摘要目的 探讨维生素D受体(VDR)基因多态性及血清25-羟维生素D[25(OH)D]水平与克罗恩病(CD)的关系.方法 在297例CD患者和446例对照者中,采用SNaPshot技术检测VDR基因4个位点(Fok Ⅰ、Bsm Ⅰ、Apa Ⅰ、Taq Ⅰ)单核苷酸多态性.从中随机选取124例CD患者和188例年龄、性别相匹配的同期对照者,采用电化学发光法检测血清25(OH)D水平.结果 经x2检验和Bonferroni校正后,CD组中Bsm Ⅰ位点的突变等位基因(A)和基因型(GA+ AA)频率显著低于对照组[3.70％ (22/594)比7.51％(67/892),95％ CI0.289 ～0.776,P=0.002;7.41％ (22/297)比14.80％ (66/446),95％ CI0.277 ～0.765,P=0.002];Taq Ⅰ位点的突变等位基因(C)及基因型(TC+ CC)频率亦显著低于对照组[4.21％ (25/594)比7.62％(68/892),95％ CI0.333 ～0.852,P=0.008;8.42％(25/297)比14.57％(65/446),95％ CI0.331 ～0.877,P=0.012].采用Haploview4.2和R语言软件包进行连锁不平衡和单倍型分析,结果显示Bsm Ⅰ、Apa Ⅰ和Taq Ⅰ位点紧密连锁,CD组中AAC单倍型频率显著低于对照组[3.14％比6.46％,95％ CI0.273 ～0.815,P=0.004].血清学分析发现CD组中25 (OH)D平均水平低于对照组[(15.46 ±8.11) μg/L比(21.64 ±9.45)μg/L,P＜0.001].线性回归分析提示CD患者中25 (OH)D平均水平与CD疾病活动指数(β=-0.829,P＜0.001)、血小板计数(β=-0.253,P＜0.001)和中性粒细胞百分比(β=-0.136,P =0.005)呈独立负相关,而与ESR(β=0.191,P=0.001)呈独立正相关.logistic回归构建基因-环境交互模型,结果显示25(OH)D缺乏(＜20 μg/L)和Apa Ⅰ位点突变基因型(CA+ AA)是CD的独立危险因素(OR=7.580,95％ CI2.983～19.261,P＜0.001;OR =2.842,95％ CI1.300～6.211,P =0.009);25(OH)D缺乏分别与Fok Ⅰ位点突变基因型(TC+ CC)、Apa Ⅰ位点突变基因型(CA+AA)及Taq Ⅰ位点突变基因型(TC+ CC)存在交互作用(OR =0.419,95％ CI0.194 ～0.906,P=0.027;OR=0.309,95％CI0.111 ～0.855,P=0.024;OR=5.841,95％CI 1.082 ～31.538,P=0.040).结论 VDR(Bsm Ⅰ、Apa Ⅰ、Taq Ⅰ)基因多态性及25(OH)D水平与CD密切相关;Apa Ⅰ位点突变基因型(CA +AA)和25(OH)D缺乏是CD的独立危险因素;VDR(Fok Ⅰ、Apa Ⅰ、Taq Ⅰ)基因突变与25(OH)D缺乏可能对CD的易感性产生协同影响.

abstractsObjective To investigate the association of Crohn's disease (CD) with vitamin D receptor (VDR) gene polymorphisms and serum 25-hydroxyvitamin D [25 (OH)D] level.Methods A total of 297 CD patients and 446 healthy controls were enrolled in our study.Four single nucleosides of VDR (Fok Ⅰ,Bsm Ⅰ,Apa Ⅰ and Taq Ⅰ) were genotyped by SNaPshot.Serum 25 (OH) D levels were tested by electro-chemiluminescence immunoassay in 124 CD patients and 188 matched random controls.Results By Chi-square test and Bonferroni correction,the frequencies of mutant allele (A) and mutant genotype (GA +AA) of Bsm Ⅰ were significantly decreased in CD patients compared to controls [3.70％ (22/594) vs 7.51％ (67/892),95 ％ CI 0.289-0.776,P =0.002;7.41％ (22/297) vs 14.80％ (66/446),95 ％ CI 0.277-0.765,P =0.002,respectively].The similar results were seen for the mutant allele (C) and mutant genotype (TC + CC) of Taq Ⅰ [4.21％ (25/594) vs 7.62％ (68/892),95％ CI 0.333-0.852,P =0.008;8.42％ (25/297) vs 14.57％ (65/446),95 ％ CI 0.331-0.877,P =0.012].The analyses of linkage disequilibrium (LD) and haplotype were performed by Haploview 4.2 and R software,respectively.The Bsm Ⅰ,Apa Ⅰ and Taq Ⅰ polymorphic loci were found to be in a strong LD,and the AAC haplotype was significantly reduced in CD patients compared to controls [3.14％ vs 6.46％,95％ CI 0.273-0.815,P =0.004].The further serological analysis showed that average serum 25 (OH)D level in CD patients was significantly lower than that of controls [(15.46 ±8.11) μg/L vs (21.64 ±9.45) μg/L,P ＜0.001].By linear regression analysis,serum 25 (OH)D levels in CD patients were negatively correlated to Crohn's disease activity index (β =-0.829,P ＜ 0.001),platelet count (β =-0.253,P ＜ 0.001) and the ratio of neutrophils (β =-0.136,P =0.005) independently,whereas positively related to erythrocyte sedimentation rate (β =0.191,P =0.001).Furthermore,logistic regression analysis was applied for establishing the models of gene-environment interaction.In result,both the mutant genotype (CA + AA) of Apa Ⅰ and vitamin D deficiency (＜20 μg/L) were shown to be the independent risk factors for CD (OR =7.580,95％ CI 2.983-19.261,P ＜ 0.001;OR =2.842,95％ CI 1.300-6.211,P =0.009,respectively).Besides,vitamin D deficiency in CD patients had multiplicative interactions with the mutant genotype (TC + CC) of Fok Ⅰ,genotype (CA + AA) of Apa Ⅰ and genotype (TC + CC) of Taq Ⅰ,respectively (OR =0.419,95％ CI 0.194-0.906,P =0.027;OR =0.309,95％ CI 0.111-0.855,P =0.024;OR=5.841,95％CI 1.082-31.538,P=0.040;respectively).Conclusions VDR (Bsm Ⅰ,Apa Ⅰ and Taq Ⅰ) polymorphisms and serum 25 (OH) D levels are significantly related to CD.Both the mutant genotype (CA + AA) of Apa Ⅰ and vitamin D deficiency are independent risk factors of CD.The mutations of VDR(Fok Ⅰ,Apa Ⅰ and Taq Ⅰ) and vitamin D deficiency might have a synergistic effect on CD susceptibility.