细胞色素P-450 CYP2D6基因分型与表型的吻合率

目的:研究细胞色素P-450 2D6基因分型测定方法及其与表型的吻合率。方法:利用等位基因特异扩增法基本原理,对CYP2D6酶缺陷等位基因CYP2D6*3,*4,*6和*7进行测定。结果:通过168例基因分型,并将结果与表型对照,发现同时测定CYP2D6*3,*4,*6和*7等位基因时,125例快代谢者和43例慢代谢者的基因分型结果与表型结果的吻合率为100％。快代谢者至少有一个野生型CYP2D6等位基因,基因型为*1/*1,*1/*3和*1/*4。发现慢代谢者是CYP2D6突变型纯合子,基因型为*3/*4,*4/*4,*3/*6,*4/*7,*4/*6和*6/*6。结论:对CYP2D6*3,*4,*6和*7等位基因的测定能够准确预测其表型。     

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)。     

CYP2D6基因多态性对帕罗西汀在中国健康人药动学影响

目的研究中国健康人CYP2D6基因多态性对帕罗西汀药动学的影响。方法使用PCR-RFLP方法将23位志愿者分为3组:CYP2D6*1/*1组(n=5),CYP2D6*1/*10组(n=7),CYP2D6*10/*10组(n=11)。给予帕罗西汀20 mg单剂量口服,收集给药后96 h内的一系列血样,用LC-MS/MS法测定帕罗西汀的血药浓度并做药动学分析。结果与CYP2D6*1/*1组药动学参数相比,CYP2D6*1/*10组t_(max)、t1/2和CYP2D6*10/*10组t_(max)无显著差异(P>0.05);CYP2D6*1/*10、CYP2D6*10/*10组的ρ_(max)、AUC_(0-96 h)、AUC_(0-∞)、CL(F)、Vd和CYP2D6*10/*10组t_(1/2)均有显著差异(P<0.05或P<0.01)。结论 CYP2D6*10等位基因突变能引起代谢表型的改变,影响帕罗西汀在健康人的体内代谢。     

细胞色素P4502D6酶基因多态性与利培酮代谢的相关性研究

目的 研究利培酮(抗精神分裂症药)在人体代谢过程与CYP2D6*10基因多态性的关系.方法 不同CYP2D6*1/*1(n=5)、*1/*10(n=12)及*10/*10(n=6)基因型的健康志愿者,单次口服利培酮2 mg后,用LC-MS/MS方法测定血浆中利培酮及其活性代谢产物9-羟基利培酮浓度,研究利培酮药代动力学与CYP2D6*10基因型的相关性.结果 CYP2D6*10/*10和CYP2D6*1/*10基因型与CYP2D6*1/*1基因型的受试者相比,利培酮的AUC0-∞分别增加811%和212%,2者比较差异非常显著(P<0.001);利培酮/9-羟基利培酮的AUC比值在各CYP2D6*10基因型间存在显著性差异(P<0.001).结论 CYP2D6*10 C188T突变使CYP2D6对利培酮的代谢活性降低,体内利培酮暴露量增加.     

CYP2C19基因多态性与肝癌易感性关系的研究

目的 研究内蒙古地区汉族人群CYP2C19基因多态性与肝癌易感性的关系.方法 采用等位基因特异性扩增(ASA)技术对内蒙古地区254例汉族健康人和68例汉族肝癌患者进行CYP2C19基因型分布频率的研究,分析CYP2C19基因多态性与肝癌易感性的关系.结果 CYP2C19ml 3种多态基因型在内蒙古地区汉族人群肝癌组与对照组的分布频率分别为:wt/wt 50％、wt/ml 33.8％、ml/ml 16.2％和wt/wt 40.6％、wt/ml 50.3％、ml/ml9.1％.结果 显示携带CYP2C19ml突变杂合型(wt/ml)的个体患肝癌的风险度比野生型纯合子(wt/wt)升高1.8倍,经统计学检验差异有显著性(P＜0.05).CYP2C19m2基因型在内蒙古地区汉族人群肝癌组与对照组的分布频率分别为wt/wt 85.3％、wt/m2 14.7％和wt/wt 91.3％、wt/m2 8.7％,两者之间比较差异无统计学意义(P＞0.05).对照组中CYP2C19快代谢者占87％,慢代谢者占13％;肝癌组中快代谢者占72.1％,慢代谢者占27.9％,经统计学检验差异有显著性(P＜0.05).慢代谢型患肝癌的危险是快代谢型的2.6倍.结论 携带突变杂合型CYP2C19ml基因型者肝癌的易感性增加,CYP2C19慢代谢型与肝癌的风险有关.     

宁夏回族人群CYP2D6*10基因多态性及功能分析

目的 探讨基因突变对人CYP2D6蛋白结构与功能的影响.方法 采用等位基因特异扩增(ASA-PCR)及DNA测序技术分析宁夏网族人群CYP2D6*10(C188T)基因多态性,以生物信息学方法对突变造成的肝药酶活性的下降做出合理的解释.结果 蛋白质基本性质分析工具(ProtParam)分析显示,在溶液中CYP2D6*10突变型蛋白的不稳定指数高于野生型,都高于阈值40;二级结构预测软件(DNAStar/Protean)分析显示,突变型蛋白的二级结构在第33位多了一个转角(Gamier-Robson Turn);功能佗点预测程序(Motif Scan)对蛋白功能位点进行预测,结果显示CYP2D6*10野生型蛋白有2个P450酶激活位点.而突变型没有;信号肽预测程序(Signal P)分析显示.神经网络模型(NN)C-score计算结果为突变型蛋白没有信号肽,而野牛型有.结论 基因突变可引起CYP2D6蛋白结构与功能的改变;应用生物信息学方法对CYP2D6基因突变致使的酶活性的下降做出一些可能的解释是可行的.     

CYP2B6*6基因多态性对依法韦仑在中国人群药动学的影响(英文)

目的研究中国健康人CYP2B6*6基因多态性对依法韦仑药动学的影响。方法应用聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)将40名健康中国志愿者分为3组:CYP2B6*1/*1组(n=29),CYP2B6*1/*6组(n=8)和CYP2B6*6/*6组(n=3)。受试者单剂量口服依法韦仑600 mg,收集给药后336 h内的一系列血样,用HPLC-MS/MS法测定依法韦仑的血药浓度并进行药动学分析。结果与CYP2B6*1/*1组相比,CYP2B6*6/*6基因型的志愿者的依法韦仑血药浓度较高(P<0.05);CYP2B6*1/*6组与CYP2B6*6/*6组的主要药动学参数(t1/2、AUC0-336 h和AUC0-∞)均存在显著差异(P<0.05或P<0.01);CYP2B6*1/*6组与CYP2B6*6/*6组的tmax和ρmax无显著差异(P>0.05)。结论 CYP2B6*6等位基因突变能引起代谢表型的改变,影响依法韦仑在中国健康人群的代谢。根据基因型制定个体化给药方案有助于依法韦仑的合理使用。     

ASA法测定细胞色素P450 2D6酶缺陷等位基因CYP2D6E

目的 :建立细胞色素P4 50 2D6(CYP2D6)第 3 0 2 3位A→C突变造成CYP2D6酶活性缺陷的等位基因CYP2D6E的测定方法。方法 :利用等位基因特异扩增法 (ASA)为基本原理 ,设计两对引物分别扩增野生型等位基因和突变型等位基因。结果 :经 3 96例测定 ,发现 2例CYP2D6E与CYP2D6B的异突变型纯合子 ,其表现型均为慢代谢者。阳性对照说明本法重复性好 ,阴性对照显示本法无污染问题。结论 :本法比PCR -RFLP法更为快捷、更少污染。对CYP2D6E的测定有助于准确预测CYP2D6表现型     

突变阻断扩增法检测中国人CYP2D6＊10、＊14等位基因

目的根据突变阻断扩增原理,建立用于检测中国人CYP2D6＊10及＊14等位基因的方法。方法采用单管四引物法检测CYP2D6＊10等位基因,建立等位基因特异扩增法检测CYP2D6＊14等位基因,检测295名健康中国汉族人CYP2D6＊10等位基因。结果CYP2D6＊10及＊14等位基因基因频率分别为55．8％和1．8％,295位受试者中包括1位＊14／＊14、6位＊1／＊14、3位＊10／＊14,基因型分布符合Hardy—Weinberg平衡（Χ^2=2．15,df=5,P〉0．82）。结论本室建立的CYP2D6＊10、＊14等位基因分析法具有方便快捷、结果准确可靠的特点。     

2467例中国汉族患者CYP2D6基因多态性分布频率研究

目的 回顾性分析CYP2D6基因多态性在中国汉族人群中的分布情况,探讨CYP2D6基因检测对其敏感底物药物美托洛尔、他莫昔芬、可待因代谢的意义。方法 对2018年12月至2020年1月在首都医科大学附属北京安贞医院完成CYP2D6基因型检测的门诊和住院患者进行汇总分析。结果 共有2479例服用美托洛尔的患者进行了CYP2D6基因型检测,其中少数民族患者12例,汉族患者2467例。汉族人群最常见等位基因型是野生型^*1、活性无改变的突变型^*2和酶功能降低的突变^*10;主要的双倍型是^*1/^*10(37.9%)、^*10/^*10(27.7%)和^*1/^*1(25.0%)。检测结果显示,无超快代谢型和慢代谢型患者,正常代谢型患者占比高达72.1%,而CYP2D6^*10/^*10基因型的中间代谢型患者占比高达27.7%。结论 中国汉族人群CYP2D6基因型分布有自身...     

CYPD6＊10基因型对中国室性心律失常病人普罗帕酮药效学的影响

AIM: To determine the effect of CYP2D6*10 genotype on propafenone pharmacodynamics in Chinese patients with ventricular arrhythmia. METHODS: Seventeen Chinese patients with ventricular premature contractions (VPC> or =1000/d) were recruited. They were normal in routine laboratory testing and administered propafenone hydrochloride 450-600 mg per day in three divided doses. Twelve lead cardiogram and 24 h Holter monitoring were performed before and after 7 d treatment of propafenone. Steady-state peak and trough concentrations of propafenone were measured by HPLC method. CYP2D6*10 genotypes of patients were assayed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). RESULTS: Total inhibitory rate of VPC was 79.9 % in 17 patients with ventricular arrhythmia after propafenone treatment. PR interval prolongation was increased from 0.146 s+/-0.018 s to 0.161 s+/-0.022 s (P<0.05). CYP2D6 genotypes played an important role in plasma levels and effects of propafenone. In 450 mg/d group, patients with homozygous mutant of CYP2D6*10 not only had a Cmax of propafenone two times as high as those of wild-type genotype, but also showed a two fold higher inhibitory rate of VPC compared with those with homozygous CYP2D6*1 (P<0.05). CONCLUSION: CYP2D6*10 genotype is relevant to decreased activity of CYP2D6 enzyme in Chinese patients. Elevated plasma concentration is consistent with better efficacy of propafenone in patients with ventricular arrhythmia.     

Sequence-based CYP2D6 genotyping in the Korean population

For clinical application of pharmacogenetic tests, quantitative prediction of enzyme activity based on accurate determination of genotype is essential. There has been limited information available on the genetic polymorphism of CYP2D6 in the Korean population. In this study, CYP2D6 genotypes were assessed in 400 Korean subjects. Twenty-eight different CYP2D6 alleles and 35 genotypes were detected. On the basis of the genotype determined, the frequency of poor metabolizers and ultrarapid metabolizers were 0.22% and 1.25%, respectively. The CYP2D6 activity expected in regard to different allele combinations varies widely within the extensive and intermediate metabolizer groups. The frequencies of CYP2D6*10 and CYP2D6*5 were 45.00% and 6.13%, respectively. CYP2D6*10xN was found in 4 out of 9 cases with a CYP2D6 duplication. Fifteen heterozygotes for *41 were noted. In addition, the authors measured plasma concentrations of 16 healthy volunteers after administration of nortriptyline and identified the impact of the CYP2D6 genotype on nortriptyline metabolism. This is the first large-scale study to examine the genetic polymorphism of CYP2D6 using sequence-based genotyping in an Asian population. Our results further the understanding of CYP2D6 pharmacogenetics and could be helpful for future clinical studies in the Asian population.     

CYP2D6 extensive,intermediate, and poor phenotypes and genotypes in a Polish population

OBJECTIVE: This study investigated the distribution of the CYP2D6 genotypes and phenotypes in a Polish population and compared the concordance of the two methods. METHODS: Six hundred unrelated healthy individuals from southwestern Poland were studied. The CYP2D6 phenotype was analyzed in 300 individuals using sparteine as a model drug. The CYP2D6 genotype was analyzed in 300 individuals by polymerase chain reaction amplification and restriction fragment length polymorphism techniques for the CYP2D6*1, CYP2D6*3, and CYP2D6*4 alleles. Additionally, in 60 randomly selected healthy individuals both the CYP2D6 phenotype and genotype was assessed to determine accordance between the methods. RESULTS: Of 300 participants in the study 25 (8.3%) were classified as poor metabolizers, 44 (14.7%) as intermediate metabolizers, and 231 (77%) as extensive metabolizers of sparteine. The frequency of CYP2D6*1, CYP2D6*3, and CYP2D6*4 alleles among the genotyped 300 persons was 75.7%, 1.3%, and 23.0%, respectively. The frequency of CYP2D6 deficient genotypes in a Polish population (8.0%) was similar to phenotyping results. The comparison of phenotype and genotype in 60 randomly selected individuals showed a good concordance of the obtained results. CONCLUSIONS. The frequencies of poor metabolizers for CYP2D6 phenotype (8.3%) and genotype (8.0%) in a Polish population from the southwestern region are in concordance and compare well with most results of poor oxidation metabolizers in other white populations.     

Effect of the CYP2D6 genotype on metoprolol metabolism persists during long-term treatment

The beta1 selective beta-blocker metoprolol is metabolized predominantly but not exclusively by CYP2D6. Due to the polymorphism of the CYP2D6 gene, CYP2D6 activity varies markedly between individuals. Consequently, after short-term administration metoprolol plasma concentrations were found to be several fold higher in poor metabolizers than in extensive metabolizers. However, it is currently not known, whether the impact of the CYP2D6 polymorphism persists during long-term therapy, since alternate mechanisms of elimination or metabolism could be effective in this setting. The study comprised 91 Caucasian patients on long-term treatment with metoprolol (median duration of treatment 12.6 months; median daily drug dose: 47.5 mg/day). Metoprolol and alpha-OH-metoprolol plasma concentrations were assessed by HPLC. Genotyping detected the null alleles (*0): *3, *4, *5, *6, *7, *8, *12, *14, *15, the alleles *9, *10 and *41 associated with reduced enzymatic activity as well as the fully functional alleles *1 and *2. Genotype and allele frequencies were in accordance with published frequencies for the German population. The plasma metabolic ratio of metoprolol/alpha-OH-metoprolol was markedly affected by the genotype (P < 0.0001). In accordance, median adjusted metoprolol plasma concentrations were 6.2- and 3.9-fold higher in patients with *0/*0 genotypes (n = 8) and intermediate genotypes (n = 10), respectively, as compared to those with two fully functional alleles (n = 31; P < 0.01). In summary, the pronounced effect of the CYP2D6 genotype persists during long-term therapy, affecting both metabolic ratio and metoprolol plasma concentration.     

CYP2D6^＊10B基因型对中国人普罗帕酮对映体药动学的影响

AIM: To study the relationship between genotype of CYP2D6*10B and pharmacokinetics of propafenone enantiomers. METHODS: Genotype of 17 healthy Chinese HAN subjects was determined by an allele specific amplification method. The blood samples (0-15 h) of the subjects were taken after oral administration of a single dose (400 mg) of propafenone hydrochloride. Concentrations of propafenone enantiomers in plasma were measured by a reverse-phase HPLC with precolumn derivatization. RESULTS: Seventeen subjects characterized for CYP2D6*10B genotype included (*1/*1) (n=4), (*1/*10) (n=5) and (*10/*10) (n=8). The metabolic ratios (lg MR) of the three genotypes were -2.68+/-0.23, -2.2+/-0.7, and -1.1+/-0.5, respectively. The AUC of the three groups were (1534+/-334), (1891+/-793), (3171+/-1075) microg.h.L(-1) for S-enantiomer and (1136+/-345), (1467+/-817), (2277+/-745) microg.h.L(-1) for R-enantiomer, respectively. The AUC of propafenone enantiomers in *10/*10 is about 1.5-2 times of that of *1/*10 group or *1/*1 group, and the CL of both enantiomers in *10/*10 is only half of that of *1/*10 group or *1/*1 group (P<0.05). CONCLUSION: CYP2D6*10B alleles induce the declined activity of CYP2D6 and impair the metabolism of propafenone.     

Combined effects of itraconazole and CYP2D6*10 genetic polymorphism on the pharmacokinetics and pharmacodynamics of haloperidol in healthy subjects

This study was to evaluate the combined effects of the CYP3A4 inhibitor itraconazole and the CYP2D6*10 genotype on the pharmacokinetics and pharmacodynamics of haloperidol, a substrate of both CYP2D6 and CYP3A4, in healthy subjects. Nineteen healthy volunteers whose CYP2D6 genotypes were predetermined were enrolled (9 for CYP2D6*1/*1 and 10 for CYP2D6*10/*10). Four subjects (1 for CYP2D6*1/*1 and 3 for CYP2D6*10/*10) did not complete the study because of adverse events. The pharmacokinetics of haloperidol and its pharmacodynamic effects measured for QTc prolongation and neurologic side effects were evaluated after a single dose of 5 mg haloperidol following a pretreatment of placebo or itraconazole at 200 mg/d for 10 days in a randomized crossover manner. Itraconazole pretreatment increased the mean area under the time-concentration curves (AUCs) of haloperidol by 55% compared to placebo pretreatment (21.7 +/- 11.3 vs 33.5 +/- 29.3 ng h/mL). The subjects with CYP2D6*10/*10 genotype showed 81% higher AUC compared to that of subjects with CYP2D6*1/*1 genotype (27.6 +/- 22.2 vs 50.2 +/- 47.1 ng h/mL). In the presence of itraconazole, subjects with CYP2D6*10/*10 showed 3-fold higher AUC of haloperidol compared to that of placebo pretreated subjects with CYP2D6*1/*1 genotype (21.7 +/- 11.3 vs 66.7 +/- 62.1 ng h/mL; P < 0.05). The CYP2D6*10 genotype and itraconazole pretreatment decreased the oral clearance of haloperidol by 24% and 25%, respectively, but without a statistical significance. In the subjects with both CYP2D6*10 genotype and itraconazole pretreatment, however, the oral clearance was significantly decreased to 42% of subjects with wild genotype in the placebo pretreatment (4.7 +/- 3.6 vs 2.0 +/- 1.9 L/h/kg; P < 0.05). Barnes Akathisia Rating Scale (BARS) of subjects with CYP2D6*10/*10 in the presence of itraconazole pretreatment was significantly higher than that of subjects with CYP2D6*1/*1 genotype in the period of placebo pretreatment. Except for this, all other pharmacodynamic estimations did not reach to statistical significance although each CYP2D6*10 genotype and itraconazole pretreatment caused higher value of UKU side effect and BARS scores. The moderate effect of CYP2D6*10 genotype on the pharmacokinetics and pharmacodynamics of haloperidol seems to be augmented by the presence of itraconazole pretreatment.     

中国汉族和蒙族人群细胞色素氧化酶CYP2C19 遗传多态性的比较

目的：比较中国汉族与蒙族健康人群细胞色素氧化酶CYP2C19遗传多态性。方法：应用限制性片段长度多态性分析法(PCR-RFLP)，对74名汉族健康志愿和6名蒙族健康志愿进行基因多态性分析。结果：蒙族中基因型为野生型纯合子wt／wt的发生率为16．7％(1／6)，汉族中发生率为41．9％(31／74)；蒙族基因型为杂合子wt/ml和wt／m2的为50％(3／6)，汉族中为45．9％(34／74)；蒙族基因型为突变型纯合子m1／m1和m1／m2的为33．3％(2／6)，汉族中为12．2％(9／74)。本实验未发现m2／m2基因型。结论：在中国蒙族和汉族受试中，wt／wt和m1／m1的发生率没有显差别。中国蒙族和汉族健康人群细胞色素氧化酶CYP2C19遗传多态性未显示出统计学差别。     

中国汉族人群S-美芬妥英4'-羟化酶的表型与基因分析

目的：研究中国汉族人群S-美芬妥英4'-羟化代谢遗传多态性。方法：以美芬妥英为探针药物采用手性毛细管气相色谱法测定尿中S-/R-MP浓度比值, 对90名志愿者进行了表型分型测定,应用PCR技术对其中的26名志愿者进行了S-美芬妥英4'-羟化酶（CYP2C19）基因分析。结果：表型分析结果,11人属慢代谢者（PM）,S/R比值0.95;基因分析结果,6人为野生型纯合子（wt/wt）;10人为杂合子（wt/m₁和wt/m₂）,9人为CYP2C19m₁突变型纯合子（m₁/m₁）,1人为两突变型杂合子（m₁/m₂）。结论：表型分析与基因分析结果显示了很好的相关性,本实验测得慢代谢者的频发率为12.2%,与文献报道相符。     

Nicotine metabolism and CYP2A6 allele frequencies in Koreans.

CYP2A6 is a major catalyst of nicotine metabolism to cotinine. Previously, we demonstrated that the interindividual difference in nicotine metabolism is related to a genetic polymorphism of the CYP2A6 gene in Japanese. To clarify the ethnic differences in nicotine metabolism and frequencies of CYP2A6 alleles, we studied nicotine metabolism and the CYP2A6 genotype in 209 Koreans. The cotinine/nicotine ratio of the plasma concentration 2 h after chewing one piece of nicotine gum was calculated as an index of nicotine metabolism. The genotypes of CYP2A6 gene (CYP2A6*1A, CYP2A6*1B, CYP2A6*2, CYP2A6*3, CYP2A6*4 and CYP2A6*5) were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism or allele specific (AS)-PCR. There were ethnic differences in the allele frequencies of CYP2A6*1A, CYP2A6*1B, CYP2A6*4 and CYP2A6*5 between Koreans (45.7%, 42.8%, 11.0% and 0.5%, respectively) and Japanese (42.4%, 37.5%, 20.1% and 0%, respectively, our previous data). Similar to the Japanese, no CYP2A6*2 and CYP2A6*3 alleles were found in Koreans. The homozygotes of the CYP2A6*4 allele (four subjects) were completely deficient in cotinine formation, being consistent with the data among Japanese. The heterozygotes of CYP2A6*4 tended to possess a lower metabolic ratio (CYP2A6*1A/CYP2A6*4, 4.79 +/- 3.17; CYP2A6*1B/CYP2A6*4, 7.43 +/- 4.97) than that in subjects without the allele (CYP2A6*1A/CYP2A6*1A, 7.42 +/- 6.56; CYP2A6*1A/CYP2A6*1B, 9.85 +/- 16.12; CYP2A6*1B/CYP2A6*1B, 11.33 +/- 9.33). The subjects who possess the CYP2A6*1B allele appeared to show higher capabilities of cotinine formation. It was confirmed that the interindividual difference in nicotine metabolism was closely related to the genetic polymorphism of CYP2A6. The probit plot of the metabolic ratios in Koreans (8.73 +/- 11.88) was shifted to a higher ratio than that in the Japanese (3.78 +/- 3.09). In each genotype group, the Korean subjects revealed significantly higher metabolic ratios than the Japanese subjects. The ethnic difference in cotinine formation might be due to environmental and/or diet factors as well as genetic factors.