新疆维吾尔族和哈萨克族健康人群CYP2C9和VKORC1基因多态性研究

目的：了解细胞色素P450（CYP）2C9、维生素K环氧化还原酶复合体1（VKORC1）基因单核苷酸多态性在新疆维吾尔族和哈萨克族健康人群中的频率分布及与其他不同民族之间的差异,为新疆维吾尔族和哈萨克族人群实施华法林个体化用药剂量提供理论依据。方法：采用BaiO华法林敏感性基因检测试剂盒的芯片检测技术对506位新疆维吾尔族和哈萨克族健康者的CYP2C9＊2和CYP2C9＊3位点以及VKORCI（-1639A/G和1173T/C）位点基因多态性进行检测,统计其等位基因和基因型频率,并与国外多个民族的这两个基因多态性分布进行比较。结果：506份样本中共检测到CYP2C9的3种等位基因CYP2C9＊1、CYP2C9＊2和CYP2C9＊3,等位基因频率分别为89.6%、2.8%和7.6%;5种等位基因型分别为CYP2C9＊1/＊1,CYP2C9＊1/＊2,CYP2C9＊1/＊3,CYP2C9＊2/＊3和CYP2C9＊3/＊3。VKORC1-1639A/G检测出两种等位基因A和G,其频率分别为63.8%和36.2%;三种等位基因型AA（41.7%）、AG（44.3%）和GG（14%）的频率分别与1173T/C的TT、TC和CC型完全相同。结论：新疆维吾尔族和哈萨克族人群CYP2C9和VKORC1存在明显的基因多态性,其分布与中国汉族等亚洲人群以及欧美人群均存在较大差异。     

中国汉族和维吾尔族药物代谢酶CYP3A4、CYP2C9、CYP2C19、CYP2D6基因多态性分析

目的对中国汉族、维吾尔族健康人群CYP3A4、CYP2C9、CYP2C19、CYP2D6进行基因多态性分析,并对汉族和维吾尔族人群等位基因频率和基因型频率进行比较。方法聚合酶链反应一限制性片段长度多态性(PCR-RFLP)法对CYP3A4、CYP2C9、CYP2C19、CYP2D6进行分型。结果汉族、维吾尔族健康人群CYP3A4*5等位基因频率为0,CYP3A4*18等位基因频率分别为0.183 8、0.140 2;CYP2C9*2等位基因频率分别为0.011 0、0.095 8,CYP2C9*13等位基因频率分别为0、0.002 3;CYP2C19*2等位基因频率分别为0.386 0、0.324 8,CYP2C19*3等位基因频率分别为0.051 5、0.021 0;CYP2D6*10等位基因频率分别为0.573 5、0.224 3。结论本研究在汉族、维吾尔族健康人群中未发现CYP3A4*5等位基因。汉族、维吾尔族健康人群CYP3A4*18、CYP2C9*13、CYP2C19*2、CYP2C19*3等位基因频率差异均无统计学意义。维吾尔族健康人群CYP2C9*2等位基因频率远高于汉族(P<0.01);CYP2D6*10等位基因频率远低于汉族(P<0.01),存在民族差异。     

中国汉族和回族药物代谢酶细胞色素P450(CYP)3A4、CYP2C9、CYP2C19及CYP2D6基因多态性分析

目的对中国汉族、回族健康人群细胞色素P450(CYP)3A4、CYP2C9、CYP2C19及CYP2D6进行基因多态性分析,比较汉族和回族健康人群基因表型和基因频率分布。方法多聚酶链反应-限制性片段长度多态性(PCR-RFLP)法,对300名志愿者的几种基因进行分型。结果汉族、回族CYP3A4*5等位基因频率均为0,CYP3A4*18等位基因频率分别为0.18,0.19;汉族、回族CYP2C9*2等位基因频率分别为0.01,0.05;CYP2C9*13等位基因频率均为0;汉族、回族CYP2C19*2等位基因频率分别为0.39,0.50;CYP2C19*3等位基因频率分别为0.05,0.05;汉族、回族CYP2D6*10等位基因频率分别为0.57,0.39。结论汉族、回族健康人群的CYP3A4*18、CYP2C9*2、CYP2C19*2、CYP2C19*3均没有显著性差异;在汉族、回族健康人群中未发现CYP3A4*5和CYP2C9*13突变;汉族、回族CYP2D6*10等位基因频率有显著性差异(P<0.01);回族人群CYP2D6中速代谢型(*10/*10)频率为13.4%,明显低于汉族的33.1%(P<0.01)。     

新疆汉族健康人群维生素K环氧化物还原酶亚单位1启动子区1639A/G基因多态性研究

目的了解VKORC1-1639A/G基因多态性在新疆汉族健康人群中的分布及其与其他不同民族之间的差异。方法采用PCR-RFLP技术对205名乌鲁木齐地区汉族体检健康人群VKORC1-1639A/G基因多态性进行检测,计算其基因型和等位基因频率,并与国外多个民族VKORC1-1639A/G基因多态性分布进行比较。结果新疆汉族健康人群中共检测到2种等位基因:A和G。等位基因频率分别为87%和13%。新疆汉族健康人群VKORC1-1639A/G基因多态性共检测到3种基因型,以AA基因型常见,基因型频率74%。其次是AG基因型,基因型频率分别为26%。GG基因型的个体仅检测到1例,基因型频率小于1。结论新疆汉族VKORC1-1639A/G基因多态性以A等位基因和AA基因型常见,新疆汉族VKORC1-1639A/G基因多态性与欧美人群相比存在较大差异。     

沙坦类药物代谢酶CYP2C9和受体AT1基因的遗传多态性在高血压患者中的分布特征

目的本研究旨在观察沙坦类药物代谢酶CYP2C9和反应受体AT1的遗传多态性在高血压患者中的分布特征。方法采用聚合酶链式反应-限制性片断长度多态性方法(PCR-RFLP)对高血压患者进行CYP2C9和血管紧张素AT1受体基因型分析。结果对120名高血压患者CYP2C9和血管紧张素AT1受体进行基因型分析,发现高血压人群中CYP2C9*3的1 061位T等位基因和AT1受体突变1 166位C等位基因的分布频率分别为2.9%、8.0%,而这2个等位基因在中国正常人群的分布频率分别为1.5%、4.3%。结论高血压人群中CYP2C9*3的1061位T等位基因和AT1受体1 166位C等位基因的频率均高于正常人群。     

新疆维吾尔族患者CYP2C9和VKORC1基因多态性分布及不同种族间的比较

目的:为建立适合新疆维吾尔族患者的华法林个体化给药模型提供研究基础。方法:检测200例新疆维吾尔族患者中CYP2C9和VKORC1的基因型,并与世界不同种族人群基因型及等位基因频率进行比较。结果:新疆维吾尔族CYP2C9*1/*1基因型频率低于韩国、日本、美国及中国汉族,高于土耳其;*1/*2杂合突变型频率低于土耳其、瑞典、英国,高于韩国、日本及中国汉族;*1/*3杂合突变型频率高于日本、韩国、中国汉族、英国、美国;*3/*3基因频率高于上述人群(P<0.05)。新疆维吾尔族*1等位基因频率低于中国汉族、日本、韩国、美国,高于土耳其;*2等位基因高于中国汉族、日本、韩国,低于土耳其、瑞典、英国;*3等位基因高于中国汉族、日本、韩国、瑞典、英国和美国(P<0.05)。VKORC1-1639AA型频率高于美国、瑞典、英国,低于新加坡、日本、中国台湾、中国汉族;AG型频率高于新加坡、日本、中国台湾、中国汉族;GG型频率高于新加坡、日本、中国台湾、中国汉族,低于美国、瑞典、英国(P<0.05)。新疆维吾尔族A型等位基因频率低于中国汉族、中国台湾、日本、新加坡,高于美国、瑞典和英国;G型等位基因高于中国汉族、中国台湾、日本、新加坡,低于美国、瑞典、英国(P<0.05)。结论:新疆维吾尔族患者CYP2C9和VKORC1基因多态性分布与亚洲及欧美人群均存在明显差异。     

河南地区汉族人群药物代谢酶CYP2C19，NAT2和TPMT基因多态性分析(英文)

目的：了解细胞色素P450(cytochromes P450,CYP)2C19,N-乙酰基转移酶2(arylamine N- acetyltransferase 2,NAT2)和硫嘌呤甲基转移酶(thiopurine S-methyltransferase,TPMT)基因常见的遗传多态性在河南地区汉族人群中的分布及其频率。方法：应用聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)对210名河南地区汉族人群的CYP2C19突变基因(*2和*3)、NAT2突变基因(*6和*7)和TPMT突变基因(*3A,*3B和*3C)进行检测。用聚合酶链反应-等位基因特异性扩增(PCR-ASA)对NAT2突变基因(*5)和TPMT突变基因(*2)进行检测。结果：CYP2C19*2和*3等位基因分布频率分别为34．76%和6．4%,同时携带2个等位突变基因的慢基因型频率占14．8%。NAT2*4(wt),*5(341C),*6(590A)和*7(857A)等位基因分布频率分别为59．1%,4．1%,26．4%和9．5%,慢基因型分布频率占19．5%。TPMT*3C等位基因分布频率为1．2%,未发现TPMT*2,TPMT*3A或TPMT*3B。结论：CYP2C19,NAT2和TPMT基因常见的遗传多态性在汉族人群中的分布及其频率与白人存在明显差异,这将有助于我国汉族人群临床药动学研究和给药剂量的确定。     

161例服用华法林的房颤患者CYP2 C19*2基因多态性研究

目的：了解161例服用华法林房颤患者CYP2C19*2（681G／A）基因多态性及不同人群的基因频率分布差异。方法采用聚合酶链反应-限制性片段长度多态性（PCR-RFLP）技术,测定161例服用华法林的房颤患者CYP2C19*2（681G／A）基因型,并比较不同人群的基因分布差异。结果 CYP2C19*1及CYP2C19*2等位基因频率分别为63.04％和36.96％。 CYP2C19*1／*1、CYP2C19*1／*2及 CYP2C19*2／*2频率分别为40.4％,44.1％和15.5％。结论本研究人群CYP2C19*2等位基因频率分布与报道的汉族人群、日本、韩国人群相似;但显著高于高加索人群、美籍非州人群。     

细胞色素P450 3A4基因多态性与中国汉族女性乳腺癌易感性的相关性研究

目的 探讨细胞色素P450 3A4(CYP3A4)基因多态性与中国汉族女性乳腺癌易感性的相关性。方法 用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)的方法检测148例中国汉族女性乳腺癌患者及160例健康受试者的CYP3A4*1G多态性,分析2组CYP3A4*1G基因型及等位基因分布频率。结果 中国汉族女性乳腺癌患者和健康受试者CYP3A4*1G基因型分布均符合Hardy-Weinberg平衡。乳腺癌患者和健康受试者CYP3A4*1G等位基因频率分别为15.9%和22.2%(P<0.05),CYP3A4*1G基因型的分布频率在2组间差异有统计学意义(P<0.01)。结论 CYP3A4*1G多态性与中国汉族女性乳腺癌的易感性存在负相关性。     

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。     

Allele and genotype frequencies of CYP2C9 in a Korean population

AIMS: To determine the frequencies of the variant alleles and the genotypes of CYP2C9 in a Korean population. METHODS: Three hundred and fifty-eight healthy Korean subjects were studied. CYP2C9 alleles were detected by polymerase chain reaction-restriction fragment length polymorphism assays and direct sequencing assays. RESULTS: The allele frequencies were 0.934 for CYP2C9*1, 0.060 for CYP2C9*3 and 0.006 for CYP2C9*13. The CYP2C9*2,*4,*5 and *11 alleles were not detected. The frequencies of the CYP2C9*1/*1, *1/*3 and *1/*13 genotypes were 0.869, 0.120 and 0.011, respectively. CONCLUSION: The frequency of the CYP2C9*3 allele in the Korean population studied was significantly higher than reported elsewhere, and a novel allele, CYP2C9*13, was found at a frequency of 0.006 (95% confidence interval 0, 0.012). Only three genotypes of CYP2C9, CYP2C9*1/*1,*1/*3 and *1/*13 were observed in this Korean population.     

Allele and genotype frequencies of CYP2C9, CYP2C19 and CYP2D6 in an Italian population.

The polymorphic cytochrome P450 isoenzymes (CYPs) 2C9, 2C19 and 2D6 metabolise many important drugs, as well as other xenobiotics. Their polymorphism gives rise to important interindividual and interethnic variability in the metabolism and disposition of several therapeutic agents and may cause differences in the clinical response to these drugs. In this study, we determined the genotype profile of a random Italian population in order to compare the CYP2C9, CYP2C19 and CYP2D6 allele frequencies among Italians with previous findings in other Caucasian populations. Frequencies for the major CYP2C9, CYP2C19 and CYP2D6 mutated alleles and genotypes have been evaluated in 360 unrelated healthy Italian volunteers (210 males and 150 females, aged 19-52 years). Genotyping has been carried out on peripheral leukocytes DNA by molecular biology techniques (PCR, RFLP, long-PCR). CYP2C9, CYP2C19 and CYP2D6 allele and genotype frequencies resulted in equilibrium with the Hardy-Weinberg equation. One hundred and fourteen subjects (31.7%) carried one and 23 subjects (6.4%) carried two CYP2C9 mutated alleles. Sixty-eight (18.9%) volunteers were found to be heterozygous and six (1.7%) homozygous for the CYP2C19*2, while no CYP2C19*3 was detected in the evaluated population. Volunteers could be divided into four CYP2D6 genotypes groups: 192 subjects (53.3%) with no mutated alleles (homozygous extensive metabolisers, EM), 126 (35.0%) with one mutated allele (heterozygous EM), 12 (3.4%) with two mutated alleles (poor metabolisers, PM) and 30 (8.3%) with extracopies of a functional gene (ultrarapid metabolisers, UM). Frequencies of both CYP2C9 and CYP2C19 allelic variants, as well as CYP2D6 detrimental alleles, in Italian subjects were similar to those of other Caucasian populations. Conversely, the prevalence of CYP2D6 gene duplication among Italians resulted very high, confirming the higher frequency of CYP2D6 UM in the Mediterranean area compared to Northern Europe.     

Genetic polymorphisms of cytochrome P450 enzymes 2C9 and 2C19 in a healthy Iranian population

1. The genetically polymorphic cytochrome P450 enzymes 2C9 (CYP2C9) and 2C19 (CYP2C19) are involved in the metabolism and elimination of a number of widely used drugs. The polymorphisms give rise to substantial interindividual and interethnic variability in drug excretion rates and final serum concentrations. For this reason, therapeutic responses and adverse drug reactions may vary from one person to another. In the present study we determined CYP2C9 and CYP2C19 genotypes in a random Iranian population to compare allele frequencies with previous findings in other ethnic groups. 2. Allelic variants of CYP2C9 (*1/*2/*3) and CYP2C19 (*1/*2/*3) were determined in 200 unrelated healthy Iranian volunteers by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assays. 3. Fifteen subjects (7.5%) were homozygous for the CYP2C9*2 allele, whereas 21 individuals (10.5%) were heterozygous for this allele and 164 subjects (82%) had the wild-type allele (CYP2C9*1). No CYP2C9*3 was detected in the population sampled. Six subjects (3%) were homozygous for CYP2C19*2, whereas 44 individuals (22%) were heterozygous for this allele. In the remaining subjects (75%), no CYP2C19*2 was found. In addition, no CYP2C19*3 was detected in the population sampled. 4. Based on our data, the frequency of the CYP2C9*2 allelic variant in Iranians is similar to that in other Caucasian populations; however, the frequency of the CYP2C9*3 allele differed significantly (P < 0.05). Conversely, there was no difference in the frequency of CYP2C19 allelic variants between the present study and other studies evaluating this allele in Caucasian populations (P > 0.05).     

CYP2C9 genotypes and diclofenac metabolism in Spanish healthy volunteers

OBJECTIVE: This study analyzed the frequency of CYP2C9 variant alleles and evaluated the impact of CYP2C9 genotype on diclofenac metabolism in a Spanish population. METHODS: Diclofenac hydroxylation capacity was studied in a population of 102 healthy volunteers. After a single oral dose of 50 mg diclofenac the 0- to 8-h urinary concentrations of diclofenac and its main metabolites, 4'-hydroxy (OH), 3'-OH and 5-OH diclofenac were analyzed by high-performance liquid chromatography. CYP2C9 genotyping for the variant alleles CYP2C9*2 and *3 was carried out with PCR-RFLP. RESULTS: The frequencies of CYP2C9*1, *2, and *3 alleles were 0.74 (95%CI: 0.68-0.80), 0.16 (95%CI: 0.11-0.21) and 0.10 (95%CI: 0.06-0.15), respectively, among the 102 Spaniards studied. The diclofenac/4'-OH diclofenac urinary ratio, but not the diclofenac/3'-OH diclofenac and diclofenac/5-OH diclofenac ratios, was related to CYP2C9 genotype. The diclofenac/4'-OH ratio was significantly higher among subjects with CYP2C9*1/*3 (0.83+/-0.4, n=14, 95% CI for the difference: 0.02-0.4) and CYP2C9*2/*3 (1.10+/-0.5, n=4, 95% CI for the difference: 0.16-0.8) genotypes compared to CYP2C9*1/*1 (0.62+/-0.3, n=59) and approximately threefold higher (1.8) in the only subject homozygous for CYP2C9*3 variant. CONCLUSIONS: The frequencies of CYP2C9*1, *2, and *3 alleles in the Spanish population reported here were similar to those found in the previously studied white European populations, and different of the previously reported in another Spanish population. CYP2C9*3 allele seems to influence the 4'-hydroxylation of diclofenac, although there is a large overlapping in the urinary metabolic ratio between the genotype groups studied     

Genetic polymorphisms of drug-metabolizing phase I enzymes CYP3A4, CYP2C9, CYP2C19 and CYP2D6 in Han, Uighur, Hui and Mongolian Chinese populations

We randomly evaluated 672 unrelated, healthy Chinese volunteers (136 Han, 214 Uighur, 164 Hui and 158 Mongolian) to compare CYP3A4, CYP2C9, CYP2C19 and CYP2D6 allele frequencies. Genomic DNA was extracted from peripheral leukocytes and genotyped for CYP3A4*5, CYP3A4*18, CYP2C9*2, CYP2C9*13, CYP2C19*2, CYP2C19*3 and CYP2D6*10 by PCR-restriction fragment length polymorphism analysis (PCR-RFLP). Our results showed that there is no significant difference in the distribution of CYP2C19*3 and CYP3A4*18 genotypes in the Han, Uighur, Hui and Mongolian Chinese populations. The CYP2C9*13/*13 and CYP3A4*5 genotypes were not observed in any of the four Chinese populations. We found a higher incidence of the CYP2C9*2 allele in Uighur populations, compared to the Han, Hui and Mongolian populations. The incidence of the CYP2C19*2 allele in the Han population was not significantly different from that in the Uighur, Hui or Mongolian populations; however, the Uighur population showed significantly lower rates of this allele than the Hui and Mongolian populations, and the Mongolian population had a significantly lower incidence of this allele than the Hui population. There was no significant difference in the presence of the CYP2D6*10 allele in the Mongolian, Han or Hui populations. However, the Uighur population showed significantly lower rates of this allele than the other three populations. These findings provide basic genetic information for further pharmacogenomic investigations in the Chinese population.     

CYP2D6 genetic polymorphism in South Indian populations

This study aimed to determine the prevalence of genetic polymorphism in the CYP2D6 gene, which codes for the polymorphically expressed CYP2D6 drug-metabolizing enzyme. The common variants CYP2D6 *2, *3, *4, *5, *10, *14, and *17 were studied in the populations (n=447) of the four South Indian states namely Tamilnadu (TN), Kerala (Ker), Karnataka (Kar) and Andhra Pradesh (AP). Genetic polymorphisms were identified using polymerase chain reaction (PCR) and PCR-Restriction Fragment Length Polymorphism (PCR-RFLP) based methods. Differences in frequencies of CYP2D6 polymorphism between each South Indian state were statistically compared, and also the frequency of South Indian population as a whole in relation to other major populations. The CYP2D6*2 allele was the most frequent variant (34.8%), followed by the *10 allele (10.2%). The *4 and *5 alleles occurred at 7.3% and 1.9% respectively. The *3, *14 and *17 alleles were not detected in the study. The *1/*2, *1/*1 and *2/*2 genotypes were the most common CYP2D6 genotypes, representing 32.7%, 19.4% and 11.8% of the South Indian population. Genotypes that predict poor metabolizer phenotype i.e. *4/*4 and *4/*5 were found at 0.6% in South Indian population. The genetic composition at the CYP2D6 locus in South Indians is distinct from Caucasian, African and even other Asian (Chinese and Japanese) populations.     

Effects of CYP2C9 polymorphisms on the pharmacokinetics of R- and S-phenprocoumon in healthy volunteers

CYP2C9 catalyses the biotransformation of the oral anticoagulants S-warfarin and R- and S-acenocoumarol. According to data obtained in vitro, phenprocoumon is also metabolized by CYP2C9 but the impact of the CYP2C9 polymorphism on phenprocoumon pharmacokinetics has not been studied. Twenty-six healthy heterozygous and homozygous carriers of the CYP2C9 alleles *1 (wild-type), *2 (Arg144Cys), and *3 (Ile359Leu) received a single oral dose of 12 mg of racemic phenprocoumon. Plasma and 12 h urine concentrations of both enantiomers and their monohydroxylated metabolites were measured by high-performance liquid chromatography with mass spectrometry detection. No significant effect of the CYP2C9 variants *2 and *3 on R-phenprocoumon pharmacokinetic parameters was detected, but S-phenprocoumon clearance tended to decrease with increasing number of CYP2C9*2 and *3 alleles. The ratios of S- to R-phenprocoumon plasma clearances were higher with a median of 0.95 in carriers of *1/*1 versus 0.65 in *3/*3 (P < 0.001 for trend). Plasma and urine concentrations of 4'-, 6- and 7-hydroxyphenprocoumon were significantly lower in homozygous carriers of the CYP2C9*2 and *3 variants compared to CYP2C9*1/*1. Carriers of CYP2C9*3/*3 had a median AUC of (R,S) 7-OH-phenprocoumon of only approximately 25% compared to the wild-type genotype. The AUC of (R,S) 6-OH-phenprocoumon was only approximately 50% in CYP2C9*3/*3 compared to the homozygous wild-type genotype. In conclusion, carriers of CYP2C9*2 and *3 alleles had a lower metabolic capacity regarding phenprocoumon hydroxylation than those with CYP2C9*1/*1. However, regarding phenprocoumon hydroxylation CYP2C9 genotypes had only marginal effects on S- and R-phenprocoumon total clearance in healthy volunteers.     

Allele and genotype frequency of CYP2C19 in a Tamilian population

AIMS: To investigate the frequencies of CYP2C19*1, CYP2C19*2 and CYP2C19*3 alleles and CYP2C19 genotypes in a Tamilian population. METHODS: The study was conducted in 112 unrelated healthy human volunteers. DNA was extracted from leucocytes and analyzed by the PCR-RFLP protocol. The PCR product was digested with restriction enzymes (SmaI and BamH1) and then separated electrophoretically using polyacrylamide gel. RESULTS: The frequencies of the CYP2C19*1, *2 and *3 alleles were 0.598 [95% confidence interval (CI) 0.507, 0.689], 0.379 (95% CI, 0.350,0.407) and 0.022 (95% CI -0.005, 0.049), respectively. The distribution of CYP2C19*1/*1,*1/*2, *1/*3, *2/*2 and *2/*3 genotypes were 0.295 (95% CI, 0.210, 0.379), 0.580 (95% CI, 0.488, 0.671), 0.027 (95% CI -0.003, 0.057), 0.080 (95% CI 0.030, 0.130) and 0.018 (95% CI -0.006, 0.042), respectively. CONCLUSIONS: The distribution of CYP2C19*1/*1 in the Tamilian population is lower than that in Caucasians, Africans and the North Indian population. The CYP2C19*1/*2 is significantly higher in Tamilians when compared with other populations. The CYP2C19*1/*3 allele, which was not reported in the North Indian and Caucasian populations has been identified in 2.7% of the Tamilian population.