detection.     

应用DNA微阵列技术检测缺失型DMD/BMD患者的研究

目的研究Duchenne型肌营养不良（DMD）/Becker型肌营养不良（BMD）患者基因缺失检测的可行技术。方法应用分子克隆的方法扩增DMD基因18个常见易缺失外显予片段，以此作为探针制备出简易DNA微阵列，对30例DMD/BMD患者和5例健康对照的基因进行检测分析。部分结果与PCR方法比较结果一致性。结果应用简易DNA微阵列检测出21例DMD/BMD患者具有不同程度的外显予缺失，10例经PCR检测得到了完全验证。结论DNA微阵列技术检测缺失型DMD/BMD患者简便、准确、灵敏，具有临床应用价值。     

多重聚合酶链反应检测DMD／BMD患者的基因缺失

目的了解Duchenne型肌营养不良（DMD）／Becker型肌营养不良（BMD）患者基因缺失的分布规律,并探索检测技术。方法应用28对引物多重聚合酶链反应（mPCR）分4组对20例DMD／BMD患者进行Dysophin基因缺失检测分析。结果12例（60％）存在外显子缺失,8例（40％）未检测到缺失;8例缺失片段集中于44—52号外显子,4例集中于5’端外显子。结论基因缺失为主要突变类型,缺失片段主要分布于44—52、2～20号外显子两个缺失热区。     

假肥大型肌营养不良症基因诊断及遗传分析

目的对假肥大型肌营养不良症（DMD／BMD）患者进行基因诊断并对家系进行遗传分析,以提高对DMD／BMD的基因诊断水平及有效的遗传咨询。方法对40例DMD／BMD患者应用18对引物多重PCR技术进行Dystrophin基因缺失诊断,收集完整家系资料进行遗传分析以判断致病基因携带者及评估风险。结果40例DMD／BMD患者基因诊断有27例至少存在一个外显子片段缺失（67．5％）,13例未检测到缺失（32．5％）。通过对家系的遗传分析判断出致病基因携带者。结论多重PCR作为一种简便快速的诊断方法可对DMD／BMD患者进行基因诊断;对风险家系进行遗传分析、判断致病基因携带者以进行有效的遗传咨询,进而控制遗传病。     

Carrier detection in Duchenne muscular dystrophy using computed tomography

In Duchenne dystrophy computed tomography of muscles shows total or partial replacement of normal muscle by low density tissue, presumably representing fat. It was hypothesised that female carriers would have increased fat deposition, and hence lower density readings in certain muscle groups when compared with controls. Three C.T. scans, two through the thigh and one through the calf, were obtained on 9 obligate carriers, 12 "possible" carriers, and 10 controls. A total of 15 density readings in different muscle groups were obtained for each subject. The results, analysing the mean densities in Hounsfield units, show that the obligate carriers have statistically significant lower density readings than controls. The 9 obligate carriers and 10 controls were correctly allocated using discriminant function analysis of muscle density readings. An attempt to assign the "possible" carriers was made. The use of C.T. scanning in addition to creatine kinase (C. K.) estimations will significantly improve accuracy of genetic counselling and has the advantage of being non-invasive.     

Electromyographic pattern in Duchenne and Becker muscular dystrophy. Part II. Electromyographic pattern in Becker muscular dystrophy in comparison with Duchenne muscular dystrophy

BACKGROUND: The aim of this study was to compare the electromyographic pattern in Becker muscular dystrophy (BMD) with that found in Duchenne muscular dystrophy (DMD). MATERIAL AND METHOD: Fourteen men with BMD and 51 boys with DMD were investigated. Proximal muscles were examined: m. biceps brachii (BB) and m. rectus femoris (RF). They were divided according to the clinical criteria in two groups: of those with slight changes (group AB) and of those with severe abnormalities (CD). As in the Part I of the paper our own method of Functional-QEMG was applied in the CNEMG examination. RESULTS AND CONCLUSIONS: Spontaneous activity (fibrillations, complex repetitive discharges) was equally frequent in BMD and DMD. Linked potentials were rather frequent in either group. Myopathic features such as MUAPs low amplitude and area, polyphasic shape were seen in either condition, but more marked in DMD than in BMD. Evaluation of IP recordings revealed that IP amplitude (amplitude size) is low in DMD already at the early stage of lesion but normal or only slightly diminished in BMD. It might perhaps suggest different degrees of lesion in type II MUs between the compared types of muscular dystrophy.     

Carrier detection of Duchenne/Becker muscular dystrophy by analysis of STRs loci linked to the gene of dystrophin in Venezuelan families

The Duchenne/Becker Muscular Dystrophy (DMD/BMD) is an X linked recessive lethal disease. The female carrier will transmit the disease gene to half of her sons and half of her daughters; half of the daughters will be carriers, while half will be normal. Half of the sons will be normal and, on average, half will have the disease. It is of particular relevance to be able to detect carrier status among female relatives of the patients for genetic counseling and prenatal diagnosis. The method of Short Tandem Repeat (STR) sequence polymorphism analysis can determine haplotype at normal status or at risk status and, to establish genetic linkage between the mutated gene and the segregated haplotype. We have analyzed 105 members from 15 unrelated Venezuelan families with one or more siblings affected with DMD/DMB and 7 unrelated males. Of the 105, 37 were male (26 affected and 11 normal) and 68 were female. STR sequences (STR44, STR45, STR49, STR50, STR3'DYS) of the gene of the Dystrophin were amplified by polymerase chain reaction (PCR) to analyze allelic polymorphism in the families. Five of the 15 families (33%) had a deletion of one or several of the exons. Of the 68 females, 27 (39.7%) were carriers, 27 (39.7%) were non-carriers and in 14 cases (20.58%) it was not possible to reach a definitive diagnosis. The definitive diagnosis could be established in 79% of the females. This analysis also shows that the mutation occurred on the grandpaternal X chromosome in one family. Hemizygocity was detected and carrier status ascertained in the mother of other patient and in one family we were able to do prenatal diagnosis. The germinal mosaicism could not be excluded in 3 patients.     

DGGE-based whole-gene mutation scanning of the dystrophin gene in Duchenne and Becker muscular dystrophy patients

Duchenne and Becker muscular dystrophy (DMD and BMD) are caused by mutations in the dystrophin gene. Large rearrangements in the gene are found in about two-thirds of DMD patients, with approximately 60% carrying deletions and 5-10% carrying duplications. Most of the remaining 30-35% of patients are expected to have small nucleotide substitutions, insertions, or deletions. To detect these subtle changes within the coding and splice site determining sequences of the dystrophin gene, we established a semiautomated denaturing gradient gel electrophoresis (DGGE) mutation scanning system. The DGGE scan covers the dystrophin gene with 95 amplicons, PCRed either individually or in a multiplex setup. PCR and pooling were performed semiautomatically, using a pipetting robot and 384-well plates, enabling concurrent amplification of DNA of four patients in one run. Amplification of individual fragments was performed using one PCR program. The products were pooled just before gel loading; DGGE requires only a single gel condition. Validation was performed using DNA samples harboring 39 known DMD variants, all of which could be readily detected. DGGE mutation scanning was applied to analyze 135 DMD/BMD patients and potential DMD carriers without large deletions or duplications. In DNA from 25 out of 44 DMD patients (57%) and from 5 out of 39 BMD patients (13%), we identified clear pathogenic changes. All mutations were different, with the exception of one DMD mutation, which occurred twice. In DNA from 10 out of 44 potential DMD carriers, including four obligate carriers, we detected causative changes, including one pathogenic change in every obligate carrier. In addition to these pathogenic changes, we detected 15 unique unclassified variants, i.e., changes for which a pathogenic nature is uncertain.     

The value of deletion analysis for carrier detection in Duchenne muscular dystrophy (DMD)

We performed genetic analysis for carrier detection for several at-risk females in a four-generation Duchenne muscular dystrophy (DMD) pedigree using deletion analysis. We demonstrated that dosage analysis is a suitable alternative method to determine the carrier status of female relatives of DMD patients shown to have a deletion within the DMD gene. Subsequently, we diagnosed an affected male fetus for an at-risk female shown to be a DMD carrier by deletion analysis. The usefulness of deletion and linkage analysis are compared. In this family, linkage analysis was complicated by the unavailability of key family members, two recombination events and by previously undisclosed nonpaternity. We found that dosage analysis was more efficient than linkage for carrier evaluation in this family.     

Analysis of Scottish Duchenne and Becker muscular dystrophy families with dystrophin cDNA probes.

One hundred and thirty-two Scottish families, representing the majority of currently known cases in this country with at least one living subject affected by DMD (110) or BMD (22), were studied with a series of cDNA probes excluding the 3' region of the gene (probes 10-14). Using mainly HindIII digested DNA from affected males, 89 patients showed deletions which ranged from 1 to 32 HindIII fragments in size. Two patients were also detected with exon duplications. Abnormalities were found to be particularly concentrated in the area of probe cDNA 8, with 56 patients being deleted for at least one of the fragments detected by this probe. A second smaller concentration of deletions was found with probe 1-2a which showed 16 deletions and two duplications. The endpoints of cDNA deletions or duplications were determined with a maximum variability of one HindIII fragment in 83 patients, while the remaining eight patients had a single deletion endpoint defined. The deletions found in two of our patients appear to conflict with the previously stated exon order at the 5' end of the gene. Although no specific deletion patterns were apparent for DMD, the deletions found in 13 of the BMD patients all included the most proximal (10 kb) fragment detected by probe 8.     

High frequency of new mutations in North Indian Duchenne/Becker muscular dystrophy patients

Accurate carrier determination is an important aspect in providing prenatal diagnosis and genetic counselling to families with Duchenne/Becker muscular dystrophy patients. Using quantitative polymerase chain reaction, we have analyzed the carrier status of 31 mothers (8 familial and 23 sporadic) who have an affected son with known deletion in the dystrophin gene. Only four out of 23 mothers of sporadic cases turned out to be heterozygous for the deleted exons. The lower number of carrier mothers in sporadic cases suggests a higher frequency of new mutations in North Indian DMD/BMD patients.     

Duchenne/becker muscular dystrophy carrier detection using quantitative PCR and fluorescence-based strategies

Dystrophin gene deletions account for up to 68% of all Duchenne (DMD) and Becker (BMD) muscular dystrophy mutations. In affected males, these deletions can be detected easily using multiplex PCR tests which monitor for exon presence. In addition, quantitative dosage screening can discriminate female carriers. We previously analyzed multiplex PCR products by gel electrophoresis and quantitation of fluorescently labeled primers with the Gene Scanner? in order to test carrier status. These multiplex PCR protocols detect DMD gene deletions adequately, but require up to 18 pairs of fluorochrome-labeled primers. We previously described two alternative fluorescent labeling strategies, each with approximately 1,000-fold greater sensitivity than ethidium bromide staining, which can be used to quantify the products of multiplex PCR. The first method uses the DNA intercalating thiazole orange dye TOTO-1 to stain PCR products after 20 cycles. In the second method, fluorescein-12,2′-dUTP is incorporated into products during PCR as a fluorescent tag for subsequent quantitative dosage studies. Both methods label all multiplexed exons including the 506 bp exon 48 fragment that is difficult to detect and quantify by standard ethidium bromide staining. Using this approach, we determined DMD/BMD carrier status in 24 unrelated families using a fluorescent fragment analyzer. Analysis of fluorochrome-labeled PCR products facilitates quantitative multiplex PCR for gene-dosage analysis. © 1993 Wiley-Liss, Inc.     

杜氏进行性肌营养不良的临床实践指南

杜氏进行性肌营养不良(Duchemiemusculardystmphy.DMD)是最常见的X连锁隐性遗传性肌肉变性疾病,在男性新生儿中的发病率约为1/3500。DMD是由于Xp21.2区的抗肌萎缩蛋白基因(dystrop,DMD)突变所致,患者的主要临床表现包括进行性、对称性肌无力。由于呼吸肌和心肌受累,通常在30岁前死亡。通过基因检测,可以为93.1%的患者找到遗传学病因,为早期治疗和指导家庭成员的生育奠定基础,有利于改善患者的生存质量,预防这些家庭再次生育DMD患儿。本指南结合了国内外的相关研究和指南共识,总结了DMD相关的医学遗传学知识和临床处置要点,期望能给予临床工作者帮助,为DMD患者及其家庭提供规范的诊断、治疗和预防。     

Genetic epidemiology of Duchenne and Becker muscular dystrophy in Slovenia

Most population studies on Duchenne (DMD) and Becker (BMD) muscular dystrophies predated the discovery of the gene and its product dystrophin. The diagnosis of these conditions and consequent epidemiological estimates were therefore limited to clinical criteria. In our study of the Slovene population the prevalence and cumulative incidence of DMD and BMD were calculated by including additional diagnostic tests: deletion screening in the dystrophin gene as well as dystrophin immunocytochemistry. The minimal prevalence rates, 2.9/100000 for DMD, 1.2/100000 for BMD, and the minimal cumulative DMD incidence rate of 13.8/100000 are in the range of lower estimates compared to studies world-wide. However, we found a high BMD cumulative incidence rate of 5.7/100000 and a high proportion of BMD versus DMD cumulative incidence rate (41.3%). Our results imply that the epidemiological figures for BMD might have been underestimated in the past.