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.     

细胞色素P450基因多态性与药物代谢

细胞色素P450(cytochrome P450,CYP)在众多外源性和内源性物质的代谢中具有重要作用.CYP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基因的功能性或标签(Tag)的遗传变异,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的.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.     

CYP2C9基因多态性与药物代谢

肝细胞色素 CYP2 C9催化一系列药物在体内的生物转化。CYP2 C9基因多态性形成的个体差异是相关药物代谢差异的主要原因 ,本文综述了 CYP2 C9基因的主要多态性类型在不同人群中的分布状况以及多态性与相关药物代谢的关系     

CYP1A2基因C163A多态性与精神分裂症易感性的相关研究

<正>细胞色素P450在生物体广泛分布,参与多种药物的代谢,在许多疾病的发生、发展中都起到了重要作用。目前国内正在深入开展药物基因组学方面的研究,疾病与药物代谢酶基因多态性之间的关系研究在国际上也是一个热点。精神分裂症是一种由多因子共同作用而发生的复杂疾病,流行病学证据表明,遗传因素是该病发生的重要原因。国际上已经开展了有关于CYP1A2和精神分裂症关系的研究,而在国内相关报道较少,2005年印度学者报道了CYP1A2基因     

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。     

CYP2C9基因多态性与药物代谢

肝细胞色素CYP2C9催化一系列药物在体内的生物转化。CYP2C9基因多态性形成的个体差异是相关药物代谢差异的主要原因，本综述了CYP2C9基因的主要多态性类型在不同人群中的分布状况以及多态性与相关药物代谢的关系。     

细胞色素P4502D6酶基因多态性与右美沙芬氧化代谢的相关研究

目的　探讨中国人右美沙芬氧化代谢多态性的遗传机理。方法　采用聚合酶链反应和限制性片段长度多态性技术 ,对 119名健康汉族人的肝细胞色素 P45 0 2 D6 (CYP2 D6 )基因型进行分析。结果CYP2 D6 * 10 B的基因频率为 5 8.4% ,其中 13名 (10 .9% )为野生型 (w/ w) ,33名 (2 7.7% )为突变型 (m/ m) ,其余 73名 (6 1.3% )为杂合子 (m/ w)。右美沙芬中速代谢者 (intermediate metabolizer,IM)表型中有约 70 %是由 CYP2 D6 * 10 B m/ m造成的 ,而 1名弱代谢者 (poor metabolizer,PM)亦为 m/ m型。另外 ,10名受试者不存在与白种人 PM相关的 6种缺陷 CYP2 D6等位基因。结论　中国人 CYP2 D6 * 10 B等位基因的存在可以在很大程度上解释右美沙芬氧代谢酶活性的降低     

生物转化酶类基因多态性与肿瘤易感性

肿瘤易感性一直是肿瘤研究的重要课题 ,而生物转化酶类的细胞色素P4 5 0 (CYP4 5 0 )和谷胱甘肽转硫酶(GST)等由于其对环境致癌物的生物转化作用决定了个体对肿瘤的易感程度。通过介绍其中的CYP1A1、CYP2D6、CYP2E1、GSTM1和GSTT1等的基因多态性及其与机体易患肿瘤的关系 ,揭示了生物转化酶基因多态性在肿瘤易感性中的作用。国内外的研究结果表明 :CYP1A1基因多态性与肺癌的发生、CYP2E1基因多态性与食管癌的易感性均密切相关 ,GST的基因多态性虽然与多种肿瘤的易感性有关联但研究结果有的互相矛盾 ,提示机体肿瘤发生机理的复杂性。由于环境致癌物在体内需经一系列的生物转化而产生生物学效应 ,因而生物转化酶类基因多态性的联合作用在肿瘤的易感性中显得尤为重要     

苯及同系物接触者Ⅰ、Ⅱ相代谢酶基因多态性与CYP1A1酶活性关系研究

目的研究职业性接触苯系物与Ⅰ、Ⅱ相代谢酶CYP1A1、CYP2E1、GSTT1和GSTM1基因多态性对CYP1A1酶活性的影响。方法以52例广东省某公司苯系物接触者为接触组,以38例未接触苯系物的“正常人”为对照组,抽提外周血淋巴细胞,Ⅰ、Ⅱ相代谢酶基因多态性检测用PCR和PCR-RLCP方法,CYP1A1酶活性用EROD酶活性表示。结果与对照组比较,苯系物接触组CYP1A1酶活性显著高于对照组（P〈0.01）,但无性别差异。苯接触组中不同Ⅰ、Ⅱ相代谢酶CYP1A1、CYP2E1、GSTT1和GSTM1基因多态性CYP1A1酶活性差异无统计学意义。结论苯作业工人外周血CYP1A1酶的活性受到苯接触的诱导作用,但并未发现受Ⅰ、Ⅱ相代谢酶CYP1A1、CYP2E1、GSTT1和GSTM1基因多态性的影响。     

从药物遗传学到药物基因组学

本文介绍了药物遗传学的研究现状,并着重探讨三种细胞色素P450酶（CYP2C19,CYP2D6,CYP1A1）基因多态与药物代谢的关系,随着人们对人类基因组和人类基因组多样性研究的逐步深入,药物遗传学已发展到一个新的阶段－药物基因组学,它与传统的药物遗传学研究相比,有相近之处,但更有自己的特色和优势,并对现代医学的发展产生也深远的影响。     

Genetic Polymorphism of CYP2D6 and Clomiphene Concentrations in Infertile Patients with Ovulatory Dysfunction Treated with Clomiphene Citrate

CYP2D6 is primarily responsible for the metabolism of clomiphene citrate (CC). The purpose of the present study was to investigate the relationship between CYP2D6 genotypes, concentrations of CC and its major metabolites and drug response in infertility patients. We studied 42 patients with ovulatory dysfunction treated with only CC. Patients received a dose of 100 mg/day CC on days 3-7 of the menstrual cycle. CYP2D6 genotyping and measurement of CC and the major metabolite concentrations were performed. Patients were categorized into CC responders or non-responders according to one cycle response for the ovulation. Thirty-two patients were CC responders and 10 patients were non-responders with 1 cycle treatment. The CC concentrations were highly variable within the same group, but non-responders revealed significantly lower (E)-clomiphene concentration and a trend of decreased concentrations of active metabolites compared to the responders. Nine patients with intermediate metabolizer phenotype were all responders. We confirmed that the CC and the metabolite concentrations were different according to the ovulation status. However, our results do not provide evidence for the contribution of CYP2D6 polymorphism to either drug response or CC concentrations.     

Pheno- and genotyping the prescription of drugs metabolized by CYP2D6

Mutant alleles CYP2D63 and CYP2D64 were detected by PCR in 33 individuals. All examinees were given 50 mg methoprolol (orally). Plasma concentrations of the drug and its major metabolite was determined by high performance liquid chromatography and arterial pressure and heart rate were monitored. The rate of methoprolol metabolism was significantly lowered in subjects with CYP2D64 mutation. This determined blood pressure decrease and bradycardia in these subjects after drug intake.     

Elucidation of CYP2D6 Genetic Diversity in a Unique African Population: Implications for the Future Application of Pharmacogenetics in the Xhosa Population

Genetic variation of the CYP2D6 gene has been associated with altered drug metabolism; however, limited studies have investigated CYP2D6 sequence diversity in African populations. We devised a CYP2D6 genotyping strategy to analyse the South African Xhosa population and genotype a Xhosa schizophrenia cohort, as CYP2D6 metabolises many antipsychotics and antidepressants. The entire CYP2D6 gene locus was sequenced in 15 Xhosa control individuals and the data generated were used to design a comprehensive genotyping strategy. Over 25 CYP2D6 alleles were genotyped in Xhosa controls and Xhosa schizophrenia patients using long‐range PCR, DNA sequencing and single nucleotide primer extension analysis. Bioinformatic algorithms were used to predict the functional consequences of relevant mutations and samples were assigned CYP2D6 activity scores. A unique allele distribution was revealed and two rare novel alleles, CYP2D6*73 and CYP2D6*74, were identified. No significant differences in allele frequencies were detected between Xhosa controls and schizophrenia patients. This study provides i) comprehensive data on a poorly characterised population, ii) a valuable CYP2D6 genotyping strategy and iii) due to their unique genetic profile, provides the basis for pharmacogenetic intervention for Xhosa individuals.     

Characterization of a novel CYP2A7/CYP2A6 hybrid allele (CYP2A6*12) that causes reduced CYP2A6 activity

The human CYP2A6 enzyme metabolizes certain drugs and pre-carcinogens and appears to be the most important enzyme for nicotine metabolism. At present, more than 10 different allelic variants are known that cause abolished or decreased enzyme activity. Genetic polymorphism in this gene might be of particular importance for an individual's need for nicotine and for susceptibility to lung and/or liver cancer. We have identified a new CYP2A6 allele (CYP2A6*12) which carries an unequal crossover between the CYP2A6 and CYP2A7 genes in intron 2. This results in a hybrid allele where the 5' regulatory region and exons 1-2 are of CYP2A7 origin and exons 3-9 are of CYP2A6 origin, resulting in 10 amino acid substitutions compared to the CYP2A6(*)1 allele. Phenotyping with the CYP2A6 substrate coumarin indicates that it causes reduced CYP2A6 activity in'vivo. Furthermore, when expressed in mammalian COS-1 cells, the enzyme variant catalyzed 7-hydroxylation of coumarin at a rate approximately 60% of that of the wild-type enzyme. The CYP2A6(*)12 allele was present at an allele frequency of 2.2% among Spaniards, but was absent in Chinese.     

Adverse drug reaction monitoring in Jena: Relevance of polymorphic drug metabolizing enzymes for inducing adverse drug reactions

Inter-subject variability in therapeutic drug response and drug toxicity is a major problem in clinical practice. In this field genetic polymorphisms of drug metabolizing enzymes play an important role. In a multicenter study supported by the German Federal Institute for Drugs and Medical Devices (BfArM, Z 12.01-68502-201) adverse drug reactions (ADRs) leading to hospital admission to departments of internal medicine have been registered and evaluated. The aim of the presented part of the study was to look for evident differences in genotypes for polymorphic drug metabolizing enzymes between adverse drug reaction cases and controls. All cases found in the local area – Jena and Weimar – were genotyped for N-acetyl-transferase 2 (NAT2), cytochrom P450 (CYP) 2D6 and 2C19 in comparison to a control population of the same region. The investigation on genotype was carried out for about 2 years (2000–2002). 254 blood samples from patients of the ADR study were analyzed. The genotype of drug metabolizing enzymes was determined by means of polymerase chain reaction using allel specific primers or restriction enzyme analysis. Within all ADRs cases genotyped, no exceptional frequencies for slow acetylators or poor metabolizers (PM) of CYP2D6 or CYP2C19 were found. About 65% of the individuals with ADR genotypically displayed a slow acetylator state. 6.3% PM for CYP2D6, including CYP2D6*3, *4 and *6 alleles, and 2.0% PM frequency for CYP2C19 (*2) have been found in ADR cases. A direct connection between PM genotype and the ADR observed may be assumed only in few of them. Further investigations on genotype and ADR-associated drugs require a much larger sample of patients to obtain more data allowing to focus an association on specific drugs, ADR and polymorphisms genotype of drug metabolizing enzymes might be useful.     

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.     

A case report of a poor metabolizer of CYP2D6 presented with unusual responses to nortriptyline medication

We present a case with decreased metabolic activity of CYP2D6, a cytochrome P450 enzyme catalyzing the metabolism of nortriptyline (NT). Conventional dosage regimen led to toxic plasma concentration of NT and adverse effects such as dry mouth, constipation, and dizziness in this case with genotype CYP2D6*5/*10B. This case suggests the clinical usefulness of pharmacogenetic testing in individualized dosage adjustments of NT.     

CYP1A1、CYP2D6基因多态性对白血病发生的影响

目的 分析细胞色素P450 CYP1A1和CYP2D6的多态性基因型在湖南地区白血病患者和健康人群中的分布及其对白血病发生的影响.方法 采用PCR及PCR-RFLP技术分析多态性基因型频率.结果 CYP1A1和CYP2D6基因的野生型、杂合突变型及纯合突变型的分布频率在急性淋巴细胞性白血病、急性非淋巴细胞性白血病、慢性粒细胞性白血病患者组与健康对照组之间无显著性差异;携带一个突变等位基因型的个体患白血病的风险与相应野生型携带者比较均无显著性差异;急性非淋巴细胞性白血病患者组的CYP1A1杂合突变型与CYP2D6杂合突变型的联合基因型频率高于健康对照组.结论 单独的CYP1A1或CYP2D6基因的多态性变异与白血病易感性不相关;CYP1A1杂合突变与CYP2D6杂合突变的联合基因型增加患急性非淋巴细胞性白血病的风险.     

Prevalence of MDR1 C3435T and CYP2B6 G516T polymorphisms among HIV-1 infected South African patients

Data on genetic polymorphisms associated with response to anti-HIV drugs has accumulated over the years. Information on how polymorphisms influence drug metabolism and transport to target sites is important in guiding dosage or selection of appropriate alternative therapies. This study determined the frequency of MDR1 C3435T and CYP2B6 G516T polymorphisms associated with the transport and metabolism of efavirenz and nevirapine, in a population of South African HIV infected patients. In addition, association of polymorphisms with immunologic and virologic factors was investigated. A 207bp of MDR1 exon 26 and a 161bp of CYP2B6 exon 4 were obtained from patients by polymerase chain reaction. Analysis of population-based sequences of MDR1 revealed a frequency of 89% and 11% of C and T alleles respectively (n=197; X^{2} = 0.974; p=0.324). Restriction fragment length polymorphism (RFLP) analysis of the CYP2B6 gene revealed a prevalence of 9.5% of GG, 78.4% of GT and 12.1% of TT genotype (n= 199; X^{2} = 65.204; p=0.00). There was no significant difference between immune recovery and decline in viral load (n=53), with genotype after repeated calculations of analysis of variance (ANOVA).