【作者】 张敏；

【导师】 齐名；

【作者基本信息】 江苏大学 ， 临床检验诊断学， 2010， 硕士

【摘要】 单核苷酸多态性(single nucleotide polymorphism,SNP)指存在于某一(些)群体、正常个体的基因组DNA中单碱基的序列差异,是生物体基因组中存在最简单也是最广泛的多态形式,人类遗传基因的多态性在遗传信息上的本质表现,90%以上是由SNP所引起的。其具有分布广,数目多,且相对稳定的存在于染色体上等特点。SNP的产生可能会造成蛋白质表现的改变,所以SNP也成为影响人类体质的关键,使人可能特别容易或特别不容易患上某些疾病,或使得对于治疗药物的反应性有所差异。当前人们正致力于疾病基因背景的探索,SNP由于其在基因遗传研究方面所具备的优势,成为继人类基因组计划完成之后又一研究新热点。系统性红斑狼疮(systemic lupus erythematosus SLE)是一种慢性自身免疫性疾病,其特征表现为多种自身抗体产生并引起免疫复合物沉积导致多系统损伤,从免疫学角度,SLE是针对多种自身抗原,主要为核内抗原如:DNA、组蛋白和核小体等产生的自身免疫反应,其中DNA是最重要的抗原之一。DNA损伤普遍存在,而细胞也己进化产生复杂的DNA修复体系来修复损伤,保持基因组的完整性。研究证明,DNA修复基因的单核苷酸多态(SNP)具有不保守的氨基酸置换作用,基因一般氨基酸取代的变异体可影响蛋白质的功能、修复能力。个体的DNA修复能力则与其DNA修复基因的多态基因型有密切关系。DNA修复缺陷与一些DNA修复蛋白功能完全缺失的基因突变相关,而更多的则是通过基因的遗传多态导致修复功能的不同。X线修复交叉互补基因1(X-ray repair cross-complementing 1,XRCC1)是一种重要的DNA修复基因,参与DNA单链断裂和碱基损伤修复,位于人染色体19q13.2-13.3,编码区单核苷酸多态位点导致相应的氨基酸改变。本实验采用病例一对照研究的方法,提取样本基因组DNA,以等位基因特异性聚合酶链反应(allele specific polymerase chainreaction,AS-PCR)技术为基础分析目的基因XRCC1多态位点Arg194Trp、Arg280His和Arg399G1n的基因型分布频率,进而发现高危基因型,探讨其与系统性红斑狼疮发生及与临床表现、实验室指标的关联程度,旨在了解个体多态基因型,在系统性红斑狼疮发生的病因学机制中的作用,为高危人群的筛检和干预提供依据;同时其与临床表现和实验室指标的关联,对基因诊断个体化有导向作用。目的:分析中国汉族人群SLE患者与正常对照人群中XRCC1基因单核苷酸多态性分布,探讨XRCC1基因单核苷酸多态性对SLE易感性的影响及与临床表现、实验室指标的关联程度。方法:用AS-PCR方法,测定39例中国汉族SLE患者和40例中国汉族健康者的XRCC1多态位点Arg194Trp、Arg280His和Arg399G1n的SNP型别。结果:(1)SLE组和正常对照组对比,XRCC1多态位点Arg399G1n等位基因和基因型频率分布具显著差异(P＜0.05)。XRCC1等位基因Arg399G1nGA+AA患病风险率增加[OR=3.92;95%CI(1.51-10.18)]。2,Arg194TrpCT+TT基因型在SLE患者出现血液损害的频率较低,在SLE患者出现SS-A抗体阳性频率较高。结论:XRCC1等位基因Arg399G1n基因多态性与SLE发生有一定的相关性,XRCC1等位基因Arg399G1nGA+AA可能为SLE的易感基因型。XRCC1多态位点与SLE患者自身抗体的产生、血液系统损害具有一定的相关性。更多还原

【Abstract】 Single nucleotide polymorphism(SNP) is defined as single base sequence disparity of genome DNA in certain colonia or normal individuals,which is the simplist and most extensive polymorphic type in genome of biosystem.Over 90%of the essential qualities reflection on genetic information of human gene polymorphism was due to SNP characterized as extensive distribution,large quantity and relative stability.The occurrence of SNP may lead to the change of protein sequence or conformation and SNP is considered to be critical to human body constitution resulting in individual variation in liability to certain disease and reaction to certain treatment.Nowadays,researcheres are making great efforts in the exploration of the background of human disease-associated genes,SNP become a hot spot due to its advantages in heredity research.Systemic lupus erythematosus(SLE) is a chronic autoimmune disease characterized by the production of diverse autoantibodies, resulting in immune complex deposition and tissue and organ damage. From the perspective of immunology,SLE is the autoirnrnune response, against the many self-antigens,mainly nuelear antigens such as DNA, Protein and nuclear bodies and so on.DNA has been considered to be one of the most important.DNA repair system continuously monitor chromosome to protect the integrity of DNA.The single nucleotide polymorphisms of DNA repair genes have unconservative amino acid replacements,of which the mutants can change the function of protein, repair capability.The DNA repair capability of individual is close to the polymorphic genotypes.The defect of DNA repair capability is connected with the function deletion of DNA repair protein resulting from gene mutations,mostly with the different repair capability from genetic polymorphisms.The X-ray repair cross-complementing 1(XRCC1) plays a critical role in repair of single-strand breaks and base damage,and is located on human chromosome 19q13.2-13.3.In encoding area,single nucleotide polymorphism results in the corresponding change of amino acid.A case-control study was conducted to test the allele frequencies and genotype frequencies of XRCC1 Arg194Trp,Arg399Gln and Arg399Gln by AS-PCR,from which risk genotypes can be found.It can be helpful to analyze possible mechanism of systemic lupus erythematosus and their roles to discuss the association between the risk genotypes and systemic lupus erythematosus and the interaction between genotypes and clinical or laboratory feature,which can be used in studying the etiology of systemic lupus erythematosus.The relations between genotypes and clinical or laboratory feature,will provide an evidence for individual gene diagnosis.Objective:To explore frequencies and single nucleotide polymorphisms distribution of XRCC1 gene,and analysis the susceptibility to systemic lupus erythematosus in Chinese Han population and the interaction between genotypes and clinical or laboratory feature.Methods:allele specific polymerase chain reaction(AS-PCR)was used to comparatively study the SNP in XRCC1 Arg194Trp、Arg399Gln and Arg399Gln in 39 patients with SLE and 40 randomly selected,unrelated healthy controls of Chinese Han population. Results:(1)Genotype and allele frequeneies of XRCC1 Arg399Gln were signifieantly different between the SLE cases and controls(P＜0.05), Arg399GInGA+AA was associate with the inereased risk of SLE [OR=3.92;95%CI(1.51-10.18)];(2) Hematological system damage ratio is lower in Arg194Trp CT+TT genotype SLE patients than the others. Anti SS-A antibody positive rate is increase in Arg194Trp CT+TT genptype SLE patients than the other.Conclusion:Genotype and allele frequeneies of XRCC1 Arg399Gln polymorphism and the incidence of SLE have some relevance.The genotype Arg399Gln GA+AA possiblely is the susceptible gene of SLE. It is related between the SNP in XRCC1 Arg194Trp and autoantibody Production,hematological system damage in SLE Patients.更多还原