Analysis on the genetic polymorphisms and haplotypes of vitamin D receptor in three hundred and eighty-two patients with ulcerative colitis

Abstract

Objective To investigate the relationship between polymorphisms and haplotypes of vitamin D receptor (VDR) genes FokⅠ,BsmⅠ,ApaⅠ,TaqⅠ and ulcerative colitis (UC) in Han population of Zhejiang province.Methods From January 2004 to September 2012,382 patients with UC were collected and 489 age and gender matched healthy individuals were collected at the same period as controls.Two milliliter fasting peripheral blood of subjects was obtained for whole-genome DNA isolation.Microsequencing technology was applied.Polymnorphisms of VDR were determined through multiplex polymerase chain reaction (PCR) amplification,PCR products purification,extension,second purification and capillary electrophoresis genotype.Whether the distribution of VDR FokⅠ,BsmⅠ,ApaⅠ,Taq Ⅰ genotype of control group met Hardy-Weinberg equilibrium was analyzed by chi-square test.After age,gender and smoking factors adjusted,the differences of VDR FokⅠ,BsmⅠ,ApaⅠ,TaqⅠ allele and genotype frequencies between UC group and control group were analyzed by non-conditional Logistic regression analysis,and their effects on clinic-pathological features of patients with UC were also analyzed.Linkage disequilibrium and haplotype analysis was made by Haploview 4.2 software.Results The distributions of VDR FokⅠ,Bsm],ApaⅠ,TaqⅠ genotype met Hardy-Weinberg equilibrium (all P＞0.05).After age,gender and smoking factors adjusted,the results of non conditional Logistic regression analysis indicated that there were no significant differences in VDR FokⅠ,BsmⅠ,ApaⅠ,TaqⅠ allele and genotype frequencies between UC group and control group (all P＞0.05).However,the frequencies of mutant allele (C) and genotype (TC+CC) in VDR FokⅠ of patients with mild and moderate UC (54.14％,353/652 ; 81.60％,266/326) were significantly higher than those of patients with severe UC (39.29％,44/112; 57.14％,32/56; OR=1.825 and 3.322,95％CI 1.212 to 2.747 and 1.828 to 6.061,both P＜0.01).There was no correlation between VDR BsmⅠ,ApaⅠ,TaqⅠ and severity of UC (all P＞0.05).There were no significant differences in VDR FokⅠ,BsmⅠ,ApaⅠ,TaqⅠ allele and genotype frequencies between UC patients with distal colitis and extensive colitis (all P＞0.05).There were linkage disequilibrium in VDR BsmⅠ,ApaⅠ and TaqⅠ.Linkage disequilibrium coefficient (D') between BsmⅠ and ApaⅠ was 0.982 and the correlation coefficient (r2) was 0.156; D' between ApaⅠ and TaqⅠ was 0.929 and r2 was 0.141; D' between BsmⅠ and TaqⅠ was 0.826 and r2 was 0.675.Among eight haplotypes (GAC,ACC,GCC,AAT,ACT,GCT,GAT and AAC),the frequency of AAC haplotype of UC group (3.80％,29/764)was lower than that of control group (5.93％,58/978) and the difference was statistically significant (OR=0.631,95％CI 0.394-1.013,P=0.039).Conclusions The genetic mutation of VDR FokⅠ may influence severity of patients with UC.The risk of developing UC is low in the individuals carrying AAC haplotype of VDR BsmⅠ,ApaⅠ,TaqⅠ suffering UC. Key words: Colitis, ulcerative; Receptors, calcitriol; Gene polymorphism