Mutations analysis of STK_(11) gene in Chinese families with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an autosomal dominant disease that is characterized by multiple gastrointestinal hamartomatous polyps and melanin spots on lips and buccal mucosa at young age[1,2]. Previous studies have demonstrated that PJS predisposes carriers to cancers of gastrointestinal tract, uterus, ovary, testis, breast and other extragastrointestinal organs[3—5]. The STK11 gene, encoding a serine/threonine kinase at chro-mosome 19p13.3, was identified in 1998 as the main causativ…     

导致人视网膜色素变性的RPGR基因突变

用ＰＣＲ－ＳＳＣＰ和ＤＮＡ测序的方法在两个ＸＬＲＰ家系ＲＰＧＲ基因的１２号和９号外显子内各发现一个未报道的突变。这两个突变引起了严重的视网膜色素变性。     

眼皮肤白化病患者的TYR基因突变类型初步研究

目的:对临床诊断为眼皮肤白化病(OCA)患者的TYR基因进行突变筛查,以了解我国大陆OCA患者TYR基因突变类型。方法:应用PCR技术扩增患者及其父母的TYR基因外显子、外显子-内含子交界区及启动子区,以DNA序列测定技术进行突变筛查与鉴定。结果:在8名患者的16个TYR等位基因内,查明9种突变;其中错义突变4种(R77Q、E294K、R299H和W 400L),无义突变2种(R116X和R278X),插入突变2种(929 insC和232 insGGG),剪切位点突变1种(IVS1-3 C>G)。结论:W 400L、R299H分别占本研究所检出全部OCA1突变等位基因的31.3%(5/16)和18.8%(3/16),可能为中国大陆人群中较常见的TYR基因突变类型。     

Early-onset Alzheimer's disease caused by mutations at codon 717 of the beta-amyloid precursor protein gene

A mutation at codon 717 of the beta-amyloid precursor protein gene has been found to cosegregate with familial Alzheimer's disease in a single family. This mutation has been reported in a further five out of approximately 100 families multiply affected by Alzheimer's disease. We have identified another family, F19, in which we have detected linkage between the beta-amyloid precursor protein gene and Alzheimer's disease. Direct sequencing of exon 17 in affected individuals from this family has revealed a base change producing a Val----Gly substitution, also at codon 717. The occurrence of a second allelic variant at codon 717 linked to the Alzheimer's phenotype supports the hypothesis that they are pathogenic mutations.     

Recurrent mutations in haemophilia A give evidence for CpG mutation hotspots

Haemophilia A is a common disorder of blood coagulation caused by a deficiency of factor VIII. It is inherited as an X-linked recessive trait, and one-third of all cases are thought to result from de novo mutations. The clinical severity of haemophilia A varies markedly among different families and a subset of the patients with severe disease develop antibodies against factor VIII, called inhibitors. Because of this heterogeneity, it is likely that many different molecular lesions result in haemophilia A. Indeed, of the nine mutations described to date, all appear to be unique changes. However in this study of 83 patients with haemophilia A we have identified two different point mutations, one in exon 18 and one in exon 22, that have recurred independently in unrelated families. Each mutation produces a nonsense codon by a change of CG to TG, and each occurred de novo on the X-chromosome donated by the maternal grandfather. These observations strongly support the view that CpG dinucleotides are mutation hotspots.     

耳聋基因GJB2的突变分析及其与临床相关性的研究

为了研究苏州地区耳聋人群中GJB2基因突变的频率、突变类型及这些突变与耳聋发生的相关性,收集苏州地区散发性耳聋患者样本106例,家系32个(父母和患儿),听力正常对照组样本100例,PCR-直接测序法分析GJB2基因的突变,PCR-RFLP方法对明确有235delC突变的家系作进一步分析.结果显示:106例散发性耳聋患者中发现了11种变异,235delC是最主要的突变,其中18例为235delC纯合性缺失.235delC纯合突变导致常染色体隐性遗传性耳聋,患者多为双耳重深度耳聋(双耳大于90 dB),发病年龄早;235delc和其他位于不同染色体上的突变形成双重杂合性突变时,也可以导致耳聋.PCR-RFLP方法可在明确235delC突变的患者家系中进行基因诊断.     

A frame-shift mutation in the cystic fibrosis gene.

Cystic fibrosis (CF) is a common recessive lethal genetic disorder, affecting 1 in 1,600 Caucasians. The disease causes defective regulation of chloride-ion transport in exocrine cells. Although in all CF families the disease is linked to a locus on chromosome 7q31, there is clinical heterogeneity in the severity of the disease and the age at which it is diagnosed. CF is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. A three-nucleotide deletion (delta F508) causing the loss of a phenylalanine residue in the tenth exon of the CFTR gene has been found on 70% of CF chromosomes. We have now characterized a CF family in which neither parent of the affected individual carries the common mutation, and identified a two-nucleotide insertion in the CF allele of the mother. The mutation introduces a termination codon in exon 13 of the CFTR gene at residue 821, and is predicted to result in the production of a severely truncated nonfunctional protein.     

A ferric-chelate reductase for iron uptake from soils

Iron deficiency afflicts more than three billion people worldwide, and plants are the principal source of iron in most diets. Low availability of iron often limits plant growth because iron forms insoluble ferric oxides, leaving only a small, organically complexed fraction in soil solutions. The enzyme ferric-chelate reductase is required for most plants to acquire soluble iron. Here we report the isolation of the FRO2 gene, which is expressed in iron-deficient roots of Arabidopsis. FRO2 belongs to a superfamily of flavocytochromes that transport electrons across membranes. It possesses intramembranous binding sites for haem and cytoplasmic binding sites for nucleotide cofactors that donate and transfer electrons. We show that FRO2 is allelic to the frd1 mutations that impair the activity of ferric-chelate reductase. There is a nonsense mutation within the first exon of FRO2 in frd1-1 and a missense mutation within FRO2 in frd1-3. Introduction of functional FRO2 complements the frd1-1 phenotype in transgenic plants. The isolation of FRO2 has implications for the generation of crops with improved nutritional quality and increased growth in iron-deficient soils.     

运用反向斑点杂交技术检测四川地区结核分枝杆菌katG基因315位点的突变

为了检测四川地区结核分枝杆菌KatG基因315位点的突变特点,并建立耐异烟肼结核分枝杆菌快速检测方法。运用反向杂交技术检测四川地区65株耐异烟肼和10株异烟肼敏感结核分枝杆菌KatG基因315位点的突变,并用DNA直接测序法验证杂交结果。结果显示在65株耐异烟肼结核分枝杆菌中,发现41株在KatG基因315位点发生突变,突变率最大的是AGC→ACC,占90％,其次是AGC→AAC和AGC→ATC突变。DNA序列测定结果进一步验证了反向杂交的结果。运用反向杂交技术检测四川地区结核分枝杆菌KatG基因315位点的突变的检出率和特异性分别是63％和100％。反向斑点杂交技术能快速有效地检测四川地区结核分枝杆菌KatG基因315位点的突变。     

头颈部鳞癌中p53-mdm2基因异常的研究

目的:检测头颈部鳞癌患者p53基因突变、mdm2基因扩增的状况,了解其与头颈部鳞癌患者的性别、鳞癌分级、淋巴结转移等的相关性及两异常基因的相关性。方法:收集50例行手术切除的头颈部鳞癌患者的新鲜肿瘤组织及其相应的癌旁正常组织,提取标本DNA;用PCR-SS-CP-银染法检测p53基因第5~8外显子的突变状况;用dPCR法检测mdm2基因扩增情况;采用SPSS 10.0统计软件包行2检验分析实验结果。结果:在50例头颈部鳞癌患者标本中,检测出17例存在p53基因突变,突变率为34%,所有的癌旁正常组织未发现p53基因突变;在50例鳞癌标本中检测出6例标本存在mdm2基因扩增,扩增率为12%,其中有一例同时存在p53基因突变;p53基因突变、mdm2基因扩增与患者的鳞癌分级、淋巴结转移、性别等相关性分析结果均无统计学意义(P>0.05)。结论:p53基因突变与mdm2基因扩增在头颈部鳞癌中较常见,可能是头颈部鳞癌发生发展的主要分子机制。     

Detection of a new mutation (1467-A) for the pedigree with mucopolysaccharidosis type Ⅱ from a Chinese family

Mucopolysaccharidosis type Ⅱ is of high genetic heterogeneity. PCR-DNA sequencing was used to study the mutation hot spots in the IDS gene of a Chinese MPS Ⅱ pedigree. A new mutation （1467-A） not yet reported worldwide was detected. This mutation located at 448th codon in the coding region of exon 9 deletes one “A” at the end of 1467 bp （cDNA）. The frame-shift mutation makes the peptide chain shorten from amino acids 550 to 459, probably altering the configuration of IDS enzyme protein remarkably and lowering the activation of IDS greatly. Therefore it is supposed to be the direct cause of the patient with MPS Ⅱ and to be a necessary premise for prenatal gene diagnosis.     

Preferential mutation of paternally derived RB gene as the initial event in sporadic osteosarcoma

Successive loss of function of both alleles of the retinoblastoma susceptibility gene (RB) on human chromosome 13 seems to be critical in the development of retinoblastoma and osteosarcoma. In cases where the tumour is familial and susceptibility is inherited, a mutation in one of the alleles is carried in the germline. We have recently shown that cytogenetically visible germline mutations are usually in the paternally derived gene. Such a bias would not be expected for sporadic (non-familial) tumours, where both mutations occur in somatic tissue, but there has been some indication of a bias towards initial somatic mutation in the paternally derived gene on chromosome 11 in sporadic Wilms tumour. We have now examined 13 sporadic osteosarcomas and find evidence which indicates that in 12 cases the initial mutation was in the paternal gene, suggesting the involvement of germinal imprinting in producing the differential susceptibility of the two genes to mutation.     

Nonsense mutation in the glucokinase gene causes early-onset non-insulin-dependent diabetes mellitus.

Maturity-onset diabetes of the young (MODY) is a form of non-insulin-dependent (type 2) diabetes mellitus (NIDDM) which is characterized by an early age at onset and an autosomal dominant mode of inheritance. Except for these features, the clinical characteristics of patients with MODY are similar to those with the more common late-onset form(s) of NIDDM. Previously we observed tight linkage between DNA polymorphisms in the glucokinase gene on the short arm of chromosome 7 and NIDDM in a cohort of sixteen French families having MODY. Glucokinase is an enzyme that catalyses the formation of glucose-6-phosphate from glucose and may be involved in the regulation of insulin secretion and integration of hepatic intermediary metabolism. Because the glucokinase gene was a candidate for the site of the genetic lesion in these families, we scanned this gene for mutations. Here we report the identification of a nonsense mutation in the gene encoding glucokinase and its linkage with early-onset diabetes in one family. To our knowledge, this result is the first evidence implicating a mutation in a gene involved in glucose metabolism in the pathogenesis of NIDDM.     

Germ-line transmission of a mutated p53 gene in a cancer-prone family with Li-Fraumeni syndrome

Tumour suppressor genes, whose usual function seems to be controlling normal cell proliferation, have been implicated in many inherited and sporadic forms of malignancies Much evidence supports the concept of tumour formation by loss-of-function mutations in suppressor genes, as predicted by the two-hit model of Knudson and DeMars. The suppressor gene, p53, is affected in such a manner by numerous mutations, which occur in a variety of human tumours. These mutations usually represent the loss of one allele and the substitution of a single base in the other. We have now analysed the p53 gene in a family affected by Li-Fraumeni syndrome, a rare autosomal dominant syndrome characterized by the occurrence of diverse mesenchymal and epithelial neoplasms at multiple sites. In some instances the neoplasms seem to be related to exposure to carcinogens, including ionizing radiation. The Li-Fraumeni family that we studied had noncancerous skin fibroblasts (NSF) with an unusual radiation-resistant phenotype. DNA derived from the NSF cells of four family members, spanning two generations, had the same point mutation in codon 245 (GGC----GAC) of the p53 gene. This mutation leads to substitution of aspartic acid for glycine in one of the regions identified as a frequent target of point mutations in p53. The NSF cell lines with the mutation also retained the normal p53 allele. This inherited p53 mutation may predispose the members of this family to increased susceptibility to cancer.     

广西巴马小型猪肌肉生长抑制素(Myostatin)cDNA克隆和序列分析

目的通过RT-PCR扩增广西巴马小型猪Myostatin cDNA序列,经过连接、转化、克隆测序后,与NCBI中发表的猪Myostatin序列进行同源性比较,分析广西巴马小型猪Myostatin的cDNA序列结构特点及与其他物种间的聚类关系,为日后构建Myostatin高效表达载体及进一步研究Myostatin对广西巴马小型猪肌肉生长的影响奠定基础。方法以广西巴马小型猪的肌肉组织总RNA为模板,应用逆转录-聚合酶链式反应(RT-PCR),利用合成的特异性引物,扩增得到巴马小型猪肌肉生长抑制素(Myostatin)cDNA的全序列。该扩增片段经纯化后,连接到pMD18-T载体上扩增,经一系列鉴定后,测序。结果本实验克隆到巴马小型猪Myostatin基因cDNA序列长度为1128 bp,与GenBank报道的猪Myostatin基因cDNA序列同源性高达99.7%,与人、奶牛、家鼠等物种的cDNA序列间同源性可达到92.3%以上,证明Myostatin基因具有较高的保守性。同时发现广西巴马小型Myostatin基因cDNA序列有三处存在碱基突变,两个为同义突变,一个为错义突变。     

新疆维吾尔族宫颈癌组织中C/EBPα第一外显子突变与HPV16感染的关系

为探讨新疆维吾尔族宫颈癌组织中C/EBPα第一外显子突变与HPV16感染的关系。收集46例新疆维吾尔族宫颈癌标本,采用基因测序方法检测C/EBPα第一外显子的突变,利用PCR扩增方法分析HPV16病毒的感染,进行统计学分析。结果发现C/EBPα第一外显子突变的患者HPV16病毒感染率高。且C/EBPα第一外显子突变的患者与未突变的患者的HPV16病毒的感染率存在显著性差异。McNemanr检验P0.05双侧。由此可知,新疆维吾尔族宫颈癌组织中C/EBPα基因第一外显子突变与HPV16病毒的感染相关。C/EBPα第一外显子突变可能是导致宫颈癌的一个重要因素。