MDR1 (ABCB1) gene polymorphism C3435T is associated with P-glycoprotein activity in B-cell chronic lymphocytic leukemia

Functional single nucleotide polymorphism (SNP) C3435T in exon 26 of the MDR1 ( ABCB1 ) gene encoding the xenobiotic transporter P-glycoprotein (P-gp, MDR1, ABCB1) may influence susceptibility to several diseases as well as clinical outcome of treatment with P-gp substrates. Exposure to environmental chemicals is thought to be involved in the pathogenesis of B-cell chronic lymphocytic leukemia (B-CLL) and P-gp-transported drugs are used in its treatment; however, little is known about the impact of the C3435T MDR1 SNP in B-CLL. In this study, 110 Caucasian B-CLL patients and 201 healthy controls were genotyped for the MDR1 C3435T SNP. Additionally, P-gp activity was assessed in malignant lymphocytes of 22 untreated B-CLL patients. We observed a higher frequency of carriers of at least one 3435T allele (3435CT and 3435TT genotypes) among B-CLL patients as compared to normal individuals (76% vs . 63%, p=0.027). The genotypes 3435CT and 3435TT were associated with B-CLL, (odds ratio=1.8, 95% confidence interval = 1.1-3.0). Moreover, P-gp activity in B-CLL cells depended on MDR1 genotype, with the highest P-gp activity in 3435CC homozygotes, intermediate in 3435CT heterozygotes and the lowest in 3435TT homozygotes (p=0.042). P-gp activity was also significantly lower in carriers of the T-allele (3435CT/TT genotype) as compared to the non-carriers (3435CC genotype), (p=0.029). Taken together, these data indicate that the MDR1 C3435T SNP may carry an increased risk of developing B-CLL, possibly by virtue of decreased protection against P-gp-substrate carcinogens. The differences in P-gp activity in B-CLL tumor cells related to MDR1 genotype may have implications to the response to chemotherapy with P-gp transported anticancer agents.     

Allele and genotype frequency of MDR1 C3435T in Tamilian population

The allele and genotype frequencies of MDR1 C3435T polymorphism were determined in 185 unrelated healthy Tamilians. The genomic DNA was extracted from peripheral leucocytes using phenol chloroform method and genotyped by PCR-RFLP method. The frequencies of MDR1 C3435 and T3435 alleles in Tamilian population were 0.46 and 0.54 respectively. The distribution of T3435 in this population was found to be greater than Africans and almost similar to Caucasians and Orientals. The distribution of CC, CT and TT genotypes was 0.18, 0.56 and 0.26 respectively. The frequency distribution of the CC genotype was lower in them when compared with Chinese and Africans whereas CT genotype was higher in comparison with all the major ethnic groups.     

Distinct haplotype profiles and strong linkage disequilibrium at the MDR1 multidrug transporter gene locus in three ethnic Asian populations

The MDR1 multidrug transporter plays a key role in determining drug bioavailability, and differences in drug response exist amongst different ethnic groups. Numerous studies have identified an association between the MDR1 single nucleotide polymorphism (SNP) exon 26 3435C>T and differences in MDR1 function. We performed a haplotype analysis of the MDR1 gene in three major ethnic groups (Chinese, Malays and Indians) by examining 10 intragenic SNPs. Four were polymorphic in all three ethnic groups: one occurring in the non-coding region and three occurring in coding exons. All three coding SNPs (exon 12 1236C>T, exon 21 2677G>T/A and exon 26 3435C>T) were present in high frequency in each ethnic group, and the derived haplotype profiles exhibited distinct differences between the groups. Fewer haplotypes were observed in the Malays (n = 6) compared to the Chinese (n = 10) and Indians (n = 9). Three major haplotypes (> 10% frequency) were observed in the Malays and Chinese; of these, two were observed in the Indians. Strong linkage disequilibrium (LD) was detected between the three SNPs in all three ethnic groups. The strongest LD was present in the Chinese, followed by Indians and Malays, with the corresponding LD blocks estimated to be approximately 80 kb, 60 kb and 40 kb, respectively. These data strongly support the hypothesis that strong LD between the neutral SNP exon 26 3435C>T and a nearby unobserved causal SNP underlies the observed associations between the neutral SNP and MDR1 functional differences. Furthermore, strong LD between exon 26 3435T and different unobserved causal SNPs in different study populations may provide a plausible explanation for conflicting reports associating the same exon 26 3435T allele with different MDR1 functional changes.     

Effect of MDR1 gene polymorphism on progression of end-stage renal disease

AIM: P-glycoprotein is localized at the apical brush-border membrane of the proximal renal tubule and functions as extruding toxins and xenobiotics out of cells. The difference of P-glycoproteinos function resulted from single nucleotide polymorphisms in MDR1 (multidrug resistance gene encoding for P-gp) and may be the cause of interindividual differences in susceptibility to end-stage renal disease (ESRD). The purpose of this study is to compare the genotype frequency of C3435T and G1199A polymorphisms in MDR1 between ESRD patients and healthy controls in the Chinese population to determine whether the alteration of the P-gp function is associated with ESRD. METHODS: Two hundred and eighty-four healthy Chinese controls and 244 Chinese patients with ESRD were involved in this study. Allele specific PCR and polymerase chain reaction-restriction fragment length polymorphism assay were used to determine the genotype MDR1 G1199A and C3435T, respectively. RESULTS: The genotype distribution of 3435CC, 3435CT, and 3435TT were 0.35, 0.50, and 0.15, respectively, in the control group and 0.38, 0.47, and 0.15 in the group with the ESRD patients. No variant allele 1199G>A was found in any of the patients. The value of serum creatinine for genotypes 3435CC, 3435CT, and 3435TT in the ESRD patients were 753.8+/-276.0 mumol/L, 849.6+/-342.2 micromol/L, and 987.0+/-512.0 micromol/L, respectively. The difference between 3435TT and 3435CC reached statistical significance (P<0.05). CONCLUSION: The low expression of P-glycoprotein was not the etiological factor for the kidney disease, but it may contribute to the progression of ESRD and affect the severity. Chinese people do not carry the 1199G>A variant allele. More studies are needed to clarify the cause and interindividual differences in the susceptibility for the risk of ESRD.     

多药抗药基因1 C3435T在中国佤族、白族和藏族人群中的基因多态性

目的了解中国佤族、白族和藏族人群中多药抗药基因1(MDR1)C3435T位点突变频率,并与其他种族比较,了解种族差异。方法使用聚合酶链反应-限制性片段长度多态性方法并用直接测序法对中国143名佤族、138名白族和257名藏族健康个体进行MDR1 C3435T基因分型。结果野生CC型在佤族、白族和藏族的频率分别为31.5%,29.7%和25.7%,突变杂合子CT型频率分别为44.7%,50.7%和56.8%,而突变纯合子TT型频率则分别为23.8%,19.6%和17.5%,分布符合Hardy-Weinberg平衡。MDR1 C3435T等位基因T在佤族、白族和藏族的频率分别为46.2%,44.9%和45.9%,与非洲裔美国人的比较有明显差异。佤族和藏族与汉族的比较有差异。结论中国佤族、白族和藏族人群MDR1C3435T位点的突变发生情况有自己的特点,在临床应用相关药物时,进行该位点基因型检测,将有助于指导临床个体化用药。     

An interethnic comparison of polymorphisms of the genes encoding drug-metabolizing enzymes and drug transporters: experience in Singapore

Much of the interindividual variability in drug response is attributable to the presence of single nucleotide polymorphisms (SNPs) in genes encoding drug-metabolizing enzymes and drug transporters. In recent years, we have investigated the polymorphisms in a number of genes encoding phase I and II drug-metabolizing enzymes including CYPIA1, CYP3A4, CYP3A5, GSTM1, NAT2, UGT1A1, and TPMT and drug transporter (MDR1) in three distinct Asian populations in Singapore, namely the Chinese, Malays, and Indians. Significant differences in the frequencies of common alleles encoding these proteins have been observed among these three ethnic groups. For example, the frequency of the variant A2455G polymorphism of CYP1A1 was 28% in Chinese and 31% in Malays, but only 18% in Indians. CYP3A4*4 was detected in two of 110 Chinese subjects, but absent in Indians and Malays. Many Chinese and Malays (61-63%) were homozygous for the GSTM1*0 null genotype compared with 33% of Indians. The frequency of the UGTIA1*28 allele was highest in the Indian population (35%) compared to similar frequencies that were found in the Chinese (16%) and Malay (19%) populations. More importantly, our experience over the years has shown that the pharmacogenetics of these drug-metabolizing enzymes and MDR1 in the Asian populations are different from these in the Caucasian and African populations. For example, the CYP3A4*1B allele, which contains an A-290G substitution in the promoter region of CYP3A4, is absent in all three Asian populations of Singapore studied, but occurs in more than 54% of Africans and 5% of Caucasians. There were no difference in genotype and allelic variant frequencies in exon 12 of MDR1 between the Chinese, Malay, and Indian populations. When compared with other ethnic groups, the distribution of the wild-type C allele in exon 12 in the Malays (34.2%) and Indians (32.8%) was relatively high and similar to the Japanese (38.55%) and Caucasians (41%) but different from African-Americans (15%). The frequency of wild-type TT genotype in Asians (43.5% to 52.1%) and Japanese (61.5%) was much higher than those found in Caucasians (13.3%). All the proteins we studied represent the primary hepatic or extrahepatic enzymes, and their polymorphic expression may be implicated in disease risk and the disposition of drugs or endogenous substances. As such, dose requirements of certain drugs may not be optimal for Asian populations, and a second look at the factors responsible for this difference is necessary.     

Distribution of allelic variants of functional C3435T polymorphism of drug transporter MDR1 gene in a sample of Polish population

P-glycoprotein (P-gp), the protein product of MDR1 gene, is an important factor regulating the bioavailability of many therapeutics. Recently, the C3435T polymorphism of MDR1 was correlated to altered expression and function of P-gp in normal tissues. In this study, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was applied to assess C3435T MDR1 polymorphism in 122 healthy individuals of Slavic origin from the population of central Poland (Lód? and surrounding areas). The detected genotype variant frequencies were as follows: CC in 42%, CT in 41%, and TT in 17% of the tested subjects (C-allele frequency was 0.62). The frequency of the C-allele is similar to Japanese population and significantly higher than in Caucasians from Western Europe. The results of this study give basis for large-scale C3435T MDR1 genotype-phenotype correlation investigations in Polish population that may be useful to individualize therapy of cancer, HIV-1 infection and some other diseases.     

MDR1 C3435T基因多态性对环孢素体内代谢影响的荟萃分析

目的 过荟萃分析进一步观察MDR1 3435T 基因多态性对于环孢素体内代谢的影响。方法 过Pubmed搜索C3435T基因多态性对于环孢素体内代谢影响的相关文献，提取AUC0-4，AUC0-12，AUC0-inf,Cmax,CL/F,和C0等药物动力学参数，使用STATA9.1软件进行荟萃分析。结果 共有14篇参考文献，包括1036名受试者符合本次荟萃分析的入选争件，荟萃分析显示在C3435T野生型杂合子（CC）中，AUC0-12低于其他基因型的受试者。在白种人中，C3435T野生型杂合子（CC）携带者的C0低于其他基因型的白种受试者。其他药物动力学参数在C3435T各基因型之间未见显著差异。结论本荟萃分析没有发现MDR1 C3435T基因多态性对于环孢素体内代谢有较大的影响，但是观察指标的选择是观察结果差异的原因之一；MDR1 C3435T表型和基因型的相关性可能存在种族差异．     

The MDR1 3435 polymorphism in patients with rheumatoid arthritis

OBJECTIVE: Rheumatoid arthritis (RA) is a multifactorial disease, the pathogenesis of which involves immunological, genetic and environmental factors. P-glycoprotein (P-gp) encoded by the MDR1 gene, is an important transporter for many drugs, xenobiotics and cytokines and may be associated with many immunological processes and apoptosis. The activity of P-gp is genetically determined. Naturally occurring MDR1 polymorphisms have been described and correlated with potential clinical effects. Several mutations in the MDR1 gene have been recognized, but only some of them are associated with P-gp expression. The C3435T polymorphism was found to correlate with the activity of P-glycoprotein. The aim of the study was to evaluate the C3435T MDR1 polymorphism in patients with rheumatoid arthritis and to investigate a possible correlation with disease susceptibility, activity and severity. METHODS: The study was carried out in 92 patients with rheumatoid arthritis and 97 healthy subjects as a control group. The C3435T polymorphism was determined using the PCR-RFLP method. RESULTS: The distribution of C3435TT MDR1 genotypes in RA patients did not differ significantly from that in a control group and was as follows: 3435CC in 25 (26.9%) subjects, 3435CT in 50 (53.8%) and 3435TT in 17 (18.3%). The probability of remission of RA symptoms after therapy with methotrexate and glucocorticosteroids however, was 2.89-fold greater in patients with the 3435TT genotype compared to patients with the genotypes 3435CC and 3435CT. The risk of having an active form of rheumatoid arthritis resistant to therapy with disease-modifying antirheumatic drugs in patients with 3435CC and 3435CT genotypes was 2.89 times greater than in homozygous 3435TT subjects. CONCLUSION: We suggest that the C3435T MDR1 polymorphism is not an important genetic risk factor for RA susceptibility, but that this polymorphism may have an influence on the activity of the disease and its response to therapy with disease-modifying antirheumatic drugs.     

Variable expression of P-glycoprotein in the human placenta and its association with mutations of the multidrug resistance 1 gene (MDR1, ABCB1)

The MDR1 gene product P-glycoprotein in the human placenta is important for protecting the fetus from unintended, harmful drug exposure, but also for limiting the access of therapeutic drugs to the fetus after maternal drug intake. A polymorphism in exon 26 of the MDR1 gene (C3435T) has previously been shown to be associated with reduced P-glycoprotein expression in the small intestine, kidney and lymphocytes. In the present study, we examined systematically whether MDR1 polymorphisms also have an impact on P-glycoprotein expression in the human placenta. MDR1 mRNA and P-glycoprotein were analysed in 73 full-term human placentas of Caucasians, as well as respective MDR1 genotypes/haplotypes, for the C3435T and G2677T/A polymorphisms of mothers and infants. MDR1 mRNA levels were not different between these genotype groups. However, P-glycoprotein expression was significantly lower when both mother and infant were homozygous for the 3435T allele (TT/tt) compared to maternal and fetal homozygotes for the C-allele (0.40 +/- 0.18 a.u. for TT/tt versus 0.66 +/- 0.30 a.u. for CC/cc, P = 0.01). Moreover, placentas from mothers carrying both polymorphisms (3435T and 2677T; TT/TT) also had a significantly lower P-glycoprotein expression (0.31 +/- 0.12 a.u.) compared to placentas of wild-type individuals (CC/GG, 0.71 +/- 0.31 a.u., P = 0.02). Taken together, the MDR1 polymorphisms C3435T and G2677T are associated with altered P-glycoprotein expression in the human placenta, and may have clinical consequences due to genetically determined, variable drug exposure of the fetus.     

The effect of CYP3A5 and MDR1 polymorphic expression on cyclosporine oral disposition in renal transplant patients

Variability in CYP3A (CYP3A4/5) and P-glycoprotein (human MDR1 gene product) activity underlies interindividual differences in oral cyclosporine (CsA) bioavailability. Racial differences in polymorphic expression of CYP3A5 and MDR1 may explain observed interracial variability in oral bioavailability. Our objective was to evaluate the effect of CYP3A5 and MDR1 polymorphic expression on CsA oral disposition. Steady-state plasma concentration profiles (n = 19) were sampled in renal transplant recipients receiving concentration-adjusted CsA maintenance therapy. CsA plasma concentrations were measured by fluorescence polarization immunoassay. CYP3A5 and MDR1 genotypes were determined by real-time polymerase chain reaction. Noncompartmental pharmacokinetic analysis and nonlinear mixed-effects modeling (NONMEM) were performed to assess the effect of genotype on CsA pharmacokinetics. MDR1 C3435T genotype was identified as the best predictor of CsA systemic exposure. CsA oral clearance was significantly higher in subjects who carried at least one 3435T allele compared to homozygous wild-type individuals (40.0 +/- 2.2 vs. 26.4 +/- 3.1 L/h, p = 0.007). MDR1 C3435T genotype accounted for 43% of the interindividual variability of CsA oral clearance in the study population after accounting for interoccasion variability. The authors were unable to independently assess whether CYP3A5 correlated with any CsA pharmacokinetic parameter since all CYP3A5 nonexpressors were also 3435T allele carriers. MDR1 3435T allele carriers have enhanced oral clearance compared to individuals with the CC genotype. The frequency of the 3435T allele is lower in African Americans compared to Caucasians. Thus, the MDR1 C3435T genotype offers a potential mechanistic basis to explain interracial differences in CsA oral bioavailability. Further studies are needed to explore the relationship between CYP3A5 and MDR1 genotype and phenotype.     

MDR1基因多态性对口服环孢素A药代动力学的影响

目的非线性混合效应模型(NONMEM)考察中国健康人多药耐药基因(MDR1)中26外显子的C3435T多态性与环孢素A (CsA)药代动力学特性间的关系。方法HPLC法测定20名健康男性单次口服CsA微乳溶液制剂500 mg后24 h内不同时间点的药物浓度。MDR1的基因多态性测定采用DNA限制性片段长度多态性法，并用基因测序法验证。数据处理与模型拟合采用NONMEM法。结果中国健康人中含MDR1 C3435T CC或CT型的相对生物利用度较TT型高40%。结论MDR1中C3435T多态性是个体间CsA相对生物利用度差异的影响因素。     

Meta-analysis of the influence of MDR1 C3435T polymorphism on digoxin pharmacokinetics and MDR1 gene expression

AIMS: Studies revealing conflicting results of the functional significance of MDR1 exon 26 C3435T SNP on the disposition of digoxin in different ethnic groups led us to perform a meta-analysis on published data investigating the influence of C3435T SNP on the pharmacokinetics of digoxin and the expression of MDR1. METHODS: Meta-analysis was performed on data from published studies investigating the influence of MDR1 C3435T SNP on digoxin pharmacokinetics, as well as MDR1 expression in Caucasian and Japanese populations. The following outcomes were included: exposures to digoxin measured by area under the concentration-time curve and maximum concentration, the mean intestinal MDR1 mRNA expression and P-gp expression in the absence of digoxin administration. RESULTS: The overall results of the meta-analysis in Caucasian and Japanese subjects suggested no major influence of the C3435T SNP on exposure levels of digoxin as determined by AUC(0-4 h) or AUC(0-24 h) although C(max) values for digoxin were lower in wild-type (CC) subjects compared with subjects harbouring TT genotypes. Subgroup analysis by ethnic populations showed the oral availability of digoxin to be lower in wild-type Caucasian populations compared with wild-type Japanese subjects. No causal relationships were detected between the C3435T SNP and MDR1 mRNA or protein expression. CONCLUSIONS: Our meta-analysis of available studies indicates that the synonymous MDR1 C3435T SNP does not affect the pharmacokinetics of digoxin and the expression of MDR1 mRNA. Future studies should focus on the impact of MDR1 haplotypes on the pharmacokinetics of MDR1 substrates rather than the C3435T SNP alone.     

Polymorphism in the P-glycoprotein drug transporter MDR1 gene in renal transplant patients treated with cyclosporin A in a Polish population

P-glycoprotein (P-gp), the product of MDR1 gene, is a protein which mediates transmembrane transport of a great number of xenobiotics including cyclosporin A used as an immunosuppressive drug in patients with allogenic kidney grafts. The P-gp activity and expression is dependent on the MDR1 gene polymorphism in position C3435T of exon 26. In this study, C3435T polymorphism was analyzed in 116 patients with allogenic kidney graft treated with cyclosporin Aand 144 randomly selected healthy individuals. The prevalence of MDR1 gene genotypes 3435CC, 3435CT, 3435TT were also compared in patients after allogenic kidney graft with both acute and chronic graft rejection (48 patients with acute and 76 with chronic graft rejection) and control groups (respectively 139 and 112). The results of the study demonstrated that the allelic frequency and MDR1 genotype distribution were similar in all evaluated groups. It was revealed that MDR1 gene polymorphism was not a predisposing factor for terminal kidney failure leading to renal transplantation. Moreover, evaluation of C3435T polymorphism of MDR1 gene will probably not be useful for characterization of groups of patients at increased risk of acute and chronic kidney graft rejection.     

Distribution of the FcgammaRIIIa 176 F/V polymorphism amongst healthy Chinese, Malays and Asian Indians in Singapore

AIMS: To determine and compare the distribution of the FcgammaRIIIa 176 F/V polymorphism across three ethnically distinct populations (Chinese, Asian Indians and Malays) in Singapore. METHODS: The FcgammaRIIIa 176 F/V polymorphism was genotyped by direct sequencing from genomic DNA samples obtained from normal healthy Chinese, Asian Indians and Malays (n = 192 from each population). RESULTS: The allelic frequencies of the high binding affinity FcgammaRIIIa 176 V allele for Chinese, Asian Indians and Malays were 35%, 33% and 46%, respectively (F allele frequencies were 65%, 67% and 54%, respectively). Genotype distributions were found to conform to the Hardy-Weinberg law (P > 0.05) in each group. chi(2) comparisons revealed significant differences in the genotype distributions of the FcgammaRIIIa 176 V/F polymorphism of Malays from the other two populations (Chinese and Asian Indians). However, no significant difference in the genotype distributions of the FcgammaRIIIa 176 V/F polymorphism was observed between Chinese and Asian Indian populations. CONCLUSIONS: The genotype distributions of the FcgammaRIIIa 176 V/F polymorphism in healthy Malays are significantly different from both Chinese and Indians. These observations provide the fundamentals on which future disease associations may be built and also present important implications for the design of therapeutic regimens amongst various ethnic groups.     

ABCB1 C3435T and G2677T/A polymorphism decreased the risk for steroid-induced osteonecrosis of the femoral head after kidney transplantation

Advances in transplantation technology have brought about great benefits to patients suffering from organ failure, but the problem still remains of complications induced by steroids used for post-transplant immunosuppression. Among the side-effects caused by steroids, non-traumatic osteonecrosis of the femoral head (ONF) constitutes a serious problem. The same protocol for steroid administration induces ONF in some patients, but not in others, indicating the presence of individual difference in steroid sensitivity. We hypothesized that this difference might be mediated by the drug-transport protein, P-glycoprotein (P-gp), and investigated the relationship between single nucleotide polymorphisms in the multidrug resistance gene 1 (ABCB1, MDR1) encoding P-gp and ONF. Subjects comprised 136 patients receiving kidney transplantation. Thirty patients developed post-transplant ONF. Genomic DNA was extracted from peripheral blood, and genotypes of ABCB1 C3435T (exon 26) and G2677T/A (exon 21) were determined by direct sequencing. Multivariate analyses based on clinical information were performed to determine the relationship between ABCB1 genotypes and ONF. The dose/concentration (D/C) ratios of tacrolimus were also determined to estimate the activity of P-gp in patients with different genotypes of ABCB1 C3435T (CC, CT, TT), and in those who did and did not develop ONF. The ABCB1 3435TT genotype showed a significantly lower incidence of ONF (adjusted odds ratio = 0.10, P = 0.034). The D/C ratio in the 3435TT genotype was significantly higher than that in the 3435CC genotype. The D/C ratio in patients developing ONF was significantly higher than in those patients who did not develop ONF. The results suggest increased activity of P-gp in patients with the 3435TT genotype and in those who did not develop ONF. The ABCB1 2677 homozygous variant type also showed a lower incidence of ONF (adjusted odds ratio = 0.26, P = 0.056). The 3435T and 3435C alleles were in linkage disequilibrium with the 2677T and the 2677G alleles, respectively, in the study population. An assessment of C3435T and G2677T/A polymorphisms preceding steroid treatment could be useful for predicting the resistance to ONF development.     

C3435T polymorphism of the ABCB1 gene: impact on genetic susceptibility to peptic ulcers

The functional single nucleotide polymorphism (SNP) C3435T in exon 26 of the ABCB1 gene encoding the xenobiotic transporter P-glycoprotein (P-gp) may influence susceptibility to several diseases, as well as the clinical outcome of treatment with P-gp substrates. Exposure to environmental chemicals is thought to be involved in peptic ulcer pathogenesis and then later in stomach cancer development. About 80% of ulcers are associated with Helicobacter pylori infection, one of the risk factors of stomach cancer. P-gp-transported drugs are used in treatment of H. pylori. Therefore, a lack of effectiveness in eradication therapy can lead to chronic stomach inflammation and promote cancerogenesis. In this study, 196 patients with peptic ulcers divided into two groups with and without H. pylori infection and combined with 96 healthy controls were genotyped for the ABCB1 C3435T SNP. A trend towards higher incidence of the 3435TT genotype among peptic ulcer patients than in controls (p = 0.0983) was observed. Likewise, the 3435T allele was more frequent in groups suffering from peptic ulcers. The association was near to statistical significance (p = 0.0538). Between analyzed genotypes and H. pylori infection, statistically significant dependence was found (p = 0.0372). In addition, the CT genotype was associated with 1.56 times and the TT with 2.45 times higher prevalence of infection compared to the CC genotype. Asimilar association was present in a subgroup of peptic ulcer men (p = 0.0090). The isolated C3435T ABCB1 SNP is not a major factor for genetic susceptibility to peptic ulcer, but in a group of men who suffered from peptic ulcer, this polymorphism seemed to be a risk factor for H. pylori infection development.     

新疆维吾尔族人群SLC22A1基因的单核苷酸多态性研究

目的：研究有机阳离子转运体SLC22A1基因单核苷酸多态性（SNP）rs2282143位点（P341L,1022C>T）基因型和等位基因在中国新疆维吾尔族人群中的分布频率,并比较其与不同种族间的分布差异。方法：通过SNaPshot SNP分型技术检测276例新疆维吾尔族健康人群的SLC22A1基因SNP rs2282143位点的基因型,并与国际人类基因组单倍型图谱计划（HapMap）中不同国家或地区就该位点的SNP分型数据进行比较,分析基因型频率和等位基因频率间的差异。结果：在新疆维吾尔族健康人群中,SLC22A1基因rs2282143位点中CC基因型最常见,分布频率为90.9%;CT和TT基因型分布频率分别为8.4%、0.7%;最小等位基因T的分布频率为4.9%。新疆维吾尔族SLC22A1基因rs2282143位点的基因型频率和等位基因频率分布与黄种人群存在显著差异;而与高加索人群和黑人不存在显著差异,其中与约鲁巴人群的基因型频率存在显著差异,但与该人群的等位基因分布频率分布不存在显著差异。结论：新疆维吾尔族人群SLC22A1基因具有显著的基因多态性,其SNP rs2282143位点基因型和等位基因的分布频率与部分国家或地区人群存在较大差异,该差异对于有机阳离子转运体SLC22A1基因相关的疾病诊断、药物基因组学以及人类进化史方面的研究可能起重要作用。     

Meta-analysis of the effect of MDR1 C3435T polymorphism on cyclosporine pharmacokinetics

The published data revealed conflicting results of the polymorphism of MDR1 exon 26 SNP C3435T on the pharmacokinetics of cyclosporine; thus, the aim was to conduct a meta-analysis of significant magnitude to investigate the influence of SNP C3435T on the pharmacokinetics of cyclosporine. A literature search was conducted to locate the relevant papers by using the PubMed electronic source from 1997 and onwards. The pharmacokinetic parameters, including AUC(0-4), AUC(0-12), AUC(0-inf), C(max), CL/F and trough concentration (C(0)), were extracted and a meta-analysis was performed by using Stata version 9.1. A total of 14 papers concerning 1036 individuals were included in the meta-analysis. The overall results showed no major influence of SNP C3435T on the pharmacokinetic parameters, including AUC(0-4), AUC(0-inf), CL/F, C(max) and C(0), although AUC(0-12) was lower in subjects with CC genotype. A subanalysis by ethnic population showed that C(0) was lower in Caucasian individuals harbouring CC genotype. In conclusion, our meta-analysis of available studies has thus far failed to demonstrate a definitive correlation between the SNP C3435T in MDR1 gene and alterations in P-glycoprotein function that can result in altered pharmacokinetics of cyclosporine, although it was indicated in this meta-analysis that the carrier of CC genotype of the SNP C3435T of MDR1 had lower cyclosporine exposure presented as AUC(0-12) than those with at least one T allele. There seems to be ethnic differences in the relationship between the SNP C3435T of MDR1 and cyclosporine pharmacokinetics.     

MDR1基因C3435T多态性对重症肌无力患者环孢素血药浓度的影响

目的 :研究MDR1基因C3435T多态性与重症肌无力患者环孢素药物动力学的关系。方法 :采用荧光PCR的方法检测 96名重症肌无力 (MG)患者MDR1C3435T基因型 ,其中临床资料较全的 73名 ,对其环孢素用药的血药检测结果与基因型结果分析。结果 :重症肌无力患者MDR1C3435T的分布频率接近 1:1;野生型 3435CC患者的环孢素全血谷浓度高于杂合型和突变型 (P <0 .0 5 ) ,杂合型与突变型之间无明显差异。结论 :药物遗传学研究对环孢素治疗重症肌无力患者的临床合理用药有指导意义。