【作者】 张云；

【导师】 王姮； 肖新华； 李玉秀； 孙琦；

【作者基本信息】 中国协和医科大学 ， 内分泌与代谢学， 2009， 博士

【摘要】 研究背景1型糖尿病(type 1 diabetes,T1D)可以被看作是自身免疫对β细胞的选择性破坏与β细胞再生之间平衡被打破的结果。任何导致β细胞破坏(主要通过免疫机制)和影响β细胞发育及再生的因素都可能参与T1D的发生。PAX4(the paired boxgene 4)基因定位于人染色体7q32,编码一种胚胎时期胰腺β细胞发育的必需转录因子,在引导未分化细胞转化为胰岛素分泌细胞过程中发挥重要作用。国外有研究报道位于PAX4基因外显子9上的一个多态性位点,A1168C(rs712701),与T1D相关,但研究结果报道不一致。本文应用以人群为基础的病例一对照研究方法,以PAX4作为候选基因,在中国汉族人群中探讨其基因多态性与T1D遗传易感的关联性。研究方法随机选取无亲缘关系的中国汉族人458例,其中T1D患者134例,无糖尿病家族史、无糖尿病史且空腹血糖正常(<100mg/dL)的非糖尿病对照受试者324例。提取外周血白细胞基因组DNA,运用聚合酶链反应—限制性片断长度多态性技术(polymerase chain reaction-restriction fragment length polymorphism,PCR-RFLP)对PAX4基因单核苷酸多态性(single nucleotide polymorphism,SNP) rs712701,rs2233580,rs2233575进行基因分型,分析各SNP及其组成的单倍型与T1D遗传易感的相关性。应用SPSS 11.5软件包软件包分析数据。以双侧P<0.05为有统计学显著性。研究结果1.PAX4基因多态性位点rs712701,rs2233580,rs2233575的基因型频率在对照组和T1D患者中均符合Hardy—Weinberg平衡定律。随机病例—对照研究结果显示3个SNP的基因型分布和等位基因频率在T1D组和非糖尿病对照组间均无显著差别。2.SNP rs2233575,rs2233580,rs712701可组成四种常见的单倍型(频率≥3%):A-G-A,G-G-A,G-G-C和G-A-A。四种单倍型频率在T1D组和非糖尿病对照组间均无显著差别。3.非糖尿病对照组基因型与临床表型分析结果显示,SNP rs2233575位点GA+AA基因型携带者空腹胰岛素水平显著低于GG基因型携带者(5.7 vs 7.0μmol/L,P=0.048)。结论本研究首次在中国汉族人群中进行了有关PAX4基因多态性的研究。本组人群的研究结果未发现PAX4基因多态性与T1D的发生相关。位于PAX4基因启动子区的SNP rs2233575可能与空腹胰岛素水平相关。研究背景流行病学调查研究显示,低出生体重是成年期糖代谢异常(impaired glucosemetabolism,IGM)的独立危险因素。低出生体重与成年期IGM相关的分子机制目前仍不清楚。根据胎儿胰岛素假说,低出生体重与T2D具有相同遗传基础。参与调节胰岛素分泌及其作用的多基因遗传因素,可通过在宫内及成年后的作用,产生两种相关联的表型——低出生体重和成年期胰岛素抵抗及T2D的发生。因此,本研究拟在流行病学调查的基础上,研究T2D易感基因在出生体重与成年期IGM的相关中的作用,初步探讨中国汉族人低出生体重与IGM相关的遗传机制。这将是第一次在中国人群中进行的关于出生体重的遗传基础的研究。研究方法本研究以1181名1921-1954年间在北京协和医院出生的受试者为研究对象,选择T2D易感基因转录因子7类似物(transcription factor 7 like 2,TCF7L2)、锌转运蛋白-8(solute cartier family 30,member 8,SLC30A8)、电压门控性钾通道(potassiumvoltage-gated channel,KQT-like subfamily,member 1,KCNQ1)及泛酸激酶4(pantothenate kinase 4,PANK4)基因为候选基因,采用Taqman探针等位基因鉴别分析法进行基因分型,探讨基因与出生体重及成年期IGM的相关性。应用SPSS 11.5软件包分析数据。以双侧P<0.05为有统计学显著性。1校正年龄、性别和BMI的影响后,KCNQ1基因SNP rs2074196、rs2237895,TCF7L2基因SNP rs290487和PANK4基因SNP rs7535528与IGM相关。其中,rs2074196 TT基因型(P=0.016,OR=0.628,95%CI0.430-0.917)、rs2234895 AA基因型(P＝0.007,OR=0.706,95%CI 0.549-0.907)、rs290487 CT基因型(P=0.022,OR=0.752,95%CI0.590-0.960)和rs7535528 AA基因型(P=0.007,OR=0.574,95%CI0.384-0.858)分别是IGM发生的保护因素。基因型与临床表型分析结果显示,KCNQ1基因SNP rs2074196与FINS和HOMA-IS相关,GG基因型携带者空腹胰岛素(fasting insulin,FINS)和HOMA-IS均显著低于TT和TG基因型携带者(P值分别为0.043和0.004);TCF7L2基因SNP rs290487与HOMA-IR相关,CT基因型携带者HOMA-IR均显著低于CC和TT基因型携带者(P=0.046)。2线性回归分析结果显示,校正了性别、孕周、产次和母亲年龄等混杂因素的影响后,KCNQ1基因SNP rs2074196与出生体重相关(P=0.032),即每多携带一个糖尿病易感G等位基因,出生体重增加40g。3按出生体重分层后,在出生体重<3000g的受试者中,TCF7L2基因SNPrs11196218和SLC30A8基因SNP rs2466293与IGM发生相关;在出生体重≥3000g的受试者中,TCF7L2基因SNP rs290487,PANK4基因SNP rs7535528和KCNQ1基因SNP rs2074196、rs2237895与IGM发生相关。基因型和临床表型分析结果显示,按出生体重分层后,仅在出生体重≥3000g的受试者中,KCNQ1基因SNPrs2074196与HOMA-IS相关,GG基因型携带者HOMA-IS显著低于TT和TG基因型携带者(P=0.008)。TCF7L2基因SNP rs290487和PANK4基因SNP rs7535528与HOMA-IR相关:rs290487位点CT基因型携带者HOMA-IR显著低于CC和TT基因型携带者(P=0.044);rs7535528位点GG基因型携带者HOMA-IR显著低于GA和AA基因型携带者(P=0.032)。而出生体重<3000g受试者中未发现基因型与临床表型相关。1在本组人群中,KCNQ1基因SNP rs2074196、rs2237895,TCF7L2基因SNPrs290487和PANK4基因SNP rs7535528与IGM相关。基因型与临床表型分析结果显示,KCNQ1基因SNP rs2074196与胰岛素分泌指数相关;TCF7L2基因SNPrs290487与胰岛素抵抗指数相关。2本研究是第一项在中国人群中进行的关于出生体重的遗传学研究。研究结果显示KCNQ1基因SNP rs2074196与出生体重相关,每多携带一个糖尿病易感G等位基因与出生体重增加40g相关。3基因与出生体重在糖代谢异常发生中存在交互作用。更多还原

【Abstract】 BackgroundsType 1 diabetes(T1D) can be viewed as the result of an imbalance between autoimmune p cell destruction and p cell regeneration.So alterations in genes invovled in the autoimmune destruction or islet cell development and regeneration should play a role in the pathology of T1D.Pax4(the paired box 4),a member of the Pax family of homeodomain transcription factors,is essential to the differentiation and function ofβcells.Recently,Biasom-Lauber reported a dominant effect of a non-synonymous single nucleotide polymorphism(SNP) in PAX4(rs712701) on the T1D susceptibility in both Swiss and German populations,in which C allele was associated with susceptibility. However,this effect has not been found in studies by Hermann and Maier.In present study,we aimed to evaluate whether the paired box gene 4(PAX4) may play a role in the pathogenesis of type 1 diabetes(T1D) in Chinese Han population.MethodsOne hundred and thirty-four cases with T1D and 324 non-diabetic control subjects were selected randomly from Han Chinese.Three single nucleotide polymorphisms (SNPs) rs712701,rs2233580,rs2233575 were genotyped by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and analyzed their association with T1D.All statistical analyses were performed using the SPSS statistical package,version 11.5. A P value of less than 0.05 was considered statistically significant.Results1.Genotype distributions for all the SNPs studied were found to be consistent with HWE in non-diabetic controls.No difference was found in genotype or allele frequencies between patients and non-diabetic controls in all three SNPs.2.There were four common haplotypes with a frequency of at least 3%:A-G-A, G-G-A,G-G-C和G-A-A.All the haplotypes had similar frequencies in non-diabetic control subjects and T1D patients. 3.The association between genotypes and phenotypes in non-diabetic control subjects were analyzed.In SNP rs2233575,we found that the carriers with AA and GA genotypes had lower plasma insulin level than the subjects with GG genotype(5.7 vs 7.0μmol/L, P=0.048)ConclusionsThe present study identified that the PAX4 gene was not associated with the risk of T1D in a Han Chinese sample,suggesting that it may not influence T1D risk in this population.SNP rs2233575 in the promoter region of the PAX4 gene might be associated with fasting insulin level.This is the first study on the PAX4 gene in a Chinese population. BackgroundsNumerous epidemiological studies demonstrated a strong association between low birth weight and the later development of the impaired glucose metabolism.According to the fetal insulin hypothesis,low birth weight and type 2 diabetes(T2D) shared the same insulin-resistant genotype.Common polygenic genetic factors that increase insulin resistance would produce two phenotypes-a small,thin baby in utero and an adult with insulin resistance and increased risk of impaired glucose metabolism.The present study was to study the effect of diabetes-susceptibility genes on the association of low birth weight and impaired glucose metabolism(IGM).This would be the first genetic study of birth weight in Chinese.MethodsOne thousand,one hundred and eighty one subjects born in Peking Union Medical College Hospital from 1921 to 1954 were recruited.Four diabetes-susceptibility genes, TCF7L2(transcription factor 7 like 2),SLC30A8(solute carrier family 30,member 8), KCNQ1(potassium voltage-gated channel,KQT-like subfamily,member 1) and PANK4 (pantothenate kinase 4) were selected as candidates genes.Genotyping of the variants was performed using Taqman allelic discrimination assay.All statistical analyses were performed using the SPSS statistical package,version 11.5. A P value of less than 0.05 was considered statistically significant.Results1.Multiple variable logistic regression analyses with adjustment for age,sex and BMI, SNPrs2074196TT(P＝0.016,OR＝0.628,95%CI 0.430-0.917)、rs2234895AA(P＝0.007,OR＝0.706,95%CI 0.549-0.907)、rs290487 CT(P＝0.022,OR＝0.752, 95%CI 0.590-0.960) and rs7535528 AA(P＝0.007,OR＝0.574,95%CI 0.384-0.858) genotypes appeared protective effect on IGM.SNP rs2074196 in gene KCNQ1 was associated fasting insulin and HOMA-IS,carriers with GG genotype had significant lower fasting insulin(FINS) and HOMA-IS than those with TT and TG genotypes;SNP rs290487 in gene TCF7L2 was associated with HOMA-IR,the carriers with CT genotype had significant lowerHOMA-IR levels than those with other genotypes(P=0.046).2.SNP rs2074196 in gene KCNQ1 was associated with birth weight after adjustment for sex,gestational weeks,parity and maternal age,the per-risk allele effect size estimate of the association was 40g.3.Stratified by birth weight,the associations between IGM and SNPs rs290487 in gene TCF7L2,rs2074196,rs2237895 in gene KCNQ1,and rs7535528 in gene PANK4 were only found in subject whose birth weight larger than(or equal to) 3000g;the association between impaired glucose metabolism and SNP rs2466293 in gene SLC30A8 and rs11196218 in gene TCF7L2 were found to be associated with IGM in those whose birth weight smaller than 3000g.And in subject whose birth weight larger than(or equal to) 3000g,subjects with CC genotype in rs290487 had higher HOMA-IR than subjects with CT and TT;subjects with GG in rs2074196 had lower HOMA-IS than GT and TT.Conclusions1.Impaired glucose metabolism were associated with SNPs rs290487 in gene TCF7L2, rs7535528 in gene PANK4,and rs2074196,rs2237895 in gene KCNQ1;no association was found with SNPs rs11196218 in gene TCF7L2,rs1980789 in gene PANK4,and rs13266634,rs2466293 in gene SLC30A8.2.The was the first study about the role of genes in birth weight in Chinese.SNP rs2074196 in gene KCNQ1 was associated with birth weight after adjustment for sex, gestational weeks,parity and maternal age,the per-risk allele effect size estimate of the association was 40g.3.There were interactions between the effects of genes and birth weighton on impaired glucose metabolism.更多还原