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.     

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.     

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.     

海南省黎族与汉族持续性心房颤动患者CYP2C9^*3基因多态性差异

目的:分析罹患持续性心房颤动的海南省黎族与汉族患者细胞色素P450酶2C9^*3(CYP2C9^*3)基因多态性分布,评估CYP2C9^*3基因多态性对患者稳定服用华法林剂量的影响。方法:选取2017年1月至2018年12月于海南医学院第二附属医院就诊的罹患持续性心房颤动的海南省黎族患者100例为研究组,同期海南医学院第二附属医院持续性心房颤动的汉族患者100例为对照组。记录两组研究对象的血清华法林浓度、国际标准化比率(international normalized ratio,INR)达标时间、华法林平均日剂量及总剂量;提取两组基因组DNA,采用扩增阻滞突变体系-聚合酶链式反应技术(amplification refractory mutation system,ARMS-PCR)对CYP2C9^*3基因位点进行基因分型。结果:研究组患者A/A与A/C基因型及等位基因A频率显著低于对照组(P<0.05),C/C基因型及C频率显著高于对照组(P<0.05)。两组不同基因型患者华法林稳定剂量及血清华法林浓度存在差异,均为A/A型最大(P<0.05),而A/C型与C/C型无差异(P>0.05);研究组A/A基因型患者华法林稳定剂量及血清华法林浓度低于对照组(P<0.05),但两组A/C与C/C基因型患者华法林稳定剂量及血清华法林浓度均无差异(P>0.05)。A/A基因型黎族持续性心房颤动患者的INR达标时间、华法林平均日剂量及总剂量最高,C/C基因型最低,A/C基因型次之(P<0.05)。结论:CYP2C9基因多态性与持续性心房颤动的海南省黎族患者稳定服用华法林剂量密切相关,C/C型CYP2C9基因持续性心房颤动的海南省黎族患者INR达标时间、华法林平均日剂量及总剂量更低。     

Malaysian Indians are genetically similar to Caucasians: CYP2C9 polymorphism

BACKGROUND: CYP2C9 is one of the major drug metabolizing enzymes for many drugs including warfarin, NSAIDs and losartan. It is polymorphic in many populations. Data on the distribution of CYP2C9 and the implication of CYP2C9 polymorphism in the Malaysian population is lacking. Our objectives were therefore to investigate the prevalence of CYP2C9 variants among unrelated healthy volunteers of Malays, Chinese and Indians in Malaysia. METHOD: Deoxyribonucleic acid was extracted using standard lysis methods. Allele specific polymerase chain reaction was performed for determination of CYP2C9*1, *2, *3, *4 and *5 variants according to Z. Zainuddin, L.K. Teh, A.W.M. Suhaimi, M.Z. Salleh, R. Ismail (2003, Clinica Chimica Acta, 336, 97). RESULT: The Chinese had the highest frequency of CYP2C9*1 (321/330, 97.27%), followed by the Malays and the Indians (402 of 420, 95.71% and 291 of 330, 88.18%, respectively). CYP2C9*2 was not found in the Chinese. CYP2C9*3 were detected in all the three races with the Indians having the highest frequency of CYP2C9*3 (9.7%). The Indians had a frequency of CYP2C9*2 and *3 similar to Tamilians and Caucasians. Two of the Indians had *2/*3 and one had *3/*3 genotypes and are likely to be slow metabolizers. No subject with CYP2C9*4 and *5 were detected in our populations. CONCLUSION: CYP2C9*2 and *3 were identified in our population. Indians are similar to Caucasians in terms of CYP2C9 genotypes and thus may respond to CYP2C9 substrates differently when compared with the Malays and Chinese in Malaysia.     

Frequency of CYP2C9 variant alleles, including CYP2C9*13 in a Korean population and effect on glimepiride pharmacokinetics

What is known and Objective: Cytochrome P450 (CYP) 2C9 is a clinically important enzyme involved in the metabolism of many drugs commonly used in humans. Of several allelic variants known to affect the catalytic activity of the CYP2C9 enzyme, the frequencies of the CYP2C9*3 and CYP2C9*13 alleles in the Korean population have been reported as 1·1% and 0·6%, respectively. Our objective was to re‐evaluate the frequencies of CYP2C9 allelic variants in the Korean population, including the CYP2C9*13 allele by pyrosequencing, and to investigate the pharmacokinetics of glimepiride in relation to CYP2C9 genotypes, including CYP2C9*3/*3. Methods: 295 subjects were genotyped for CYP2C9*2 and CYP2C9*3 using the TaqMan procedure, and for CYP2C9*13 using pyrosequencing. These data were combined with our previously reported data to assess the CYP2C9 allele and genotype frequencies in 869 Korean subjects. Data from 24 of the 295 genotyped subjects (22 CYP2C9*1/*1 homozygotes, one CYP2C9*1/*3 heterozygote and one CYP2C9*3/*3 homozygote) who had participated in a bioequivalence study were analysed retrospectively to examine the effects of CYP2C9 genotype on glimepiride pharmacokinetics. Results: The frequencies of the CYP2C9*1/*3, *3/*3, and *1/*13 genotypes in the study population (n = 295) were 0·081 (n = 24), 0·010 (n = 3) and 0·003 (n = 1), respectively. In the 869 subjects from the combined studies, allele frequencies for CYP2C9*3 and CYP2C9*13 were 0·025 (95% CI: 0·018, 0·033) and 0·002 (95% CI: 0·000, 0·010), respectively. Relative to CYP2C9*1 homozygotes, the one CYP2C9*3 homozygous subject was found to have a higher AUC_0–∞ value (490% of the reference value) and a lower oral clearance rate (18% of the reference). What is new and Conclusion: This study is the first examination of CYP2C9*3 homozygotes in the Korean population. Our data on the one subject with this genotype suggest that CYP2C9*3/*3 momozygotes have lower clearance of glimepiride and are exposed to higher levels of the drug than wild‐type homozygotes. Although we identified a subject with the CYP2C9*13 allele using a new pyrosequencing assay, we were unfortunately unable to investigate its effects on glimepiride pharmacokinetics.     

Genetic polymorphism of CYP2C8 in three Malaysian ethnics: CYP2C8*2 and CYP2C8*3 are found in Malaysian Indians

BACKGROUND: CYP2C8 is genetically polymorphic. Four variants, CYP2C8*2, CYP2C8*3, CYP2C8*4 and CYP2C8*5, which contain mutations in the coding regions have been reported to exhibit different enzyme activity as compared with CYP2C8*1. OBJECTIVE: To determine the allele frequency of three codon-changing variants (CYP2C8*2, CYP2C8*3 and CYP2C8*4) in the Malaysian population. METHOD: Healthy unrelated volunteers from three major races in Malaysia were recruited. The study was approved by the local Research Ethics Committee. DNA was extracted using a standard protocol. A two-step multiplex PCR method was developed to detect three alleles of CYP2C8. PCR results were confirmed by subsequent direct DNA sequencing. RESULT: Only the Indians showed CYP2C8 polymorphism with allele frequency of 98% for CYP2C8*1, 0.8% for CYP2C8*2 and 1.2% for CYP2C8*3. CYP2C8*4 was not detected in any of the ethnic groups. CONCLUSION: To the best of our knowledge, the current study described, for the first time polymorphisms of CYP2C8 in Malaysian Indians.     

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。     

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。     

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.     

CYP2C9和VKORC1基因多态性检测试剂盒的性能验证

目的 对华法林代谢相关的人细胞色素P450超家族第二亚家族C9代谢酶(CYP2C9)和维生素K环氧化物还原酶复合体亚单位1(VKORC1)基因多态性检测试剂盒进行性能验证.方法 根据中国合格评定国家认可委员会(CNAS)制定的有关要求,结合试剂说明书,从符合率、精密度、检出限、抗干扰能力4个方面对苏州旷远生物分子技术有...     

Clinical relevance of genetic polymorphisms in the human CYP2C9 gene

Cytochrome p450 (CYP) 2C9 hydroxylates about 16% of drugs in current clinical use. Of special interest are those with a narrow therapeutic index, such as S-warfarin, tolbutamide and phenytoin, where impairment in CYP2C9 metabolic activity might cause difficulties in dose adjustment as well as toxicity. Single-nucleotide polymorphisms (SNP) in the CYP2C9 gene have increasingly been recognized as determinants of the metabolic phenotype that underlies interindividual and ethnic differences. Apart from the wild-type protein CYP2C9*1 at least five allelic variants produce allozymes with reduced or deficient metabolic activity. Among white populations only CYP2C9*2 and CYP2C9*3 variants are of significance, with allelic frequencies of 0.08-0.14 and 0.04-0.16, respectively. In contrast, in Africans (African-Americans and Ethiopians) and Asians both variants are much less frequent (0.005-0.04), and CYP2C9*2 has not yet been detected in Asians. CYP2C9*4 has been exclusively identified in Japanese patients, and CYP2C9*5 and *6 were only found among African-Americans with a low allelic frequency of 0.017 and 0.006, respectively. Furthermore in Japanese a CYP2C9 promotor variant of four linked SNPs was correlated with reduced intrinsic clearance of phenytoin in vitro. Subjects who are carriers of one or more variant alleles may be at risk for adverse drug reactions/toxicities when prescribed drugs extensively metabolized by CYP2C9.     

中国健康人群与精神分裂症患者CYP2C9遗传多态性的相关研究

目的 探讨中国健康人群与精神分裂症患者细胞色素P450 2C9(CYP2C9)遗传多态性的相关性.方法 应用PCR与DNA测序相结合的方法对91例精神分裂症患者(男52例,女39例,平均年龄50.87±9.38岁)与164例健康志愿者(男88例,女76例,平均年龄47.37±14.82岁)进行了CYP2C9的基因多态性分析,根据CYP2C9将精神分裂症患者和健康志愿者基因型分组.结果 在对CYP2C9的检测中,没有发现CYP2C9*2基因型个体,正常对照组CYP2C9*3(A1075C)的等位基因频率为4%,精神分裂症患者组CYP2C9*3(A1075C)等位基因频率为5.5%,精神分裂症患者和健康志愿者组间的基因型和等位基因频率差异无统计学意义(χ2＝0.669,P>0.05;χ2=0.637,P>0.05).结论 CYP2C9 *3(A1075C)可能不是中国精神分裂症患者的一个易感因素.     

荧光PCR检测CYP2C19基因分型与氯吡格雷临床疗效的相关性研究

目的通过分析CYP2C19基因型与ADP抑制率之间的关系,探讨CYP2C19基因分型与氯吡格雷抗凝治疗效果的关系。方法选取急性冠脉综合征（ACS）并成功接受经皮冠状动脉介入治疗术（PCI）的患者55例,收集患者EDTA抗凝静脉血提取血液基因组DNA,用实时荧光PCR方法分析CYP2C19基因型,测定每名患者ADP抑制率,用统计学方法分析CYP2C19不同基因型患者ADP抑制率的差异。结果所有入组患者根据基因型不同分为快代谢组占49.09%（27/55）,中等代谢组占38.19%（21/55）,慢代谢组占12.73%（7/55）。三组ADP抑制率比较,两两相比差异均有统计学意义（P〈0.01）。结论 CYP2C19基因多态性与氯吡格雷抵抗存在关联,快代谢型患者PCI术后服用氯吡格雷疗效好于携带基因突变的患者,慢代谢型患者PCI术后服用氯吡格雷疗效差。     

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.     

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。     

Effect of antituberculosis treatment on CYP2C19 enzyme activity in genetically polymorphic South Indian Tamilian population

Patients on antituberculosis therapy (ATT) are more prone to drug interactions in the presence of coexisting illnesses which require drug therapy. Rifampicin is a pleiotropic inducer of CYP enzymes, and isoniazid is an enzyme inhibitor. Genetic variations are common in the gene coding for CYP2C19 enzyme. These variations would be important in predicting the individual variations in CYP2C19 activity. The objectives of the study were to find the net effect of 1‐month ATT on CYP2C19 enzyme activity and its association with CYP2C19 genetic polymorphisms. Newly diagnosed tuberculosis patients (n = 125) were included in the study. Before commencing ATT, they were given a single dose of omeprazole 20 mg as a probe drug for CYP2C19. Blood sample was collected after 3 h to carry out phenotyping for CYP2C19 enzyme by measuring omeprazole hydroxylation index (OHI) using LC‐MS/MS. The phenotyping procedure was repeated after 1 month of ATT. CYP2C19 genotyping was carried out by PCR‐RFLP method. Significant reduction in OHI was observed after 1 month of ATT in all the metabolizer groups. The percentage reduction in OHI was maximum with poor metabolizers, 84.1 (IQR – 74.6, 86.6), and minimum with ultra‐rapid metabolizers, 39.6 (IQR – 12.7, 54.7). CYP2C19 enzyme induction is predominant in patients after 1 month of antituberculosis treatment (ATT). Genetic variations in the enzyme could not clearly explain the interindividual differences in induction. There is a potential risk of drug failure/adverse effect in poor metabolizers regardless of their genotype after ATT.