【作者】 魏玉保；

【导师】 陈蕊雯；

【作者基本信息】 第二军医大学 ， 遗传学， 2010， 硕士

【摘要】 强直性脊柱炎(Ankylosing spondylitis, AS)在中国人群发病率约0.3%。AS是一种复杂性状疾病,现已证实AS与6号染色体上HLA-B27基因强相关,除此之外通过全基因组连锁和关联分析,提示染色体上其它区域还存在很多强关联性的易感基因。类风湿关节炎(rheumatoid arthritis, RA)是一种常见疾病,世界平均患病率为1%左右,在中国的患病率为0.1%-2%。通过家系、双生子研究证明,遗传因素在这两种疾病的发病机理中均发挥了重要作用。随着人们对AS和RA抗体谱的深入认识,提出了瓜氨酸相关自身免疫系统概念,此系统可能在AS和RA的发病和发展过程中起重要作用,并且与病情和预后有关。催化肽中精氨酸残基转化成瓜氨酸残基的过程叫做瓜氨酸化。瓜氨酸化由肽基精氨酸脱亚胺酶(peptidylarginine deiminase, PADI)完成。PADI4最早在日本人中报道与RA存在强关联。PADI4基因单核苷酸多态性位点在欧美、亚洲乃至东亚不同族群中有着极大分异,在中国汉族人中对这一基因的单核苷酸多态性尚无深入的研究。已有研究结果揭示PADI4蛋白可能作为自身抗原在AS和RA的发病和病理过程中起重要作用。我们通过对AS和RA易感基因PADI4的连锁不平衡分析,希望能对AS和RA的发病机制有进一步的认识,为AS和RA的诊断和治疗提供新的理论依据。在实验室以往的候选基因关联分析基础上,本课题对汉族人群PADI4的单核苷酸多态性(single-nucleotide polymorphisms, SNPs)进行深入的研究。我们在316个AS患者和439个正常对照中,用直接测序法对PADI4上的5个SNPs-PADI4-89 A/G (rs11203366), PADI4-90 (rs11203367) C/T, PADI4-92 (rs874881) C/G, PADI4-94 C/T (rs2240340)和PADI4-104 C/T(rs1748033)进行了基因分型。结果显示5个SNPs的主等位基因频率在病例-对照中分别是0.57 vs 0.60,0.57 vs 0.59,0.57 vs 0.57, 0.45 vs 0.42,0.61 vs 0.62.两个主单倍型ACCGC和GTGAT的频率之和占了病例组的85.7%和对照组的83.7%。经群体遗传学分析,这5个SNP位点的等位基因频率、基因型频率和单倍型频率在患者和对照组中没有显著性差异(P>0.05)。研究结果表明在中国汉族人群中PADI4基因与AS没有关联。同时我们在378个RA病例和204个正常对照中,对PADI4上的5个SNPs-PADI4-89 A/G (rs11203366), PADI4-90 (rsl 1203367) C/T, PADI4-92 (rs874881) C/G, PADI4-94 C/T(rs2240340)和PADI4-104 C/T (rs1748033)进行了基因分型。5个SNPs的等位基因频率在病例-对照中依次是0.55 vs 0.56,0.55 vs 0.57,0.57 vs 0.62,0.54 vs 0.55,0.60 vs 0.60。两个主单倍型ACCCC和GTGTT的频率之和占了病例组的76.8%和对照组的81.5%。群体遗传学分析显示这5个SNP位点的等位基因频率、基因型频率和单倍型频率在患者和对照组中没有显著差异(P>0.05)。结果表明在中国汉族人群中PADI4基因不是RA的易感基因。不同种族人群间尽管在性别构成,患者年龄及类风湿因子阳性率上相似,由某些潜在易感基因决定的疾病表型是有显著差异的。这可能与等位基因的异质性和遗传背景差异有关。基因间的相互作用也在一定程度上影响了关联分析的结果,所以有必要检视PADI4信号通路上其它基因与AS和RA易感性的关联。在中国汉族人群中,PADI4不是AS和RA的易感基因,而它们与其他自身免疫性疾病是否相关,需要进一步更细致的研究。更多还原

【Abstract】 Ankylosing spondylitis (AS) is a debilitating chronic inflammatory condition with a high degree of familiality and heritability that primarily affects spinal and sacroiliac joints. The elucidation of the genetic determinants will lead to a better understanding of disease pathogenesis, and enhanced prediction of disease risk, diagnosis, prognosis, and therapy. The cause of ankylosing spondylitis (AS) still remains unelucidated. Both genetic and environmental factors are suspected playing an important role in AS development. Peptidyl arginine deiminase, type IV (PADI4) is a member of a gene family which encodes enzymes responsible for the conversion of arginine to citrulline residues playing a pivotal role in bone mass and metabolism. Previously a strong linkage between PADI4 polymorphism and rheumatoid arthritis (RA) has been found in Japanese patients but there were very rare association study between PADI4 and AS.In this study a total of 316 Chinese AS patients of Han nationality and 439 healthy controls were recruited. Five single-nucleotide polymorphisms (SNPs), PADI4-89 A/G (rs11203366), PADI4-90 (rs11203367) C/T, PADI4-92 (rs874881) C/G, PADI4-94 C/T (rs2240340) and PADI4-104 C/T (rs1748033), in the PADI4 gene were selected and the allele frequencies between cases and controls were assessed. The major allele frequency of the five SNPs in case-control is 0.57 vs 0.60,0.57 vs 0.59,0.57 vs 0.57,0.45 vs 0.42,0.61 vs 0.62, respectively. The frequency sum of the two major haplotype (ACCGC, GTGAT) was accounded 85.7% in cases and 83.7% in controls. No significant differences in the frequency of PADI4 alleles, genotypes and haplotypes were observed between the cases and controls. PADI4 gene polymorphism is not associated with ankylosing spondylitis in Chinese Han population.Rheumatoid arthritis (RA) is a complex disease which arises from interplay between genetic and environmental factors. Despite lots of advances in the treatment was achieved recently, the etiology of RA still remains elusive. Non-major histocompatibility complex genes have been identified and novel technologies promise that a more thorough examination of the rest of the genome will soon elucidate the genetic basis of this disease. This PADI4 gene is commonly expressed in RA synovial tissues reported by some studies. In this study we also investigate the five SNPs as PADI4 as PADI4-89 (rsl 1203366), PADI4-90 (rs11203367), PADI4-92 (rs874881), PADI4-94 (rs2240340) and PADI4-104 (rs1748033) in 378 unrelated patients with RA (cases) and 204 healthy individuals (controls) of Chinese Han population. The major allele frequency of the five SNPs in case-control is 0.55 vs 0.56,0.55 vs 0.57,0.57 vs 0.62,0.54 vs 0.55,0.60 vs 0.60, respectively. The frequency sum of the two major haplotype (ACCCC, GTGTT) was accounded 76.8% in case and 81.5% in controls. There were no significant differences in the frequency of PADI4 alleles, genotypes and haplotypes between RA cases and controls. The results indicate that PADI4 polymorphisms do not play an important role in the development of AS in Chinese Han population.The polymorphism of PADI4 gene might differ in different populations. To a homogeneous multigene disorders like AS and RA, PADI4 only plays a little part in the course of disease and the polymorphism of PADI4 gene differ in different populations. At the same time, many genetic and environmental factors involved in AS or RA onset and development. In an attempt to elucidate the etiology of AS or RA, the further association studies involving more cases and different ethnic groups will be required. In the post-genome era, the Genome-wide association study (GWAS) is a powerful tool in discovering clues to AS and RA, and indicate some directions for association study. Our research results suggested that the PADI4 gene is not associzted with AS and RA in Chinese Han population. Its association to other autoimmunological diseases needs further investigation.更多还原