MDR1 polymorphisms and response to azathioprine therapy in patients with Crohn's disease

BACKGROUND: To investigate the contribution of multidrug resistance 1 (MDR1) gene pharmacogenetics (G2677T/A and C3435T) to the efficacy of azathioprine in inducing remission in patients with Crohn's disease (CD). METHODS: A cohort of 327 unrelated Spanish patients with CD recruited from a single center was studied. All patients were rigorously followed up for at least 2 years (mean time, 11.5 years). A case-control analysis of MDR1 G2677T/A and C3435T SNPs and 2 loci haplotypes in 112 steroid-dependent CD patients treated with azathioprine was performed. Patients were classified on the basis of response to azathioprine. RESULTS: A total 76 patients treated with azathioprine for longer than 3 months were included. Remission was achieved in 42 CD patients (55.3%). A higher frequency of the 2677TT genotype was found in nonresponders than in responders (17.65% versus 7.14%; OR = 2.8; 95% CI; 0.6-12.1; P = 0.11). Nonresponders to azathioprine were found to have a higher frequency of the 3435TT genotype than did CD patients who had achieved clinical remission (17.64% versus 4.76%; OR = 4.3; 95% CI, 0.8-22.8; P = 0.06). The 2677T/3435T haplotype was also more abundant in nonresponders (29.4% versus 20.2%), whereas the 2677G/3435C haplotype was more frequent in responders (58.3% versus 47.1%). Lack of response to azathioprine therapy in CD patients was 1.8-fold greater in carriers of the 2677T/3435T haplotype than in carriers of the 2677G/3435C haplotype (OR = 1.8; 95% CI, 0.82-3.9; P = 0.14). CONCLUSIONS: The results of our study indicate higher frequencies of the 2677TT and 3435TT genotypes and the 2677T/3435T haplotype in CD patients who did not respond to azathioprine. Additional replications in independent populations would confirm the real impact of these polymorphisms in response to azathioprine therapy.     

MDR1 gene: susceptibility in Spanish Crohn's disease and ulcerative colitis patients

BACKGROUND: The multidrug resistance MDR1 gene codes for a membrane transporter associated with inflammatory bowel disease. The polymorphism Ala893Ser/Thr (G2677T/A) previously showed significant association with Crohn's disease (CD) and the Ile1145Ile (C3435T) with ulcerative colitis (UC). We studied the association of both polymorphisms in an independent population to reveal the impact of the MDR1 gene on predisposition to inflammatory bowel disease. METHODS: Case-control study with 321 CD and 330 UC white Spanish patients recruited from the same center, and 352 healthy ethnically matched controls. RESULTS: A significant association of MDR1 C3435T with CD was observed (CC vs (CT + TT): P = 0.007; OR [95% CI] = 1.58 [1.12-2.23]). A CD susceptibility haplotype 2677T/C3435 was identified. No difference between UC patients as a whole and controls could be detected. CONCLUSIONS: New evidence supports the role of the MDR1 gene on CD susceptibility. Therefore, considering our results and those from others, the MDR1 gene behaves as a common risk factor for both CD and UC. We discovered that the C3435 allele conferring susceptibility to CD is different from the described 3435T UC risk allele.     

Associations of allelic variants of the multidrug resistance gene (ABCB1 or MDR1) and inflammatory bowel disease and their effects on disease behavior: a case-control and meta-analysis study

BACKGROUND: Allelic variants of the ATP-binding cassette, subfamily B member 1 (ABCB1), also known as the multidrug resistance gene (MDR1) that encodes the membrane-bound efflux transporter P-glycoprotein 170 (PGP-170), have been associated with inflammatory bowel disease but with conflicting results. METHODS: The present study examined the association of ABCB1 C3435T and G2677T/A in a large British case-control cohort of 828 Crohn's disease, 580 ulcerative colitis (UC) cases, and 285 healthy controls. The effect of these variants was further examined with respect to phenotypic and epidemiological characteristics. A meta-analysis was carried out of our results and those from 8 previously published association studies of the C3435T variant in inflammatory bowel disease. RESULTS: The 2677T allele was significantly increased in British UC cases compared with controls (45.2% vs. 39.6%; P = 0.034). In particular, the TT genotype was significantly associated with severe UC (odds ratio [OR] 1.90; 95% CI 1.01-3.55) and the use of steroids in UC (OR 1.77; 95% CI 1.08-2.88). No significant association was seen with C3435T and UC, Crohn's disease, or any clinical subgroup. A meta-analysis of 9 association studies of C3435T showed a significant association of the 3435T allele with UC (OR 1.12; 95% CI 1.02-1.23; P = 0.013) but not with CD. CONCLUSIONS: These results indicate that ABCB1 sequence variants are associated with a small increase in the risk of developing UC and may influence disease behavior.     

Multidrug resistance 1 gene polymorphism and susceptibility to inflammatory bowel disease

BACKGROUND: Several studies have evaluated the role of the multidrug resistance 1 gene (MDR1) polymorphism, which encodes the membrane-bound efflux transporter P-glycoprotein 170, in determining susceptibility to and disease behavior in inflammatory bowel disease (IBD), but with conflicting results. METHODS: A total of 211 patients with Crohn's disease (CD), 97 patients with ulcerative colitis (UC), and 212 control subjects were investigated for the presence of MDR1 G2677T/A and C3435T polymorphisms. Genotype frequencies of CD and UC patients were compared to those observed in a control population. Genotype-phenotype correlations with major clinical features were also established and estimated risks (odds ratio [OR] with 95% confidence interval [CI]) for the mutations were calculated by a logistic regression analysis and multiple correspondent analysis. RESULTS: No significant difference was observed for genotype frequencies for both MDR1 G2677T/A and C3435T polymorphisms on overall disease susceptibility for either CD or UC patients compared with control subjects. A significant association was found between the MDR1 C3435T polymorphism and patients with ileo-colonic CD (OR = 3.34; 95% CI: 1.34-8.27). Interestingly, a negative association was found between MDR1 C3435T polymorphism in patients with a positive family history for IBD (OR = 0.44; 95% CI: 0.20-0.95) and articular manifestations (OR = 0.29; 95% CI: 0.13-0.68). Both susceptible and protective effects were identified. No significant association between G2677T/A polymorphism and any specific subphenotypes was found, nor was there any association with subphenotypic categories of UC and both single nucleotide polymorphisms. CONCLUSIONS: The results of our study suggest that MDR1 gene polymorphism could have a role in determining susceptibility to IBD. The variability of this possible effect in the several studies reported so far may be the indirect expression of the complex role played by the MDR1 gene and its product, P-glycoprotein 170, in the regulation of host-bacteria interactions and in the pathogenesis of IBD.     

Multidrug resistance gene-1 polymorphisms and resistance to cyclosporine A in patients with steroid resistant ulcerative colitis

BACKGROUND: Cyclosporine A (CsA) is inconstantly effective in inducing remission in acute attacks of ulcerative colitis (UC) not responding to steroids. This study aimed to establish whether multidrug resistance gene (MDR)1 polymorphisms would be associated with CsA failure. PATIENTS AND METHODS: The distribution of the different genotypes of single nucleotide polymorphisms (SNP) G2677T/A and C3435T of MDR1 exons 21 and 26, respectively, was studied in 154 patients (mean age, 44 yr) who had received CsA to treat severe attacks of steroid resistant UC in 11 centers in France and Belgium. Patients were classified as CsA failure (n = 50) when they needed colectomy within 30 days after CsA initiation. The SNPs were detected by use of a 5' nuclease allelic discrimination assay. RESULTS: There was a significant association between the G2677T/A polymorphism distribution (exon 21) and the risk for CsA failure (P = 0.0001). The TT genotype of exon 21 was significantly associated with the risk compared with the two other genotypes (odds ratio, 3.77; 95% confidence interval, 1.42-9.97, P = 0.007). There was no significant association between the genotype C3435T distribution (exon 26) and the risk of CsA failure (P = 0.23). CONCLUSION: The TT genotype of exon 21 MDR1 polymorphisms is associated with a higher risk of CsA failure in patients with steroid resistant UC. Further studies should be performed to establish whether other treatments could be more efficient to avoid surgery in this subset of patients.     

ATP-binding cassette transporter ABCG2 (BCRP) and ABCB1 (MDR1) variants are not associated with disease susceptibility, disease phenotype response to medical therapy or need for surgeryin Hungarian patients with inflammatory bowel diseases

OBJECTIVE: MDR1 (ABCB1), a member of the ATP-binding cassette (ABC) transporters, is an attractive candidate gene for the pathogenesis of inflammatory bowel diseases (IBD) and perhaps for response to therapy. Since limited data are available on MDR1 and ABCG2 polymorphisms in East European IBD patients, the aim of this study was to investigate ABCG2 and MDR1 variants and responses to medical therapy and/or disease phenotype in Hungarian patients. MATERIAL AND METHODS: A total of 414 unrelated IBD patients (Crohn's disease (CD): 265, age: 35.2+/-12.1 years, duration: 8.7+/-7.6 years and ulcerative colitis (UC): 149, age: 44.4+/-15.4 years, duration: 10.7+/-8.9 years) and 149 healthy subjects were investigated. ABCG2 G34A, C421A and MDR1 C3435T, G2677T/A single nucleotide polymorphisms (SNPs) were detected using real-time polymerase chain reaction (PCR). Detailed clinical phenotypes were determined by reviewing the medical charts. RESULTS: The frequency of the ABCG2 and MDR1 SNPs was not significantly different among IBD, CD, UC patients and controls. There was no difference in risk for steroid resistance in CD patients carrying variant ABCG2 (19.6% versus non-carriers 18.4%, p=NS) or MDR1 3435T (CC: 22.2% versus CT/TT: 17.6%) alleles. In addition, carriage of the variant allele was not associated with disease phenotype, presence of extra-intestinal manifestations, smoking, response to infliximab therapy or the need for surgery. In UC, the carriage of variant ABCG2 alleles seemed to be preventive for arthritis (15.5% versus 31.7%, OR: 0.39, 95% CI: 0.16-0.98). CONCLUSIONS: MDR1 and ABCG2 SNPs were not associated with disease susceptibility or disease phenotype in Hungarian patients, and variant alleles did not predict the response to medical therapy or the need for surgery. Further studies are needed to clarify the association between the presence of ABCG2 variants and arthritis in UC.     

CTLA-4 and MDR1 polymorphisms increase the risk for ulcerative colitis:A meta-analysis

AIM:To evaluate the correlations between cytotoxic T lymphocyte-associated antigen-4(CTLA-4) and multidrug resistance 1(MDR1) genes polymorphisms with ulcerative colitis(UC) risk.METHODS:Pub Med,EMBASE,Web of Science,Cochrane Library,CBM databases,Springerlink,Wiley,EBSCO,Ovid,Wanfang database,VIP database,China National Knowledge Infrastructure,and Weipu Journal databases were exhaustively searched using combinations of keywords relating to CTLA-4,MDR1 and UC. The published studies were filtered using our stringent inclusion and exclusion criteria,the quality assessment for each eligible study was conducted using Critical Appraisal Skill Program and the resultant high-quality data from final selected studies were analyzed using Comprehensive Meta-analysis 2.0(CMA 2.0) software. The correlations between SNPs of CTLA-4 gene,MDR1 gene and the risk of UC were evaluated by OR at 95%CI. Z test was carried out to evaluate the significance of overall effect values. Cochran's Q-statistic and I2 tests were applied to quantify heterogeneity among studies. Funnel plots,classic fail-safe N and Egger's linear regression test were inspected for indication of publication bias.RESULTS:A total of 107 studies were initially retrieved and 12 studies were eventually selected for metaanalysis. These 12 case-control studies involved 1860 UC patients and 2663 healthy controls. Our major result revealed that single nucleotide polymorphisms(SNPs) of CTLA-4 gene rs3087243 G A and rs231775 G A may increase the risk of UC(rs3087243 G A:allele model:OR = 1.365,95%CI:1.023-1.822,P = 0.035; dominant model:OR = 1.569,95%CI:1.269-1.940,P 0.001; rs231775 G A:allele model:OR = 1.583,95%CI:= 1.306-1.918,P 0.001; dominant model:OR = 1.805,95%CI:1.393-2.340,P 0.001). In addition,based on our result,SNPs of MDR1 gene rs1045642 C T might also confer a significant increases for the risk of UC(allele model:OR = 1.389,95%CI:1.214-1.590,P 0.001; dominant model:OR = 1.518,95%CI:1.222-1.886,P 0.001).CONCLUSION:CTLA-4 gene rs3087243 G A and rs231775 G A,and MDR1 gene rs1045642 C T might confer an increase for UC risk.     

The association between multidrug resistance-1 gene polymorphisms and outcomes of allogeneic HLA-identical stem cell transplantation

The impact of single nucleotide polymorphisms of two loci (C3435T and G2677T/A) of the multidrug resistance-1 gene (MDR1) was investigated in 82 patients undergoing allogeneic stem cell transplantation (SCT). The GG genotype on G2677T/A loci was associated with higher non-relapse mortality than was the non-GG genotype (67% vs. 32%, p=0.0073), but not the C3435T (p=0.2026) or MDR1 haplotype (p=0.2238). Accordingly, overall survival was significantly correlated with the G2677T/A genotype (p=0.0048). Multivariate analysis also showed that the GG genotype at G2677T/A had an unfavorable prognosis in terms of overall survival (p=0.003) and non-relapse mortality (p=0.031). In conclusion, the G2677T/A genotype seems to be associated with transplantation outcomes, especially non-relapse mortality.     

Multi-drug resistance 1 polymorphism is associated with reduced risk of gastric cancer in the Japanese population

BACKGROUND AND AIMS: Host genetic factors play a key role in gastric carcinogenesis, but the mechanism has not been clarified. The multi-drug resistance 1 (MDR1) gene mediates the expression of P-glycoprotein, which has a role in active transport of various substrates, including xenobiotics, and thus has a protective function in various tissues and organs like gastrointestinal epithelial cells. C3435T polymorphism in exon 26 of the MDR1 gene influences P-glycoprotein expression and activity in the gastrointestinal tract. We investigated the influences of MDR1 gene polymorphism on the risk of gastric cancer. METHOD: The study was performed on 157 patients with gastric cancer (GC) and 104 patients without GC as the control group. C3435T polymorphism of MDR1 was investigated by PCR-RFLP in all of the patients. RESULTS: The MDR1 3435 TT genotype showed a significantly higher frequency in controls than in GC patients (OR = 0.43; 95% CI = 0.23-0.79). There were no significant differences of the CT and CC genotype frequencies between GC patients and controls. We also found that the 3435TT genotype of MDR1 was associated with a lower risk of non-cardiac cancer (OR = 0.42; 95% CI = 0.23-0.79), middle-third cancer (OR = 0.36; 95% CI = 0.17-0.77), advanced cancer (OR = 0.31; 95% CI = 0.13-0.73), venous invasion (OR = 0.30; 95% CI = 0.10-0.91), and lymph node metastasis (OR = 0.28; 95% CI = 0.13-0.65). CONCLUSION: Our data suggest that 3435T/T polymorphism of MDR1 is associated with a reduced risk of gastric cancer in the Japanese population.     

Cyclooxygenase-2, multidrug resistance 1, and breast cancer resistance protein gene polymorphisms and inflammatory bowel disease in the Danish population

Objective. Crohn's disease (CD) and ulcerative colitis (UC) are characterized by an impaired mucosal defence to normal constituents of the intestinal flora and a dysregulated inflammatory response. The purpose of the study was to investigate whether single nucleotide polymorphisms (SNPs) in genes involved in these processes were associated with CD and UC. Material and methods. Allele frequencies of the cyclooxygenase 2 (COX-2/PTGS2/PGHS2) G-765C and breast cancer resistance protein (BCRP/ABCG2) C421A as well as allele and haplotype frequencies of multidrug resistance 1 (MDR1, ABCB1) SNPs G2677T/A, C3435T and G-rs3789243-A (intron 3) were assessed in a Danish case-control study comprising 373 CD and 541 UC patients and 796 healthy controls. Results. Carriers of the homozygous COX-2 and MDR1 intron 3 variant had a relatively high risk of CD, odds ratio (95% CI) (OR (95% CI))=2.86 ((1.34–5.88) p=0.006) and 1.39 ((0.99–1.92) p=0.054), respectively, and for UC of 2.63 ((1.33–5.26) p=0.005) and 1.28 ((0.96–1.51) p=0.093), respectively, assuming complete dominance. No association was found for BCRP or other MDR1 SNPs, or for selected MDR1 haplotypes. No effect-modification of smoking habit at the time of diagnosis was found. Conclusions. An effect of the COX-2 polymorphism on both CD and UC was shown which is compatible with the presence of a recessive allele in linkage equilibrium with the SNP marker in the COX-2 gene. The polymorphism located in intron 3 of the MDR1 gene showed a weak association with CD, and a marginally suggestive association with UC.     

The pregnane X receptor locus is associated with susceptibility to inflammatory bowel disease

BACKGROUND & AIMS: The pregnane X receptor (PXR) regulates an array of genes involved in the response to xenobiotics. Evidence from several studies suggests that xenobiotic metabolism may play a role in inflammatory bowel disease (IBD) and that low levels of PXR may be associated with disease expression. The aim of this study was to investigate the association of functional polymorphisms of the PXR encoding gene (NR1I2) with disease in IBD populations. METHODS: This was a case-control study examining 8 NR1I2 single nucleotide polymorphisms (SNPs) previously associated with altered activity of PXR-regulated genes in an Irish cohort including 422 patients with IBD and 350 ethnically matched controls. RESULTS: We showed significant associations of NR1I2 with IBD, Crohn's disease (CD), and ulcerative colitis (UC) groups compared with a control population for SNPs -23585 (IBD: P = .000008; odds ratio [OR], 1.62; 95% confidence interval [CI], 1.31-2.00) and -24381 (IBD: P = .0002; OR, 1.50; 95% CI, 1.21-1.84). SNPs 7635 (P = .0008) and 8055 (P = .007) were found to be associated with IBD and CD but not UC. Risk of IBD is strongly correlated to genotype at these sites, especially for the -25385CC genotype (P = .00001; OR, 2.92; 95% CI, 1.87-4.66). We also show specific correlations of IBD phenotype with genotypes and haplotypes in the patient group. CONCLUSIONS: These results show that genetic variation in the PXR encoding gene, which has been associated with altered activity of PXR, is strongly associated with susceptibility to IBD, CD, and UC.     

溃疡性结肠炎患者中肿瘤坏死因子相关凋亡诱导配体基因多态性及单倍型分析

目的 探讨肿瘤坏死因子相关凋亡诱导配体(Trail)基因多态性及单倍型与溃疡性结肠炎(UC)的关系.方法 收集UC患者331例,健康对照者832名,PCR扩增Trail目的基因后,直接测序检测Trail基因3非编码区(G1525A/G1588A/C1595T)三种单核苷酸多态性,并分析Trail单倍型与UC的关系.结果 与对照组相比较,Trail G1525A突变等位基因A和基因型GA+ AA的频率在UC组中明显降低(P值均＜0.01);UC组Trail G1588A和C1595T两位点突变等位基因A和T的频率明显低于对照组,且差异有统计学意义(P值均＜0.01).轻和中度UC患者Trail C1595T突变等位基因T和CT+ TT基因型频率为49.15％和64.51％,重度UC患者分别为72.37％和84.21％,两组比较差异均有统计学意义(OR值分别=2.710和2.935,95％CI:1.598～4.596和1.188～7.249,P值均＜0.05).重度UC患者Trail G1525A突变等位基因A的频率为48.69％,较轻和中度UC患者(35.16％)增加(OR=1.750,95％CI:1.082～2.830,P=0.021).UC组中AAT单倍型频率显著低于对照组(43.09％比58.41％,95％CI:1.549～2.229,P＜0.01);GAT单倍型频率在UC组中明显增高(10.15％比0.18％,95％CI:0.005～0.051,P＜0.01).结论 Trail基因多态性及单倍型与UC易感性密切相关.     

细胞毒T淋巴细胞相关抗原4基因多态性与汉族溃疡性结肠炎患者的相关性研究

目的　研究细胞毒T淋巴细胞相关抗原4(CTLA- 4)基因外显子1的49位点A/G和启动子- 318位点C/T多态性与溃疡性结肠炎(UC)的相关性。方法　采用序列特异性引物聚合酶链反应(PCR -SSP)方法,检测82例中国湖北汉族溃疡性结肠炎患者(UC)以及204 例健康对照者CTLA- 4 基因外显子1的49位点A/G和启动子-318位点C/T的基因型和单倍型。结果　UC患者CTLA -4 A+49G和C- 318T基因型与正常对照组间差异无统计学意义(P>0.05),且与性别无关。在单倍型分析中,UC患者CTLA -4单倍型2,3(C-318 G49/T-318 A49)显著低于正常人群(26%比41%,P<0.05,OR=0.4918,95%CI:0.2784~0.8688)。结论　UC患者CTLA- 4 基因A+49G和C -318T单倍型2,3 与UC呈负相关。     

鼻咽癌放射敏感性与MDR1基因多态性的相关性

目的探讨鼻咽癌放射敏感性差异与多药耐药基因（MDRI）多态性的相关性。方法选择48例行根治性放疗的鼻咽癌患者,根据放疗疗效分为抵抗组和敏感组,针对MDR1基因多态性（21外显子G2677T和26外显子C3435T）行PCR扩增、基因测序分型及构建G2677T—C3435T单体型。结果G2677T TT基因型放射敏感性显著低于GG和GT基因型（P=0．017）,C3435T TT基因型放射敏感性显著低于CC和CT基因型（P=0．022）,携带2677T-3435T单体型的患者放射敏感性显著低于其他单体型携带者（P=0．013）。结论MDR1 G2677T和C3435T多态性可能提示鼻咽癌根治性放疗的疗效。     

Single-nucleotide polymorphism analysis of the multidrug resistance protein 3 gene for the detection of clinical progression in Japanese patients with primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a multifactorial disease in which genetic factors rather than environmental factors may predominantly contribute to the pathogenesis. In order to identify the genetic determinants of the disease severity and progression of PBC, we examined an association of seven tag single-nucleotide polymorphisms (SNPs) in the multidrug resistance protein 3 (MDR3/ABCB4) gene in 148 Japanese PBC patients and 150 age- and sex-matched healthy control subjects. SNPs were detected via polymerase chain reaction (PCR) restriction fragment length polymorphism and PCR direct DNA sequencing methods. Subsequently, haplotypes were constructed from three tag SNPs (rs31658, rs31672, and rs1149222) that were significantly associated with progression of PBC. Logistic regression analyses revealed that a Hap 2 haplotype and its homozygous diplotype, Hap 2/Hap 2, in MDR3 were closely associated with the susceptibility to jaundice-type progression of PBC [P = 0.004, odds ratio (OR) 3.93, 95% confidence interval (CI) 1.56-9.90 and P = 0.0003, OR 17.73, 95% CI 3.77-83.42, respectively]. Conversely, another haplotype, Hap 1, and its homozygous diplotype, Hap 1/Hap 1, were associated with the insusceptibility to the progression to late-stage PBC (P = 0.021, OR 0.55, 95% CI 0.33-0.91 and P = 0.011, OR 0.24, 95% CI 0.08-0.71, respectively). CONCLUSION: The present study is the first report of an association of MDR3 haplotypes and diplotypes with progression of PBC. The Hap 2/Hap 2 diplotype in MDR3 could therefore be potentially applied to DNA-based diagnosis in Japanese patients with PBC as a strong genetic biomarker for predicting the progression and prognosis of PBC.     

MICB 0106等位基因与湖北汉族人溃疡性结肠炎的相关性

目的 MHC Ⅰ类相关基因(MHC class Ⅰ chain-related gene,MIC)与MHC Ⅰ类基因连锁,同源性很高.我们的前期研究发现MICA和MICB微卫星多态性与溃疡性结肠炎(UC)相关,本研究继续探讨MICB第2、3、4外显子基因多态性与UC的相关性,以期发现UC的易感基因.方法 采用聚合酶链反应-单链构象多态性方法(PCR-SSCP),对105例湖北汉族UC患者和213例正常对照者进行MICB基因分型.结果 UC患者的MICB 0106等位基因频率较正常组显著增高(19.0%比8.9%,P=0.000,Pc＜0.001,OR=2.402,95%CI为1.488～3.879).在临床亚型分析中,MICB 0106等位基因频率在全结肠炎、中重度UC组及有肠外表现的UC患者中均显著增高(分别为24.4%比8.9%,P=0.000,Pc＜0.001,OR=3.294,95%CI为1.800～6.027;24.1%比8.9%,P=0.000,Pc＜0.001,OR=3.249,95%CI为1.893～5.576;20.5%比8.9%,P=0.002,Pc=0.012,OR=2.626,95%CI为1.418～4.861).而且MICB 0106等位基因频率在男性和年龄≥40岁的患者中比正常组显著增高(分别为22.1%比8.0%,P=0.001,Pc=0.006,OR=3.276,95%CI为1.737～6.178;28.8%比8.3%,P=0.000,Pc＜0.001,OR=4.500,95%CI为2.381～8.504).结论 MICB 0106等位基因与湖北汉族人UC存在显著相关性,而且与全结肠炎、中重度UC、肠外表现、男性及年龄≥40岁的患者有关,提示携带MICB 0106等位基因的个体对UC存在遗传易感性.     

Association of polymorphisms and haplotypes in the human growth hormone 1 (GH1) gene with breast cancer

The growth hormone 1 (GH1)/insulin-like growth factor I (IGF-I) axis plays an important role in the development of breast cancer. By binding to its receptor, GH1 stimulates the production of IGF-I and its binding protein IGFBP3, resulting in the regulation of cell proliferation, differentiation and apoptosis. The GH1 gene expression is regulated by a highly polymorphic proximal promoter and a distal locus control region (LCR) 14.5 kb upstream of the gene. We investigated the effect of single nucleotide polymorphisms (SNPs) in the LCR and in the promoter region and an intron 4 SNP (IVS4+90 T/A) on breast cancer risk in a large cohort of Polish and German familial breast cancer cases and controls. SNPs in the LCR did not show an influence on breast cancer risk, either alone or in haplotypes. Three SNPs in the promoter region (G-340T, A-68G/C and A-63T/C) showed an increased and four SNPs (A-137G, G-119T, G-93delG and T-4G) a decreased allele frequency in the cases compared with the controls. Two of the SNPs (A-137G and G-93delG) lead to a decreased breast cancer risk among the minor allele carriers in the joint analysis of the two populations (odds ratio (OR) 0.62, 95% confidence interval (95% CI) 0.44-0.89, P = 0.01 and OR 0.65, 95% CI 0.47-0.90, P = 0.01, respectively). Haplotype analysis with these seven promoter SNPs revealed a protective association (OR 0.61, 95% CI 0.37-1.00, P = 0.04) for the haplotype GAGdAAT, containing the G-93delG variant allele, which in the single analysis already showed a protective effect. The effect was marginally stronger in combination with the LCR GC haplotype (OR 0.49, 95% CI 0.23-1.01, P = 0.04).     

MDR1 gene C3435T polymorphism and cancer risk: a meta-analysis of 34 case–control studies

Background

P-glycoprotein, the product of the MDR1 gene, is a transmembrane active efflux pump for a variety of environmental toxins and xenobiotics. Epidemiological studies have evaluated the association between MDR1 C3435T polymorphism and cancer susceptibility. However, published data are still inconclusive.

Methods

To derive a more precise assessment of this relevance, we performed a meta-analysis, up to September 2010, of 5,196 cases with different cancer types and 6,827 controls from 34 published case–control studies. Summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for MDR1 C3435T polymorphism and cancer were estimated using fixed- and random-effects models when appropriate.

Results

The overall results suggested that the variant was associated with a moderately increased cancer risk in all comparison models tested (OR?=?1.26, 95% CI: 1.06–1.50 for TT vs. CC; OR?=?1.19, 95% CI: 1.04–1.37 for CT vs. CC; OR?=?1.15, 95% CI: 1.01–1.32 for recessive model; OR?=?1.21, 95% CI: 1.06–1.38 for domain model, and OR?=?1.14, 95% CI: 1.04–1.26 for allele contrast). In the subgroup analysis by cancer types, significant associations were found in breast cancer (OR?=?1.66, 95% CI: 1.24–2.21 for TT vs. CC; OR?=?1.44, 95% CI: 1.14–1.82 for recessive model; OR?=?1.41, 95% CI: 1.10–1.81 for domain model; and OR?=?1.31, 95% CI: 1.13–1.52 for allele contrast) and renal cancer (OR?=?1.99, 95% CI: 1.37–2.90 for TT vs. CC; OR?=?1.74, 95% CI: 1.25–2.42 for domain model; OR?=?1.43, 95% CI: 1.09–1.88 for recessive model; and OR?=?1.40, 95% CI: 1.17–1.68 for allele contrast). However, no significant associations were found in colorectal cancer, gastric cancer, and acute lymphoblastic leukemia for all genetic models. In the ethnicity subgroup analysis, a significant association with cancer among Caucasians was found under the dominant model, homozygote comparison, CT versus CC comparison, and allele comparison.

Conclusions

In summary, this meta-analysis suggests that the MDR1 C3435T polymorphism is associated with cancer susceptibility, increasing the risk of breast and renal cancer.     

Role of the PXR gene locus in inflammatory bowel diseases

BACKGROUND: The pregnane X receptor gene (PXR/NR1I2) has been recently associated with an increased risk for inflammatory bowel disease (IBD), although a subsequent case-control study failed to replicate the original association in an independent population. This nuclear receptor regulates genes involved in the detoxification process in the liver and intestine, like ABCB1/MDR1. PXR expression was significantly reduced in the colon of patients with ulcerative colitis (UC), but remained unaffected in Crohn's disease (CD) patients. Considering previous results, we aimed at investigating the impact of this locus on IBD predisposition in the Spanish population.METHODS: Three PXR polymorphisms, including the 1 more strongly correlated with IBD risk in the initial study at -25385C/T (rs3814055) and the 6 haplotypes conformed by them, were analyzed in 365 UC and 331 CD patients and compared with 550 ethnically matched controls.RESULTS: The overall haplotypic distribution showed a significant difference between UC and CD patients (P = 0.05; chi(2) = 10.84). Among UC patients a significant difference was seen between those with extensive colitis and controls (P = 0.004; chi(2) = 17.04), mainly due to the presence of a risk haplotype (rs3814055*T//rs6784598*C//rs2276707*C: P = 0.001; odds ratio [OR] = 1.66, 95% confidence interval [CI] 1.20-2.30). Patients with extensive UC carrying the -25385T allele showed increased susceptibility compared with left-sided colitis patients and with healthy subjects. In patients with extensive UC a significantly different distribution of genotypes of the MDR1 G/A change located in intron 3 (rs3789243) was observed between carriers/noncarriers of the -25385T risk allele (P = 0.005).CONCLUSIONS: Our data seem to support the association of the PXR locus with extensive UC and the interaction between PXR and MDR1 genes.