CYP2C19 haplotypes in Koreans as a marker of enzyme activity evaluated with omeprazole

Background and objective:  CYP2C19 is clinically important in Korea because of the relatively high incidence of poor metabolizers in the population. To fully understand the genetic mechanism of the CYP2C19 defect in poor metabolizers, all variants need to be studied simultaneously. The aim of this study was to investigate the usefulness of CYP2C19 haplotypes as a marker of CYP2C19 enzyme activity in Koreans.
Methods:  We analysed the single nucleotide polymorphisms and haplotypes of the CYP2C19 gene in 150 healthy Koreans and found three major (frequency > 0·1) haplotypes (H1, H2 and H3). One oral dose of 40 mg omeprazole (Losec^®) was administered to 30 subjects grouped as H1/H1, H2/H2, H1/H2, H1/H3 and H2/H3. The pharmacokinetics of omeprazole and its metabolites, 5-hydroxyomeprazole and omeprazole sulphone, in those groups was analysed.
Results and discussion:  The area under the plasma concentration–time curve (AUC_0→∞) and elimination half-life ( T _1/2) of omeprazole were significantly greater in the H2/H2 and H2/H3 groups than in the H1/H1 group ( P  <   0·05), whereas the metabolic ratios of omeprazole to 5-hydroxyomeprazole were also markedly higher.
Conclusion:  Although a specific SNP of CYP2C19 may be predictive of enzyme activity, haplotyping is more reliable for identifying poor metabolizers in populations with variant alleles other than CYP2C19*2 and *3 alleles.     

CYP2C9 and CYP2C19 genetic polymorphisms: frequencies in the south Indian population

The aim of the study was to establish the frequencies of CYP2C9*1, *2, *3 and CYP2C19*1, *2 and *3 in the south Indian population and to compare them with the inter-racial distribution of the CYP2C9 and CYP2C19 genetic polymorphisms. Genotyping analyses of CYP2C9 and CYP2C19 were conducted in unrelated, healthy volunteers from the three south Indian states of Andhra Pradesh, Karnataka and Kerala, by the polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP). The allele frequencies of the populations of these three states were then pooled with our previous genotyping data of Tamilians (also in south India), to arrive at the distribution of CYP2C9 and CYP2C19 alleles in the south Indian population. Frequencies of CYP2C9 and CYP2C19 alleles and genotypes among various populations were compared using the two-tailed Fisher's exact test. The frequencies of CYP2C9*1, *2 and *3 in the south Indian population were 0.88 (95% CI 0.85-0.91), 0.04 (95% CI 0.02-0.06) and 0.08 (95% CI 0.06-0.11), respectively. The frequencies of CYP2C9 genotypes *1/*1, *1/*2, *1/*3, *2/*2, *2/*3 and *3/*3 were 0.78 (95% CI 0.74-0.82), 0.05 (95% CI 0.03-0.07), 0.15 (95% CI 0.12-0.18), 0.01 (95% CI 0.0-0.02), 0.01 (95% CI 0.0-0.02) and 0.0, respectively. CYP2C19*1, *2 and *3 frequencies were 0.64 (95% CI 0.60-0.68), 0.35 (95% CI 0.31-0.39) and 0.01 (95% CI 0.0-0.03), respectively. As a result of a significant heterogeneity, the data on CYP2C19 genotype frequencies were not pooled. The frequency of CYP2C9*2 mutant alleles in south Indians was higher than in Chinese and Caucasians, while CYP2C9*3 was similar to Caucasians. CYP2C19*2 was higher than in other major populations reported so far. The relatively high CYP2C19 poor-metabolizer genotype frequency of 12.6% indicates that over 28 million south Indians are poor metabolizers of CYP2C19 substrates.     

细胞色素酶CYP2C19代谢对沙利度胺体外抗骨髓瘤作用的影响

目的 研究人肝微粒体代谢对沙利度胺体外抗骨髓瘤作用的影响,并探讨细胞色素酶CYP2C19在其中的作用.方法 以沙利度胺或与人肝微粒体在体外孵育后分别处理多发性骨髓瘤(MM)细胞株U266、NCI-H929、RPMI 8226、LP-1和CZ-1细胞,采用MTT法检测细胞活力,流式细胞术测定细胞周期和细胞凋亡.结果 沙利度胺对MM细胞活力无明显抑制作用,10、50和100μg/ml沙利度胺处理5株MM细胞后的细胞活力分别为96.2%～103.7%、96.3%～103.7%和97.9%～106.5%,与对照组比较差异无统计学意义(P>0.05).但与人肝微粒体孵育后,沙利度胺明显抑制MM细胞活力,且该作用呈剂量依赖性.10、50和100μg/ml沙利度胺与人肝微粒体共孵育后对5株MM细胞活力抑制率分别为12.2%～22.9%、25.9%～36.4%和34.9%～46.3%,与对照组比较差异均具有统计学意义(P<0.05).100μg/ml沙利度胺与人肝微粒体孵育后,5株MM细胞凋亡的比例增加达18.5%～32.5%.在孵育体系中加入CYP2C19特异性抑制剂奥美拉唑后,沙利度胺与人肝微粒体孵育后对MM细胞活力的抑制作用减弱,5 μmol/L和10μmol/L奥美拉唑对100μg/ml沙利度胺经肝微粒体孵育后抑制细胞活力的逆转率分别为7.5%～21.9%和19.1%～38.3%,差异有统计学意义(P<0.05).结论 沙利度胺的体外抗骨髓瘤作用需要人肝脏代谢,细胞色素酶系中的CYP2C19参与了这一过程.     

Stereospecific analysis of omeprazole supports artemisinin as a potent inducer of CYP2C19

The purpose of the study was to determine the enantiomer pharmacokinetics of omeprazole and 5-hydroxy-omeprazole before and after administration of the antimalarial artemisinin to confirm artemisinin's ability to induce CYP2C19. Nine healthy male Vietnamese subjects were given a single 20 mg dose of omeprazole orally 1 week before (day - 7) artemisinin administration. Artemisinin was then given orally (500 mg) for 7 days (days 1-7). On days 1 and 7, a single 20 mg dose of omeprazole was coadministered with artemisinin. After a washout period of 6 days, a single 20 mg dose of omeprazole was again administered together with a single 500 mg of artemisinin (day 14). Stereoselective pharmacokinetics of omeprazole and 5-hydroxyomeprazole was determined on days of omeprazole administration. Seven days of artemisinin administration significantly decreased the AUC of both omeprazole enantiomers (day 7), compared with day 1 (P < 0.001). All values were normalized after the washout period. Artemisinin increased the AUC ratio of R-5-hydroxyomeprazole/R-omeprazole significantly (P < 0.01) on day 7. The AUC ratio of omeprazole sulphone/S-omeprazole did not differ between study days. Artemisinin decreased the AUC of S-omeprazole to the same extent as that of R-omeprazole in extensive CYP2C19 metabolizers. suggesting that artemisinin induces a different enzyme in addition to CYP2C19. These results support and strengthen earlier findings that artemisinin induces CYP2C19 as well as at least one enzyme other than CYP3A4.     

CYP2C10基因多态性对奥美拉唑治疗十二指肠溃疡的影响

目的 探讨奥美拉唑治疗十二指肠溃疡合并幽门螺旋菌感染的疗效及其与CYP2C19基因多态性的关系.方法 应用奥美拉唑+阿莫西林+克拉霉素三联用药1周后单用奥美拉唑抑酸3周的方案治疗65例经胃镜证实的十二指肠溃疡合并幽门螺旋菌( Hpylori)感染患者.记录治疗前和用药后症状的变化,并于治疗结束时复查胃镜.患者CYP2C19的基因型检测采用聚合酶链式反应-限制性片段长度多态性(PCR-RFLP)分析方法.结果 65例十二指肠溃疡患者中,24例为纯合子强代谢者,31例为杂合子强代谢者,10例为弱代谢者.纯合子强代谢组、杂合子强代谢组和弱代谢组有效率分别为75.0％、90.3％和100％,纯合子强代谢组的治愈率显著低于弱代谢组(P＜0.05).弱代谢型组患者的Hpylori清除率显著高于纯合子强代谢型和杂合子强代谢型(P＜0.05).结论 CYP2C19基因多态性与奥美拉唑治疗十二指肠溃疡合并幽门螺旋菌感染的疗效密切相关.CYP2C19基因分型检测是临床治疗酸相关性疾病中的一个重要的工具.     

Distribution of CYP2C19*17 allele and genotypes in an Indian population

What is known and Objective: CYP2C19*17 allele increases the metabolic activity of CYP2C19 resulting in decreased therapeutic levels of CYP2C19 substrates. There exist inter‐ethnic differences in the distribution of this allele. The present study was aimed at establishing the allele and genotype frequencies of CYP2C19*17 in a South Indian Tamilian population. Furthermore, we describe the haplotype structure of the three common variant alleles of CYP2C19 in the Tamilian population. Methods: Two hundred and six subjects of South Indian Tamilian origin were genotyped for CYP2C19*17 allele by nested polymerase chain reaction and restriction fragment length polymorphism. A subset of 87 subjects were also genotyped for CYP2C19*2 and CYP2C19*3 alleles. After ascertaining linkage disequilibrium (LD), haplotypes were constructed. Allele and genotype frequencies, LD pattern and haplotype frequency were compared with those of the HapMap populations. Results and Discussion: The CYP2C19*17 allele frequency in the Tamilian population (n = 206) was found to be 19·2% (95% CI: 15·4 – 20·3). The CYP2C19*2 allele frequency (n = 87) was found to be 40·2% (95% CI: 32·9 – 47·5), whereas the CYP2C19*3 allele was not detected in the study subjects (n = 97). The high frequency of the CYP2C19*17 allele in the study population has resulted in a revision of frequencies for CYP2C19*1/*2 (31·0%) and CYP2C19*1/*1 (16·1%) genotypes in the Tamilian population. We also observed significant differences in haplotype structure and frequencies of these variant alleles in the HapMap population compared to Tamilian population. What is new and conclusion: CYP2C19*17 allele is present at high frequency in the Tamilian population. This study also demonstrates the need for reassessment of wild‐type allele frequencies in view of CYP2C19*17 allele. The estimated high frequency of CYP2C19*17 allele will aid in genotype–phenotype association studies in the Tamilian population. Further genotype–phenotype association studies are required to evaluate the clinical utility of this allele in South Indians.     

Assessment of CYP2C19 genetic polymorphisms in a Korean population using a simultaneous multiplex pyrosequencing method to simultaneously detect the CYP2C19*2, CYP2C19*3, and CYP2C19*17 alleles

Background and objective: CYP2C19 is a drug‐metabolizing enzyme showing various genetic polymorphisms that may cause marked interindividual and interethnic variability in the disposition of its substrates. We assessed CYP2C19 genetic polymorphisms in a Korean population using a newly developed multiplex pyrosequencing method. Method: A multiplex pyrosequencing method to simultaneously detect CYP2C19*2, *3, and *17 alleles was designed. We established the frequency of these CYP2C19 alleles in 271 Korean subjects using the multiplex pyrosequencing method. Results: The results showed 100% concordance between single and multiplex pyrosequencing methods. We also validated the polymorphisms identified by pyrosequencing with direct sequencing method. The allele frequencies of CYP2C19*2, CYP2C19*3, and CYP2C19*17 were 0·284, 0·101 and 0·015 respectively. These frequencies are similar to that reported for other Asian populations including Japanese and Chinese but different from that of Caucasians and Africans. Conclusions: The multiplex pyrosequencing method to detect CYP2C19*2, CYP2C19*3, and CYP2C19*17 concurrently, seems to be a rapid and reliable genotyping method for the detection of important CYP2C19 genetic polymorphisms. Similar to studies conducted on other Asian populations, this study reported that in the Korean population tested, the CYP2C19*2 and CYP2C19*3 alleles were relatively frequently found, whereas the frequency of CYP2C19*17 was very low.     

Genetic polymorphisms of drug-metabolizing enzymes CYP2D6, CYP2C9, CYP2C19 and CYP3A5 in the Greek population

The aim of the present study was to determine the prevalence of the most common allelic variants of the polymorphic cytochrome P450 (CYP) enzymes CYP2D6, CYP2C9, CYP2C19 and CYP3A5 and to predict the genotype frequency for each polymorphism in the Greek population. DNA isolated from peripheral blood samples derived from 283 non-related Greek ethnic subjects was used to determine the frequency of CYP2D6*3, CYP2D6*4, CYP2C9*2, CYP2C9*3 and CYP3A5*3 allelic variants by the polymerase chain reaction (PCR)-restriction fragment length polymorphism method, CYP2C19*2 and CYP2C19*3 with allelic specific amplification (PCR-ASA), and CYP2D6*2 (gene duplications) by long PCR analysis. The allelic frequencies (out of a total of 566 alleles) for CYP2D6*3 and CYP2D6*4, were 2.3% and 17.8%, respectively, while gene duplications (CYP2D6*2) were found in 7.4% of the subjects tested. For CYP2C9*2 and CYP2C9*3 polymorphisms the allelic frequencies were 12.9% and 8.13% respectively. For CYP2C19, the *2 polymorphism was present at an allelic frequency of 13.1%, while no subjects were found carrying the CYP2C19*3 allele. Finally, the CYP3A5*3 allele was abundantly present in the Greek population with an allelic frequency of 94.4%. Overall our results show that the frequencies of the common defective allelic variants of CYP2C9, CYP2C19 and CYP3A5 in Greek subjects are similar to those reported for several other Caucasian populations. Finally, a high prevalence of CYP2D6 gene duplication among Greeks was found, a finding that strengthens the idea that a South/North gradient exists in the occurrence of CYP2D6 ultrarapid metabolizers in European populations.     

Effects of CYP2C19 genetic polymorphism on the pharmacokinetics and pharmacodynamics of omeprazole in Chinese people

BACKGROUND: To investigate whether the pharmacodynamics and pharmacokinetics of omeprazole (OPZ) are dependent of the CYP2C19 genotype status in Chinese people. METHODS: Eighteen healthy subjects were voluntary to participate in the study, whose CYP2C19 genotype status were determined by polymerase chain reaction-restriction fragment length polymorphism method. There were six homozygous extensive metabolizers, six heterozygous extensive metabolizers and six poor metabolizers (PMs). All subjects were Helicobacter pylori-negative, determined by serology method and (13)C-urea breath test. After d1 and d8 orally received OPZ 20 mg once daily in the morning, intragastric pH values were monitored for 24 h by Digitrapper pH. Meanwhile, blood samples were collected at various time-points until 24 h after administration. The serum concentrations of OPZ were measured by liquid chromatography. RESULTS: After single or repeated doses, the PMs showed a significantly higher mean area under the serum concentration-time curves (AUC) values than that observed in the homozygous extensive metabolizers or the heterozygous extensive metabolizers, with a relative ratio of 1.0 : 1.1 : 4.2 and 1.0 : 1.3 : 3.3 (homozygous extensive metabolizers:heterozygous extensive metabolizers:poor metabolizers), respectively. After a single dose of OPZ, significant differences in intragastric pH median, pH > 3 holding time and pH > 4 holding time were observed among the three groups. After repeated doses, the PMs showed a significantly higher intragastric pH values than that observed in the homozygous extensive metabolizers or the heterozygous extensive metabolizers. CONCLUSION: The pharmacodynamic effects of OPZ and its pharmacokinetics depend on the CYP2C19 genotype status in Chinese people.     

细胞色素酶CYP2C19介导的沙利度胺体外抗血管生成作用研究

本研究探讨人肝细胞微粒体代谢系统对治疗多发性骨髓瘤的沙利度胺体外抗血管生成的影响及细胞色素酶CYP2C19在其中的作用。采用沙利度胺原药或与人肝细胞微粒体在体外共孵育后用MTY法检测人脐带静脉内皮细胞（human umbilical cord vein endothelial cells,hUCVEC）增殖活力,用流式细胞术测定hUVCEC细胞周期和细胞凋亡,以改良的Boyden小室法检测hUCVEC细胞迁移力,以体外小管形成实验检测hUCVEC分化。结果表明：沙利度胺原药对hUCVEC活力无明显抑制作用,细胞凋亡比例也无明显增加,轻度影响细胞迁移,无抗小管形成作用;当与人肝细胞微粒体共孵育后hUCVEC增殖活力明显受抑。100μg／ml沙利度胺与肝细胞微粒体共孵育后hUCVEC增殖活力的抑制率达（11．7±3．9）％,凋亡细胞增加达27．2％,明显下调细胞迁移力并抑制体外小管形成。在共孵育体系中加入CYP2C19特异性抑制剂奥美拉唑,可减弱沙利度胺抑制hUCVEC增殖活力和诱导凋亡的作用,减低细胞迁移力和部分逆转抗小管形成的作用。结论：沙利度胺的体外抗血管生成作用依赖于人细胞微粒体的作用,细胞色素酶系中的CYP2C19可能参与了这一过程。     

CYP2C19基因多态性在江苏及其周边地区汉族人群的调查研究

目的探讨CYP2C19基因型在江苏及其周边地区汉族人群中基因多态性的分布。方法取81名汉族健康人的外周血,应用聚合酶链反应(PCR)-限制性片段长度多态性分析(RFLP)CYP2C19等位基因分型。结果在81名检测标本中,CYP2C19纯合子强代谢型、杂合子强代谢型和弱代谢型的发生率分别为38.3%、45.7%和16.0%。结论江苏及其周边地区汉族人群存在CYP2C19的基因多态性,其弱代谢型的发生率与中国汉族人总体发生率基本一致。     

Evaluation of the relationship between polymorphisms in CYP2C19 and the single‐dose pharmacokinetics of omeprazole in healthy Chinese volunteers: A multicenter study

The aim of this study was to evaluate the relationship between polymorphisms in CYP2C19 and the single‐dose pharmacokinetics (PKs) of omeprazole in healthy Chinese volunteers. A 20 mg single dose of omeprazole (Losec) enteric‐coated capsules or tablets was orally administered to 656 healthy subjects from eight subcenters. The polymorphic alleles of CYP2C19*2, *3, and *17 were determined by Sanger sequencing and Agena mass array. Plasma concentrations of omeprazole were determined by high‐performance liquid‐chromatography tandem mass spectrometry. PK parameters of area under the concentration versus time curve (AUC)_0‐t, AUC from zero to infinity (AUC_0‐∞), maximum plasma concentration (C_max), and terminal half‐life (t_1/2) were significantly influenced by CYP2C19 phenotype (all p < 0.001) and diplotype (all p < 0.001), and the same results were obtained in the subgroup analysis of the effects of diet and dosage form. The polymorphisms of CYP2C19*2(rs4244285; all PK parameters p < 0.001) and *3(rs4986893; p _Cmax = 0.020, and the p values of other PK parameters were less than 0.001) were significantly associated with the PKs of omeprazole. For CYP2C19*17 (rs12248560), only t_1/2 showed a significant correlation (p = 0.032), whereas other PK parameters did not. The present study demonstrated that the Pks of omeprazole is greatly influenced by CYP2C19.     

重庆地区汉族人群CYP2C19基因多态性分布与不同种族间比较

摘要：目的：了解重庆地区汉族人群CYP2C19基因多态性分布,比较不同种族间CYP2C19代谢型的分布。 方法：用基因芯片法检测140例重庆地区汉族健康人群CYP2C19基因多态性,并比较分析不同种族间的CYP2C19代谢型分布。 结果：在140例重庆地区汉族人群中,*1/*1基因型（636GG,681GG）62例（44.3%）,*1/*2基因型（636GG,681GA）57例(40.7%)〖JP〗,*1/*3基因型（636GA,681GG）8例（5.7%）,*2/*2 基因型（636GG,681AA）10例（7.1%）,*3/*3基因型（636AA,681GG）0例,*2/*3基因型（636GA,681GA）3例（2.1%）;快代谢型62例（44.3 %）,中代谢型65例（46.4%）,慢代谢型13例（9.3 %）。CYP2C19代谢型（快、中、慢代谢型）与美洲印第安人、高加索血统种人、黑白混血人种分布比较差异有统计学意义（χ²分别为46.78, 24.45,12.29,P均<0.05）,与非洲人差异无统计学意义（χ²=3.21,P＞0.05）。 结论: 重庆地区汉族人群CYP2C19位点存在基因多态性,与其他种族比较,代谢型分布有差异。     

黄石地区76例氯吡格雷治疗患者 CYP 2C19不同代谢表型的分布

目的：探讨湖北黄石地区氯吡格雷治疗患者 CYP2C19不同代谢表型的分布。方法取76例心内科住院氯吡格雷治疗患者的外周血,采用基因芯片方法对 CYP2C19基因进行分型,了解其代谢表型的分布,并与文献报道的中国正常汉族人群进行比较。结果在76例检测标本中检测出 CYP2C19的3种代谢表型,快代谢型、中间代谢型以及慢代谢型,所占比例分别为39．47％、44．74％和15．79％。与中国健康汉族人总体比例基本一致。结论湖北黄石地区氯吡格雷治疗患者的临床个体化用药方案可以中国汉族健康人群的个体化用药方案为参考依据。     

Differences in genotype and allele frequency distributions of polymorphic drug metabolizing enzymes CYP2C19 and CYP2D6 in mainland Chinese Mongolian, Hui and Han populations

What is known and Objective: Cytochrome P450 2C19 (CYP2C19) and CYP2D6 are important xenobiotic metabolic enzymes and both show considerable genetic variability between Orientals and Caucasians. There are known marked heterogeneity in susceptibility to various cancers and hypertension among Chinese Mongolian, Hui and Han ethnic groups, but the molecular mechanisms are unknown. Our objective was to investigate the patterns of distribution of CYP2C19 and CYP2D6 polymorphisms among healthy Chinese subjects to determine whether any observed inter‐ethnic variability might be worth further investigation as possible contributors to the known differences in disease prevalence. Methods: Blood samples were collected from 454 unrelated Chinese healthy subjects (214 Han, 111 Hui, 129 Mongolian) for genotyping analysis. The single nucleotide polymorphisms (SNPs) CYP2C19*2 (681G>A in exon 5), CYP2C19*3 (636G>A in exon 4) and CYP2D6*10 (188C>T in exon 1) were determined by the polymerase chain reaction–restriction fragment length polymorphism (PCR‐RFLP) method. Results and Discussion: Significantly higher frequencies of the CYP2C19 poor metabolic genotypes were observed in Chinese Han (18·7%), Chinese Hui (25·0%) and Chinese Mongolian (10·9%) subjects than has been reported for Caucasians (1·7–3·0%, P < 0·01). The prevalent defective allele CYP2C19*2 occurred more frequently in both Chinese Hui (32·4%) and Han (29·7%) than in Chinese Mongolian (18·2%, P < 0·01) subjects. The CYP2C19*2 and CYP2C19*3 defective alleles were significantly more frequent in Chinese Han and Chinese Hui ethnic groups than have been reported for Caucasians (11·1–16·3% and 0–0·2%, P < 0·01). CYP2D6*1/*10 heterozygotes and CYP2D6*10/*10 homozygotes were observed more frequently in Chinese Han (43·1% and 27·2%), Hui (40·6% and 30·7%) and Mongolian subjects (31·3% and 9·6%, both P < 0·01) than have been reported for Caucasians (5·5% and 0·3%, P < 0·01). In Chinese Mongolians, the CYP2D6*10 allele occurred at a frequency (25·2%, P < 0·01) intermediate between those reported for Caucasians and the other two Chinese ethnic populations. What is new and Conclusions: This is first report of interethnic differences in frequencies of functional CYP2C19 and CYP2D6 genes among Chinese Mongolian, Hui and Han populations. These differences may be important in explaining reported inter‐ethnic differences in disease prevalence and response to drugs.     

广东东莞地区心血管疾病患者CYP2C19基因多态性分析

目的研究广东东莞地区心血管病患者CYP2C19基因的多态性分布。方法选取心内科心血管疾病患者1 662例,抽取外周血并提取基因组DNA,用PCR技术结合基因芯片技术检测患者的CYP2C19基因型。对年龄45岁和年龄≥45岁冠心病患者CYP2C19等位基因频率和代谢表型频率进行比较。结果在1 662例患者中,CYP2C19代谢型713例(42.90%),中间代谢型740例(44.52%),慢代谢209例(12.58%)。CYP2C19*1、CYP2C19*2、CYP2C19*3等位基因频率分别为65.16%、30.08%、4.75%。45岁组检出快代谢型104例(40.00%),中间代谢型104例(45.38%),慢代谢型38例(14.62%)。≥45岁冠心病组检出快代谢型609例(43.44%),中间代谢型622例(44.37%),慢代谢171例(12.20%)。45岁与≥45岁组各基因型的比例比较,差异无统计学意义(P0.05)。结论通过检测CYP2C19基因型确定患者遗传特征,可以评估其氯吡格雷抵抗风险,为患者制订个体化的抗血小板治疗方案。