细胞色素P450基因遗传多态性的研究进展

细胞色素P450（cytochrome P450，CYP）在众多外源性物质和内源性物质的代谢中具有重要作用。家族1-3中编码P450的基因均存在多态性，特别是CYP2C9、CYP2C19、CYP2D6和CYP3A5。超过一半的临床药物是由多态性P450介导代谢，CYP基因的多态性是造成药物反应个体差异的主要原因。近几年，许多与P450酶活性和CYP基因表达相关的等位基因已被鉴定，因此通过分型CYP基因的功能性遗传变异或标签（Tag）遗传变异，就可以获得个体的代谢表型，有助于医生及时找到正确的用药方案，有效地提高药物疗效和降低毒副作用，特别是那些治疗指数窄的药物。显然，了解CYP基因的遗传变异对于临床药物治疗和药物开发是必不可少。基因芯片技术具有高多重水平和高通量的特点，使同时分型大量CYP基因遗传变异成为可能，是实现个性化医疗的重要技术保障。然而，DNA制备制约了预测性CYP基因分型芯片的发展，其在临床上的广泛应用尚需时日。     

细胞色素P450 2C19基因多态性与肺癌遗传易感性

目的 通过对肺癌组及对照组细胞色素P450 2C19(cytochrome P450 2C19,CYP2C19)等位基因进行基因分型,探讨CYP2C19基因中G681A和G636A多态性的分布与肺癌易感性的关系.方法 提取293例肺癌患者和300例健康对照组患者的外周血基因组DNA,用实时荧光PCR方法对CYP2C19进行基因分型.对肺癌组和健康对照组基因分布进行比较.结果 肺癌组CYP2C19* 2/*3基因型显著高于正常对照组,差异有统计学意义(18.77％ vs 5.67％;P=0.000),对照组CYP2C19* 1/*2基因型显著高于肺癌组,差异有统计学意义(30.67％ vs 13.99％;P=0.000).两组病例CYP2C19代谢型分布比较结果,肺癌组慢代谢型频率超过对照组一倍以上(33.45％ vs 15.33％).肺癌与各相关指标的多因素Logistic 相关分析结果显示,CYP2C19慢代谢型可能是肺癌发生的独立危险因素(P=0.000,OR:2.755,95％ CI:1.748 ～4.343).结论 CYP2C19慢代谢型可能与肺癌的发生有关.     

药物代谢酶CYP2D6基因多态性及表型的研究进展

CYP2D6是人体内细胞色素P450家族中一种重要的药物代谢酶,其催化的药物种类广泛.多年研究表明,编码该酶的基因存在遗传多态性且该多态性与药物代谢、药物不良反应(adverse drug reaction,ADR)的产生和致癌物的活化关系密切.随着人类基因组计划的完成和基因多态性研究计划的开展,近年来对该基因多态性及其与表型关系的研究再次成为遗传药理学研究的热点.本文从CYP2D6基因多态性及其发生机制,多态性对药物代谢、相关疾病易感性的影响等四个方面对此进行综述.     

药物代谢酶CYP2D6基因多态性及表型的研究进展

CYP2D6是人体内细胞色素P450家族中一种重要的药物代谢酶,其催化的药物种类广泛.多年研究表明,编码该酶的基因存在遗传多态性且该多态性与药物代谢、药物不良反应(adverse drug reaction,ADR)的产生和致癌物的活化关系密切.随着人类基因组计划的完成和基因多态性研究计划的开展,近年来对该基因多态性及其与表型关系的研究再次成为遗传药理学研究的热点.本文从CYP2D6基因多态性及其发生机制,多态性对药物代谢、相关疾病易感性的影响等四个方面对此进行综述.     

炎症状态对CYP2B6活性改变及其作用机制的研究进展

肝脏细胞色素P450(cytochrome P450,CYP450)氧化酶又称混合功能氧化酶和单加氧酶,广泛存在于动物、植物、微生物的各种组织中,是负责大多数临床药物、环境致癌物、外源毒物及内源活性物质生物转化的主要酶系统,具有重要的药理、生理及病理学意义。CYP450是一类亚铁血红素-硫醇盐蛋白的基因超家族,由不同的基因家族和亚家族组成,其中与药物代谢关系最为密切的主要有CYP1A2、CYP2B6、CYP2C9、CYP2D6、CYP2E1及CYP3A4等。     

福建汉族氯吡格雷药物代谢相关基因CYP2C19的多态性分布研究

目的 探讨中国福建汉族人群与氯吡格雷代谢相关的CYP2C19基因多态性的分布.方法 采用聚合酶链反应-限制性片段长度多态性检测以及直接测序对1001名无亲缘关系的福建汉族志愿者进行CYP2C19*2、CYP2C19*3以及CYP2C19* 17基因型的检测.结果 在全部对象中,CYP2C19*2、*3和*17的频率分别为32.4％、5.8％和0.4％.根据CYP2C19基因多态位点功能代谢分型,携带CYP2C19*2或*3的中间代谢型(*1/*2和*1/*3)与弱代谢型(*2/*2和*2/*3)分别占47.95％和13.99％.该结果与日本、韩国、新加坡、马来西亚、泰国人群及中国的傣族、蒙古族、黎族和回族相似(P＞0.05),但是与中国的哈萨克族及维吾尔族,以及伊朗、俄罗斯、意大利、波兰、挪威、加拿大印第安人、玻利维亚、埃及、坦桑尼亚等国家的人种差异有统计学意义(P＜0.05).结论 氯吡格雷药物代谢相关基因CYP2C19的分布存在种族(地区)差异.该多态在中国福建汉族人群中的分布与中国傣族、蒙古族、黎族、回族及部分东亚、东南亚人群无明显差异,但与中国哈萨克族和维吾尔族以及部分欧洲、南美洲和非洲人群相比有较多的中间代谢型及弱代谢型(P＜0.05).     

细胞色素P450酶2C19基因多态性对氟西汀治疗抑郁症患者疗效的影响

目的:探讨细胞色素P450酶2C19(CYP2C19)基因多态性对氟西汀治疗抑郁症患者疗效的影响.方法:连续招募152例抑郁症患者,采用DNA微阵列芯片法检测CYP2C19基因型.依据CYP2C19基因检测结果,将患者分为快代谢组、中等代谢组和慢代谢组,三组患者均单用氟西汀抗抑郁治疗,连续用药4周,记录三组治疗前后汉密尔顿抑郁量表17项(HAMD-17)评分及治疗过程中副反应量表(TESS)评分情况,以HAMD-17减分率≥50％定义为有效,二元logistic回归分析影响治疗效果的因素.结果:快代谢组、中代谢组和慢代谢组分别有58例(38.2％)、71例(46.7％)和23例(15.1％)患者.治疗前,三组HAMD-17评分差异无显著性;治疗后,慢代谢组HAMD-17评分显著低于快代谢组和中等代谢组(P＜0.05);患者分组与治疗时间有交互作用(F=4.891,P=0.014),三组HAMD—17评分随治疗时间的变化趋势不同;慢代谢组治疗有效率显著高于快代谢组(P＜0.05);治疗过程中,三组TESS评分差异无显著性;二元logistic回归分析显示,患者的病程(OR=0.576,P=0.012)是氟西汀抗抑郁治疗效果的独立影响因素,CYP2C19基因快代谢型患者应用氟西汀抗抑郁治疗有效的可能性是慢代谢型患者的22.6％(OR=0.226,P=0.009).结论:CYP2C19慢代谢型患者应用氟西汀抗抑郁治疗疗效较好,CYP2C19基因多态性对氟西汀抗抑郁症治疗有影响.     

细胞色素P4503A基因表达调控及与抗癫痫药物的关系

细胞色素P4503A酶(Cytochrome P450 3A enzymes)在外源性化合物尤其是药物代谢中起重要作用,临床中约有50%的药物经由CYP3A代谢,其中包括多种抗癫痫药物.本文概述了CYP3A的基因家系的结构、分布和调控表达的异同,CYP3A与难治性癫痫患者药物难治性的可能机制--多药耐药基因和P-糖蛋白的关系,CYP3A4基因表达上的差别与药物作用强度和持续时间、急性毒性的相关性.     

CYP2C19、ALDH2和MTHFR基因多态性与冠心病的相关性研究

目的 探讨细胞色素P450 2C19 (cytochrome P450 2C19,CYP2C19)、乙醛脱氢酶2(acetaldehyde dehydrogenase 2,ALDH2)和亚甲基四氢叶酸还原酶(methylene tetrahydrofolate reductase,MTHFR)基因多态性与冠心病的相关性.方法 分别采用DNA微阵列芯片技术和PCR-芯片杂交方法,对187例冠心病患者和166名健康体检者的CYP2C19、ALDH2和MTHFR位点进行多态性分析.结果 CYP2C19*2/*2、ALDH2 AA和MTHFR TT基因型及频率在冠心病组分别为8.9％、12.3％和34.9％,在对照组分别为3.6％、1.8％和4.1％,两组比较,差异均具有统计学意义(P＜0.05);Logistic回归分析发现ALDH2和MTHFR基因多态性是冠心病发生的重要危险因素,ALDH2 GA和AA基因型:OR值=2.09,MTHFR CT和TT基因型:OR值=2.11.结论 ALDH2和MTHFR基因多态性可增加冠心病的发生风险.     

细胞色素P4501A1基因多态性及其与肿瘤易感性研究进展

细胞色素P450(Cytochrome P ,CYP) 1A1是一种重要的P450系氧化代谢酶,广泛分布于肝外组织,催化多种前致癌剂的活化并且在雌激素代谢中起作用。目前发现四种重要的多态性位点,即 3801 T→C 、Ile462Val 、3205T→C、Thr461→Asp,CYP1A1基因多态性与多种肿瘤的易感性相关。     

Combination Analysis in Genetic Polymorphisms of Drug-Metabolizing Enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A5 in the Japanese Population

The Cytochrome P450 is the major enzyme involved in drug metabolism. CYP enzymes are responsible for the metabolism of most clinically used drugs. Individual variability in CYP activity is one important factor that contributes to drug therapy failure. We have developed a new straightforward TaqMan PCR genotyping assay to investigate the prevalence of the most common allelic variants of polymorphic CYP enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A5 in the Japanese population. Moreover, we focused on the combination of each genotype for clinical treatment. The genotype analysis identified a total of 139 out of 483 genotype combinations of five genes in the 1,003 Japanese subjects. According to our results, most of subjects seemed to require dose modification during clinical treatment. In the near future, modifications should be considered based on the individual patient genotype of each treatment.     

Pharmacogenetics of schizophrenia

Patients display significant differences in response to therapeutic agents which may be caused by a variety of factors. Among them, genetic components presumably play a major role. Pharmacogenetics is the field of research that attempts to unravel the relationship between genetic variation affecting drug metabolism (pharmacokinetic level) or drug targets (pharmacodynamic level) and interindividual differences in pharmacoresponse. In schizophrenia, pharmacokinetic studies have shown the role of genetic variants of the cytochrome P450 enzymes CYP2D6, CYP2C19, and CYP2C9 in the metabolism of neuroleptic drugs. At the level of the drug target, variants of the dopamine D3 and D4, and 5-HT2A and 5-HT2C receptors have been examined. A general problem of pharmacogenetic studies in schizophrenia is the high number of controversial findings which may be related to the lack of standardized phenotype definition. Recently, guidelines for an exact and comparable phenotype characterization have been proposed and will aid in designing and evaluating pharmacogenetic studies in the future. The final goal of pharmacogenetic studies-making a prediction of drug response at the level of the individual patient-will require a simultaneous look at a large number of response-determining genetic variants by applying the tools of pharmacogenomics, e.g. large-scale Single Nucleotide Polymorphism (SNP) detection and genotyping.     

Flexible and Scalable Full‐Length CYP2D6 Long Amplicon PacBio Sequencing

Cytochrome P450 2D6 (CYP2D6) is among the most important genes involved in drug metabolism. Specific variants are associated with changes in the enzyme's amount and activity. Multiple technologies exist to determine these variants, like the AmpliChip CYP450 test, Taqman qPCR, or Second‐Generation Sequencing, however, sequence homology between cytochrome P450 genes and pseudogene CYP2D7 impairs reliable CYP2D6 genotyping, and variant phasing cannot accurately be determined using these assays. To circumvent this, we sequenced CYP2D6 using the Pacific Biosciences RSII and obtained high‐quality, full‐length, phased CYP2D6 sequences, enabling accurate variant calling and haplotyping of the entire gene‐locus including exonic, intronic, and upstream and downstream regions. Unphased diplotypes (Roche AmpliChip CYP450 test) were confirmed for 24 of the 25 samples, including gene duplications. Cases with gene deletions required additional specific assays to resolve. In total, 61 unique variants were detected, including variants that had not previously been associated with specific haplotypes. To further aid genomic analysis using standard reference sequences, we have established an LOVD‐powered CYP2D6 gene‐variant database, and added all reference haplotypes and data reported here. We conclude that our CYP2D6 genotyping approach produces reliable CYP2D6 diplotypes and reveals information about additional variants, including phasing and copy‐number variation.     

Review of evidence for genetic testing for CYP450 polymorphisms in management of patients with nonpsychotic depression with selective serotonin reuptake inhibitors

PurposeCytochrome P450 (CYP450) enzymes metabolize selective serotonin reuptake inhibitor (SSRI) drugs used in treatment of depression. Variants in these genes may impact treatment efficacy and tolerability. The purpose of this study was 2-fold: to systematically review the literature for evidence supporting CYP450 genotyping to guide SSRI treatment for major depression, and, where evidence is inadequate, to suggest future research.MethodsWe searched MEDLINE® and other databases for studies addressing five key questions suggested by the Evaluation of Genomic Applications in Practice and Prevention Working Group. Eligibility criteria were defined, and studies were reviewed independently by paired researchers. A conceptual model was developed to guide future research.ResultsReview of 1200 abstracts led to the final inclusion of 37 articles. The evidence indicates relatively high analytic sensitivity and specificity of tests detecting a subset of polymorphisms of CYP2D6, 2C19, 2C8, 2C9, and 1A1. We found marginal evidence regarding a clinical association between CYP450 variants and SSRI metabolism, efficacy, and tolerability in the treatment of depression.ConclusionsCurrent evidence does not support the use of CYP450 genotyping to guide SSRI treatment of patients with depression. Studies are proposed that will effectively guide decision-making in the area of CYP450 testing in depression, and genetic testing more generally.     

Clinical guidelines for psychiatrists for the use of pharmacogenetic testing for CYP450 2D6 and CYP450 2C19

Pharmacogenetics has arrived in clinical psychiatric practice with the FDA approval of the AmpliChip CYP450 Test that genotypes for two cytochrome P450 2D6 (CYP2D6) and 2C19 (CYP2C19) genes. Other pharmacogenetic tests, including those focused on pharmacodynamic genes, are far from ready for clinical application. CYP2D6 is important for the metabolism of many antidepressants and antipsychotics, and CY2C19 is important for some antidepressant metabolism. Poor metabolizers (PMs), lacking the enzyme, account for up to 7% of Caucasians for CYP2D6 and up to 25% of East Asians for CYP2C19. Patients having three or more active CYP2D6 alleles (up to 29% in North Africa and the Middle East), are called CYP2D6 ultra-rapid metabolizers (UMs). CYP2D6 phenotypes (particularly PMs) are probably important in patients taking tricyclic antidepressants (TCAs), venlafaxine, typical antipsychotics, and risperidone. The CYP2C19 PM phenotype is probably important in patients taking TCAs and perhaps citalopram, escitalopram, and sertraline. On the basis of the literature and the authors' clinical experience, the authors provide provisional recommendations for identifying and treating CYP2D6 PMs, CYP2C19 PMs, and CYP2D6 UMs. The next few years will determine whether CYP2D6 genotyping is beneficial for patients taking the new drugs aripiprazole, duloxetine, and atomoxetine. Practical recommendations for dealing with laboratories offering CYP2D6 and CYP2C29 genotyping are provided.     

Assay for the simultaneous detection of the *1C and *1F alleles of the CYP1A2 gene by real-time polymerase chain reaction and melting curve analysis

Pharmacogenetic variation is an important factor in the therapeutic outcome of many drug treatments. The cytochrome P450 isoform CYP1A2 is involved in the metabolism of a number of antipsychotic drugs. Variable expression of this enzyme may result in idiosyncratic drug responses, including adverse reactions. A number of DNA sequence polymorphisms have been identified in the CYP1A2 gene. Of these, two alleles, CYP1A2*1C and CYP1A2*1F, have been linked to changes in gene expression among smokers. In addition, these polymorphisms have been linked to susceptibility to tardive dyskinesia in some patient populations receiving antipsychotic drug therapy. Here, we present a rapid and robust method for simultaneously genotyping the CYP1A2*1C and *1F alleles using fluorescent hybridization probes and a widely available real-time polymerase chain reaction platform. Such an assay would offer the opportunity to routinely establish the CYP1A2 genotype of a patient prior to commencing drug therapy.     

Evaluation of a microarray-based genotyping assay for the rapid detection of cytochrome P450 2C19 *2 and *3 polymorphisms from whole blood using nanoparticle probes

Numerous drugs such as clopidogrel have been developed to reduce coagulation or inhibit platelet function. The hepatic cytochrome P450 (CYP) pathway is involved in the conversion of clopidogrel to its active metabolite. A recent black-box warning was included in the clopidogrel package insert indicating a significant clinical link between specific CYP2C19 genetic variants and poor metabolism of clopidogrel. Of these variants, *2 and *3 are the most common and are associated with complete loss of enzyme activity. In patients who are carriers of a CYP2C19 *2 or *3 allele, the conversion of clopidogrel to its active metabolite may be reduced, which can lead to ischemic events and negative consequence for the patient. We examined the ability of the Verigene CLO assay (Nanosphere, Northbrook, IL) to identify CYP2C19 *2 and *3 polymorphisms in 1,286 unique whole blood samples. The Verigene CLO assay accurately identified homozygous and heterozygous *2 and *3 phenotypes with a specificity of 100% and a final call rate of 99.7%. The assay is fully automated and can produce a result in approximately 3.5 hours.     

Molecular basis of polymorphic drug metabolism

Genetic polymorphisms with functional effects occur in many of the genes encoding drug metabolizing enzymes and are an important cause of adverse drug reations. Recent advances in the understanding of the molecular genetics of drug-metabolizing enzymes, particularly the cytochromes P450, has enabled the molecular basis of several polymorphisms to be elucidated and genotyping assays using the polymerase chain reaction to be developed. Polymorphisms in this category include those in the cytochrome P450 genes CYP2D6, CYP2C19, CYP2A6, CYP2C9 and CYP2E1, the glutathione S-transferase genes GSTM1 and GSTT1 and the N-acetyltransferase gene NAT2. The molecular basis and impotance to drug metabolism of the various polymorphisms as well as evidence for the existence of polymorphisms in other genes encoding drug-metabolizing enzymes such as the UDP-glucuronosyltransferases, the sulphotransferases and the methyltransferases are discussed.Abbreviations DHEA ST Dehydroepiandrosterone sulphotransferase - EST Oestrogen sulphotransferase - TL ST Thermolabile sulphotransferase - TS ST Thermostable sulphotransferase