应用连锁不平衡检验法进行单纯性先天性心脏病易感基因 …

将人类单纯性先天性心脏病（ｃｏｎｇｅｎｉｔａｌｈｅａｒｔｄｅｆｅｃｔ，ＣＨＤ）易感基因初步定位，为进一步对其克隆奠定基础，方法在胚胎心脏发育调控相关基因－ＨＯＸ基因Ａ簇、Ｂ簇所在在的染色体区域７ｐ１４－１５、１７ｑ２１内选择３个微卫星ＤＮＡ标记Ｄ７Ｓ１８０８、Ｄ７Ｓ６７３、Ｄ１７Ｓ７９１，应用荧光标记聚合酶边反应技术扩增微卫星征 段，对３９个单纯性ＣＨＤ核心家系的１１２名成员进行基因型，并进行遗传     

由肌肉聚多糖基因突变所致的肌营养不良的遗传流行病学

常染色体隐性肢带肌营养不良（ＬＧＭＳ）是一组遗传异质性肌肉疾病，其特征为进行性近端肢肌无力。已定位６个不同基因位点，并且在文献中已证明编码肌肉聚多糖复合物组成成分（α－，β－，γ－和σ－肉聚多糖）基因的致病性突变。原发性“肌肉聚多糖病”受累的ＬＧＭＤ...     

骨肉瘤的分子遗传学研究进展

近几年骨肉瘤的分子遗传专学研究表明，骨肉瘤更趋向是一种遗传病。其分子病理的基础主要是肿瘤抑制基因的失活与原癌．基因的激活。已发现与骨肉瘤发生、发展及预后有关的基因包括ＲＢ、Ｐ５３肿瘤抑制基因及ｃ－ｍｙｃ、ｃ－ｆｏｓ、ｃ－ｓｉｓ，ｃ－ｒａｆ－１、ＳＡＳ、ｇｌｉ和ＭＤＭ２原癌基因。ＲＢ基因第一次突变多来自父方。Ｐ５３基因突变集中在第一内含子。染色体３ｑ、１３ｑ、１７ｐ和１８ｑ的频发性等位基因缺失提示，除位于１３ｑ的ＲＢ基因及位于１７ｐ的Ｐ５３基因外，至少还有两个与骨肉瘤发生有关的抗肿瘤抑制基因分别位于３ｑ和１８ｑ。具有Ｐ５３基因的等位缺失和／或ＭＤＭ２基因扩增的骨肉瘤更易发生肺转移，是判断骨肉瘤预后的重要指标。     

云南经典PKU基因外显子4,10和12突变的检测

目的：探讨云南经典ＰＫＵ的基因突变特征。方法：应用ＰＣＲˉＳＣＰ和ＰＣＲ－循环测序技术对云南１３个ＰＫＵ家系１４名患儿的ＰＡＨ基因外显子４、１０和１２进行了检测。结果：Ｒ４１３Ｐ、Ｗ３２６Ｘ的突变频率分别是７１４％、３５７％；Ａ／Ｃ杂合频率是１０７１％，同时检测到外显子４的３种异常带型。结论：云南ＰＫＵ患者的基因突变不同于北方人群，Ｐ４１３Ｐ、Ａ／Ｃ杂合率约为北方人群突变的１／２；Ｗ３２６Ｘ则高于北方人群；外显子４的突变也可能高于北方人群。     

用简并寡核苷酸引物构建人类染色体区带特异性探针池的技术

目的建立快速有效构建人类染色体区带特异性探针池及其文库的技术。方法显微切割人类染色体３ｐ２３－ｐ２６，３ｑ２１－ｑ２２，４ｐ１２－ｐ１６区带，用简并寡核苷酸引物－ＰＣＲ（ｄｅｇｅｎｅｒａｔｅｏｌｉｇｏｎｕｃｌｅｏｔｉｅｄｐｒｉｍｅｒｅｄ－ＰＣＲ，ＤＯＰ－ＰＣＲ）扩增，并用荧光原位杂交（ｆｌｕｏｒｅｓｃｅｎｃｅｉｎｓｉｔｕｈｙｂｒｉｄｉｚａｔｉｏｎ，ＦＩＳＨ）检测扩增产物来源，再将区带特异性扩增产物克隆于ｐＵＣ１９载体构建区带特异性文库，以及用α－３２ＰＡＴＰ标记的ｇＤＮＡ行菌落原位杂交。结果经ＦＩＳＨ证实，３ｐ２３－ｐ２６，３ｑ２１－ｑ２２，４ｐ１２－ｐ１６探针池均在切割相应区带出现特异性信号。其中３ｑ２１－ｑ２２获得的１．２×１０４个阳性克隆。随机分析３０个含插入片段的白色菌落，其插入片段平均约４２０ｂｐ。２２０个白色克隆菌落原位杂交示单拷贝和低度重复序列占８１％（１７８／２２０）。结论改进的显微切割结合ＤＯＰ－ＰＣＲ为人类染色体探针池及文库构建建立了一个简易、高效的方法，这将有助于基因克隆和人类基因的全序列分析。     

Wilson病家系ATP7B基因第18外显子突变及多态

目的：检测中国人Ｗｉｌｓｏｎ病（ＷＤ）基因的第１８外显子（ｅｘｏｎ１８）突变及多态。方法：应用多聚酶链反应－单链构象多态性（ＰＣＲ－ＳＳＣＰ）技术，分析１６个ＷＤ家系５４例个体和１８例正常人ＡＴＰ７Ｂ基因ｅｘｏｎ１８分子结构改变。结果：在ＷＤ家系中发现有３种单链构象，其中１种为正常构象，１种为突变，另１种可能为正常ＤＮＡ多态；１７例ＷＤ患者及其３７例一级亲属中分别检出突变者１０例和１１例，突变率分别为２９．４％和１４．９％。其中一级亲属检出的突变者中有３例经血清铜氧化酶及眼科Ｋ－Ｆ环检查证实为ＷＤ症状前患者。结论：ｅｘｏｎ１８是中国人ＷＤ基因突变热点之一，大多数ＷＤ患者为复合杂合子；应用ＰＣＲ－ＳＳＣＰ技术分析ｅｘ－ｏｎ１８是一种有效的ＷＤ基因筛选方法，也可为无家族史的ＷＤ可疑者提供诊疗依据     

家族性肌萎缩性侧索硬化症的研究进展

本文阐述了ＦＡＬＳ为常染色体显性遗传性疾病及其临床特点。通过微小卫星ＤＮＡ标记进行遗传连锁分析，确定本病基因定位于２１号染色体上。认为发病原因与Ｃｕ／ＴｎＳｏＤ－１基因突变有关。对寻找有效的治疗和预防方法提供了新的依据。     

用非同位素PCR—SSCP方法检测石蜡包埋乳腺癌P53基因点突变

应用－非同位素ＰＣＲ－ＳＳＣＰ方法检测常规石蜡包埋乳腺癌组织中Ｐ５３基因点突变，结果显示６０例乳腺癌中，１４例有异常电泳带，表明这些病例相应ＤＮＡ片段中发生了点突变，其中４例位于第５－６外显子，３例位于第７外显子，７例位于第８外显子，免疫组化法检测突变型Ｐ５３蛋白的表达，１３例为阳性，其中１１例ＳＳＣＰ检测到异常电泳带，另２例突变可能发生在所检测的基因片段以外，而５例ＳＳＣＰ分析发现基因突变者，免     

PCR—SSCP银染方法检测BRCA1基因核苷酸部位2731的多态性

乳腺癌易感基因ＢＲＣＡ１是肿瘤抑制基因之一，它定位于染色体１７ｑ２１，编码一个尚不清楚的蛋白质，分子量２０万道尔顿，含有１８６３个氨基酸。已发现ＢＲＣＡ１基因的２００个以上突变及３０外以上多态位点。本文用ＰＣＲ－ＳＳＣＰ银染方法检测其核苷酸蝇位２７３１的多态性，具有经济，快速，灵敏，相对简单易行和可靠的优点。     

中国人β地中海贫血的分子基础及产前诊断

β地中海贫血是一组高度异质性的遗传性血液病。中国人中已发现２１种β地贫基因，其突变类型包括碱基替代、小的缺失和插入。我国南方常见的类型是密码子（ＣＤ）４１－４２（－ＴＣＴＴ）移码突变，ＩＶＳ２ｎｔ６５４（Ｃ→Ｔ）突变，ＣＤ１７（Ａ→Ｔ）突变，ＴＡＴＡ盒ｎｔ－２８（Ａ→Ｇ）突变和ＣＤ７１－７２（＋Ａ）移码突变，其基因频率分别为４１．６％、２１．８％、１８．０％和８．０％及３．９％。     

Main clinical features of the three mapped autosomal recessive limb-girdle muscular dystrophies and estimated proportion of each form in 13 Brazilian families.

Autosomal recessive limb-girdle muscular dystrophies (AR LGMD) represent a group of muscle diseases with a wide spectrum of clinical signs, varying from very severe to mild. Four different loci that when mutated cause the AR LGMD phenotype have been mapped or cloned or both: in two of them the linked families seem to have a relatively mild phenotype (LGMD2a and LGMD2b), in the third one the reported linked families show a more severe clinical course (LGMD2c), while mutations in the fourth locus may cause severe or mild phenotypes (LGMD2d). The relative proportion of each of these genetic forms among the LGMD families and whether there are other genes that when mutated cause this phenotype is unknown. The closest available informative markers for each of the mapped AR LGMD genes have been tested in 13 Brazilian families with at least three affected patients. The findings from the present report confirm non-allelic heterogeneity for LGMD and suggest that in our population about 33% of the LGMD families are caused by mutations in the 15q gene, 33% in the 2p gene, 17% by mutations in the adhalin gene, and less than 10% may be by mutations at the 13q locus. They also suggest that there is at least one other gene responsible for this phenotype. In addition, the main clinical features of the different forms are discussed.     

Mutational diversity and hot spots in the alpha-sarcoglycan gene in autosomal recessive muscular dystrophy (LGMD2D).

Sarcoglycanopathies are a genetically heterogeneous group of autosomal recessive muscular dystrophies in which the primary defect may reside in any of the genes coding for the different partners of the sarcolemmal sarcoglycan (SG) complex: the alpha-SG (LGMD2D at 17q21.2), the beta-SG (LGMD2E at 4q12), the gamma-SG (LGMD2C at 13q12), and the delta-SG (LGMD2F at 5q33). We report a series of 20 new unrelated families with 14 different mutations in the alpha-SG gene. Along with the mutations that we previously reported this brings our cohort of patients with alpha-sarcoglycanopathy to a total of 31 unrelated patients, carrying 25 different mutations. The missense mutations reside in the extracellular domain of the protein. Five of 15 missense mutations, carried by unrelated subjects on different haplotype backgrounds and of widespread geographical origins, account for 58% of the mutated chromosomes, with a striking prevalence of the R77C substitution (32%). The severity of the disease varies strikingly and correlates at least in part with the amount of residual protein and the type of mutation. The recurrent R284C substitution is associated with a benign disease course.     

Evidence of genetic heterogeneity in the autosomal recessive adult forms of limb-girdle muscular dystrophy following linkage analysis with 15q probes in Brazilian families.

The autosomal recessive limb-girdle muscular dystrophies (LGMD) represent a heterogeneous group of diseases which may be characterised by one or more autosomal loci. A gene at 15q has recently been found to be responsible for a mild form of LGMD in a group of families from the isolated island of Réunion, now classified as LGMD2. Based on results of eight out of 11 large Brazilian LGMD families of different racial background (which were informative for the closest available probe to the LGMD2 gene), we confirmed linkage to the LGMD2 gene at 15q in two of these families and exclusion in six others. These data provide the first evidence of genetic heterogeneity for the autosomal recessive limb-girdle muscular dystrophies.     

Seven autosomal recessive limb-girdle muscular dystrophies in the Brazilian population: from LGMD2A to LGMD2G

The autosomal recessive limb-girdle muscular dystrophies (AR-LGMDs) are a heterogeneous group of disorders of progressive weakness of the pelvic and shoulder girdle musculature. The clinical course is characterized by great variability, ranging from severe forms with onset in the first decade and rapid progression resembling clinically Xp21 Duchenne muscular dystrophy (DMD) to milder forms with later onset and slower course. Eight genes are mapped for the AR-LGMDs; they are: LGMD2A (CAPN3) at 15q, LGMD2B (dysferlin) at 2p, LGMD2C (gamma-SG) at 13q, LGMD2D (alpha-SG) at 17q, LGMD2E (beta-SG) at 4q, LGMD2F (6-SG) at 5q, LGMD2G at 17q, and more recently LGMD2H at 9q. The LGMD2F (delta-SG) and LGMD2G genes were mapped in Brazilian AR-LGMD families. Linkage analysis in two unlinked families excluded the eight AR-LGMD genes, indicating that there is at least one more gene responsible for AR-LGMD. We have analyzed 140 patients (from 40 families) affected with one of seven autosomal recessive LGMD loci, that is, from LGMD2A to LGMD2G. The main observations were: 1) all LGMD2E and LGMD2F patients had a severe condition, but considerable inter- and intra-familial clinical variability was observed among patients from all other groups; 2) serum CK activities showed the highest values in LGMD2D (alpha-SG) patients among sarcoglycanopathies and LGMD2B (dysferlin) patients among nonsarcoglycanopathies; 3) comparison between LGMD2A (CAPN3) and LGMD2B (dysferlin) showed that the first have on average a more severe course and have calf hypertrophy more frequently (86% versus 13%); and 4) inability to walk on toes was observed in approximately 70% of LGMD2B patients.     

Asymptomatic carriers for homozygous novel mutations in the FKRP gene: the other end of the spectrum

Autosomal recessive limb-girdle muscular dystrophy linked to 19q13.3 (LGMD2I) was recently related to mutations in the fukutin-related protein gene (FKRP) gene. Pathogenic changes in the same gene were detected in congenital muscular dystrophy patients (MDC1C), a severe disorder. We have screened 86 LGMD genealogies to assess the frequency and distribution of mutations in the FKRP gene in Brazilian LGMD patients. We found 13 Brazilian genealogies, including 20 individuals with mutations in the FKRP gene, and identified nine novel pathogenic changes. The commonest C826A European mutation was found in 30% (9/26) of the mutated LGMD2I alleles. One affected patient homozygous for the FKRP (C826A) mutation also carries a missense R125H change in one allele of the caveolin-3 gene (responsible for LGMD1C muscular dystrophy). Two of her normal sibs were found to be double heterozygotes. In two unrelated LGMD2I families, homozygous for novel missense mutations, we identified four asymptomatic carriers, all older than 20 years. Genotype-phenotype correlation studies in the present study as well as in patients from different populations suggests that the spectrum of variability associated with mutations in the FKRP gene seems to be wider than in other forms of LGMD. It also reinforces the observations that pathogenic mutations are not always determinant of an abnormal phenotype, suggesting the possibility of other mechanisms modulating the severity of the phenotype that opens new avenues for therapeutic approaches.     

Limb-girdle muscular dystrophy 2I: phenotypic variability within a large consanguineous Bedouin family associated with a novel FKRP mutation

Limb-girdle muscular dystrophies (LGMDs) represent a group of diseases characterized mainly by muscle wasting of the upper and lower limbs, with a wide range of clinical severity. The clinical heterogeneity is paralleled by molecular heterogeneity; each of the 10 forms of autosomal-recessive LGMD recognized to date is caused by mutations in a distinct gene. In a large consanguineous Bedouin tribe living in northern Israel, 15 individuals affected by LGMD demonstrate an autosomal recessive pattern of inheritance. A genome-wide screen followed by fine mapping in this family revealed linkage to a region on chromosome 19 harboring the fukutin-related protein gene (FKRP), with a maximal LOD score of 4.8 for D19S902. FKRP, encoding a putative glycosyltransferase, has been implicated in causing congenital muscular dystrophy 1C (MDC1C), and has recently been shown to be mutated in LGMD2I. We identified a novel missense mutation in exon 4 of the FKRP gene in all the patients studied. Although all affected individuals were homozygous for the same mutation, a marked phenotypic variability was apparent within the family. This finding may suggest a role of modifier genes and environmental factors in LGMD2I. Moreover, the demonstration that an identical, novel mutation in the FKRP gene can cause a muscle disease of either a congenital onset or of a later onset within a single family provides clinical support to the molecular evidence, suggesting that MDC1C and LGMD2I are overlapping ends of one and the same entity.     

Maternal uniparental disomy of chromosome 4 in a patient with limb-girdle muscular dystrophy 2E confirmed by SNP array technology

The limb-girdle muscular dystrophies (LGMDs) are a heterogenous group of diseases characterized by shoulder-girdle and pelvic muscle weakness and wasting. LGMD 2E is an autosomal recessively inherited form of the disease caused by mutations in the β-sarcoglycan (SGCB) gene located at 4q12. In this report, we describe a patient who demonstrates non-Mendelian inheritance of a homozygous missense mutation in SGCB resulting in disease expression. A combination of single-nucleotide polymorphism (SNP) array technology and microsatellite analysis revealed the occurrence of maternal uniparental disomy (UPD) for chromosome 4 in the patient. As a consequence of segmental isodisomy at 4q12, the patient inherited two identical SGCB alleles carrying a missense mutation predicted to result in abnormal protein function. SNP array technology proved to be an elegant means to determine the most probable mechanism of UPD formation in this case, and enabled us to determine the location of recombination events along chromosome 4. In our patient, UPD likely arose from a trisomy rescue event due to maternal meiotic non-disjunction that we speculate may have been caused by abnormal recombination at the pericentromeric region. Maternal UPD 4 is a rare finding, and to our knowledge this is the first reported case of UPD in association with LGMD.     

Identification of mutations in the gene encoding lamins A/C in autosomal dominant limb girdle muscular dystrophy with atrioventricular conduction disturbances (LGMD1B)

LGMD1B is an autosomal dominantly inherited, slowly progressive limb girdle muscular dystrophy, with age-related atrioventricular cardiac conduction disturbances and the absence of early contractures. The disease has been linked to chromosome 1q11-q21. Within this locus another muscular dystrophy, the autosomal dominant form of Emery-Dreifuss muscular dystrophy (AD-EDMD) has recently been mapped and the corresponding gene identified. AD-ADMD is characterized by early contractures of elbows and Achilles tendons and a humero-peroneal distribution of weakness combined with a cardiomyopathy with conduction defects. The disease gene of AD-EDMD is LMNA which encodes lamins A/C, two proteins of the nuclear envelope. In order to identify whether or not LGMD1B and AD-EDMD are allelic disorders, we carried out a search for mutations in the LMNA gene in patients with LGMD1B. For this, PCR/SSCP/sequencing screening was carried out for the 12 exons of LMNA on DNA samples of individuals from three LGMD1B families that were linked to chromo-some 1q11-q21. Mutations were identified in all three LGMD1B families: a missense mutation, a deletion of a codon and a splice donor site mutation, respectively. The three mutations were identified in all affected members of the corresponding families and were absent in 100 unrelated control subjects. The present identification of mutations in the LMNA gene in LGMD1B demonstrates that LGMD1B and AD-EDMD are allelic disorders. Further analysis of phenotype-genotype relationship will help to clarify the variability of the phenotype observed in these two muscular dystrophies.     

C283Y mutation and other C‐terminal nucleotide changes in the γ‐sarcoglycan gene in the Bulgarian gypsy population

Sarcoglycanopathies, affecting the dystrophin‐associated sarcoglycan (SG) complex, are a heterogeneous group of neuromuscular disorders. A subgroup of these disorders, limb‐girdle muscular dystrophy type 2C (LGMD2C) is an autosomal recessive disorder, clinically manifested as an early onset, severe Duchenne‐like muscular dystrophy. LGMD2C is caused by mutations in the γ‐SG gene, localized on 13q12. Recently, a number of mutations have been described in that gene, among which C283Y, a “private” Gypsy mutation (eight codons before the 3′ end of the gene) is detected. In this article, we report on a single‐strand conformation polymorphism (SSCP) method for fast C283Y mutation detection, using direct dry blood spot amplification. The method permits a large number of samples to be easily screened. To check heterozygote carriers of C283Y mutation among Gypsy population in Bulgaria, the SSCP analysis was applied on 400 Gypsy newborns from northeast Bulgaria. Our results show 2.25% of heterozygosity, which means that 1 in 50 Gypsies carries the mutation. Moreover, new SSCP migration patterns were detected that revealed two polymorphisms still unavailable in the literature. One of these changes was 984G→A, leading to substitution of conserved serine at position 287 with asparagine and the second one is 1049C→G at the 3′ UTR (untranslated region). The present data could help the understanding the role of these sequences for the protein function. Hum Mutat 14:40–44, 1999. © 1999 Wiley‐Liss, Inc.     

The most common mutation in FKRP causing limb girdle muscular dystrophy type 2I (LGMD2I) may have occurred only once and is present in Hutterites and other populations

Limb girdle muscular dystrophy (LGMD) is common in the Hutterite population of North America. We previously identified a mutation in the TRIM32 gene in chromosome region 9q32, causing LGMD2H in approximately two-thirds of the 60 Hutterite LGMD patients studied to date. A genomewide scan was undertaken in five families who did not show linkage to the LGMD2H locus on chromosome 9. A second LGMD locus, LGMD2I, was identified in chromosome region 19q13.3, and the causative mutation was identified as c.826C>A (L276I), a missense mutation in the FKRP gene. A comparison of the clinical characteristics of the two LGMD patient groups in this population reveals some differences. LGMD2I patients generally have an earlier age at diagnosis, a more severe course, and higher serum creatine kinase (CK) levels. In addition, some of these patients show calf hypertrophy, cardiac symptoms, and severe reactions to general anesthesia. None of these features are present among LGMD2H patients. A single common haplotype surrounding the FKRP gene was identified in the Hutterite LGMD2I patients. An identical core haplotype was also identified in 19 other non-Hutterite LGMD2I patients from Europe, Canada, and Brazil. The occurrence of this mutation on a common core haplotype suggests that L276I is a founder mutation that is dispersed among populations of European origin.