【摘要】 目的　用连锁不平衡 (linkagedisequilibrium)的方法对 1号染色体狼疮易感区域进行进一步的精细定位 ,并由此定位新的系统性红斑狼疮 (SLE)候选基因。方法　用 9对高密度的微卫星标记对 1q2 3 2 4易感区域进行连锁不平衡分析 ;用延伸型传递不平衡试验 (ETDT)、GeneHunter和家系为基础的相关分析 (FBAT)软件分析连锁不平衡的结果 ;用TaqMan荧光实时定量聚合酶链反应(PCR)检测候选基因mRNA的表达量 ;用等位基因分型PCR对候选基因内的 4个SNP分型。结果　①发现微卫星标记D1S2 6 2 8(P =0 0 0 0 987,Pc=0 0 0 12 )和D1S2 6 73(P =0 0 0 70 82 ,Pc =0 0 104 )的等位基因存在整体的显著传递不平衡 ) ;②发现D1S2 6 2 8 119bp (Pc =0 0 0 12 ;传递∶不传递 =91∶4 5 ,P =0 0 0 0 1)和D1S2 6 73 10 3bp (Pc =0 0 10 4 ,传递∶不传递 =10 9∶6 7,P =0 0 0 16 )等位基因从杂合子父母优势传递给受累后代 ;③在中国汉族红斑狼疮核心家系中单倍型D1S2 6 2 8(119bp) D1S2 6 73(10 3bp) (传递∶不传递 =4 3∶18,P =0 0 0 14 )和单倍型D1S2 6 2 8(119bp) D1S2 6 73(10 7bp) (传递∶不传递 =2 9∶12 ,P =0 0 0 79)存在传递不平衡。在中国汉族SLE患者中PBX1的mRNA的表达量显著下降 (P <0 0 0 0 1)。PBX1基因更多还原

【Abstract】 Objective To identify candidate genes within the putative systemic lupus erythematosus (SLE) susceptibility locus at 1q23 24.Methods Evidence for linkage disequilibrium (LD) was assessed using extended transmission disequilibrium tests (ETDT),Gene Hunter,and family based association test (FBAT) programs.TaqMan real time quantitative PCR was used for detecting mRNA expression of a positional candidate gene.Four SNPs located within the candidate gene were genotyped by allelic discrimination PCR (AD PCR) using 5′ nuclease assay.Results The LD analysis showed:① overall skewing of the transmissions of D1S2628 ( Pc =0 001 2) and D1S2673 ( Pc =0 010 4) from heterozygous parents to affected offspring;② preferential transmission of one allele of D1S2628 and D1S2673 (t∶non t=91∶45, P =0 000 1;t∶non t=109∶67, P =0 001 6,respectively);and ③ preferential transmission of certain haplotypes of the two markers ( P =0 001 4 and 0 007 9 respectively for two haplotypes).A positional candidate gene PBX1 (pre B cell leukemia transcription factor 1) mapped within 0 3 Mb of D1S2628 was found to express at lower levels in Chinese SLE patients (mean ΔC T± s =5 70±0 18, n =129) compared to Chinese normal controls (mean ΔC T± s =1 64±0 36, n =72, P <0 000 1).Two SNP haplotypes (G C Cand G C C G) of PBX1 showed significant association with SLE susceptibility in an extending Chinese cohort of 361 families ( P =0 004 and 0 008 respectively) and in a Caucasian cohort of 233 families ( P =0 019 6 and 0 033 9 respectively).The same haplotypes containing SNP1 (G) SNP2 (C) SNP3(C) within PBX1 exhibit significant association with SLE susceptibility in both Chinese and Caucasian simplex families.In combined cohort,these two haplotypes showed preferential transmission (haplotype of G C C t∶non t=19∶2, P =0 000 2;haplotype of G C C G t∶non t=14∶1, P =0 000 8).Conclusion These data suggest the presence of a SLE susceptibility gene physically closes to markers DIS2628 and D1S2673 in a Chinese cohort.The lower expression of PBX1 and the significant association of PBX1 SNP haplotypes with SLE susceptibility suggest PBX1 might be a novel candidate susceptibility gene.更多还原