A systematic genetic polymorphism analysis of the CYP2C9 gene in four different geographical Han populations in mainland China

While many studies have been focused on CYP2C9*2 and *3 there was a lack of large full gene sequencing on CYP2C9, and this study was designed to fill this gap. We used direct sequencing to systematically screen genetic polymorphisms of the CYP2C9 gene including the 5' -flanking region (2kb), all exons and their adjoining intron regions and the 3' UTR in 400 unrelated healthy Chinese Han volunteers. A total of 27 different CYP2C9 polymorphisms were identified, 3 of which were novel, including one in intron 6, a synonymous variant (1137T>C, Tyr379Tyr), and a deletion mutation in the 3'UTR (1739-1740ATdel), which potentially influences the stability of CYP2C9 mRNA. We identified CYP2C9*1, *2, *3, *8, *11, and *31, of which alleles *8 was identified for the first time in Chinese population while *11 first in Asian. This is the first systematic screening of genetic polymorphisms of CYP2C9 in the Chinese Han population.     

Systematic polymorphism analysis of the CYP2D6 gene in four different geographical Han populations in mainland China

In this study, we systematically screened the polymorphisms of the whole CYP2D6 gene in the populations of four different geographical locations in China, namely, Shanghai, Shantou, Shenyang, and Xi'an, using a sample of 100 subjects from each population. Forty-eight different polymorphisms were detected as well as 12 novel ones. One novel nonsynonymous SNP was detected, and one novel intronic SNP was revealed that might inactivate a cryptic donor site 392 nucleotides downstream of the exon 6 natural donor site. In addition, the frequencies of some polymorphisms and alleles demonstrated significant differences among the four populations. Linkage disequilibrium analysis and tag SNP selection were performed separately for each population. Haplotypes were analyzed within the selected tag SNPs. Tag SNP selection and haplotype distributions showed differences across the four populations. This is the first large-scale study to analyze polymorphisms systematically across the whole CYP2D6 gene in the Chinese Han population.     

Skin reflectance in the Han Chinese and Tibetan populations.

Genetic and environmental factors are involved in the determination of skin pigmentation in humans. With the recent development of statistical and genetic tools in mapping complex traits in humans, it is becoming feasible to utilize such methods in identifying genes involved in skin pigmentation. Furthermore, the use of new portable reflectance spectroscopy instruments such as the Photovolt ColorWalk colorimeter allows researchers to measure skin reflectance of a large number of subjects with ease and accuracy. We used a new portable instrument (Photovolt ColorWalk) to study the skin reflectance of 372 Han Chinese and 274 Tibetan individuals to establish background reflectance measurements of unexposed skin of the inner upper arm in these two populations. In addition, we explored the effect of various factors such as age and gender on skin reflectance.     

Genetic polymorphisms of CYP2C8, CYP2C9 and CYP2C19 in Ecuadorian Mestizo and Spaniard populations: a comparative study

This study was designed to investigate the potential differences between Spaniards and Ecuadorian Mestizo people regarding CYP2C8, CYP2C9, and CYP2C19 genetic polymorphisms. DNA from 282 Spaniard and 297 Ecuadorian subjects were analyzed by either a previously reported pyrosequencing method (CY2C8*3, CYP2C9*2, CYP2C9*3, CYP2C19*2 and CYP2C19*3) or a nested PCR technique (CYP2C19*17). Whereas CYP2C19*17 allele distribution was higher in Ecuadorians than in Spaniards (P < 0.001) and the frequency of CYP2C19*3 was similar in these two populations (P > 0.05), the other allelic variants were detected at significantly lower frequencies in Ecuadorians than in Spaniards (P < 0.05). According to the diplotype distributions, the prevalence of the presumed CYP2C9 and CYP2C8 extensive metabolizers was higher in Ecuadorians than in Spaniards (P < 0.05). Individuals genotyped CYP2C19*1/*17 and *17/*17 who were considered as ultrarapid metabolizers were overrepresented in Ecuadorians in relation to Spaniards (P < 0.001). By contrast, among Ecuadorians no poor metabolizers (PMs) of either CYP2C8 or CYP2C9 were found and only two individuals were CYP2C19 PMs. These data are compatible with a higher CYP2C8, CYP2C9, and CYP2C19 activity in Mestizo Ecuadorians as opposed to Spaniards, which could imply differences in dosage requirements for drugs metabolized by these cytochromes and should also be considered in allele-disease association studies.     

Association of CYP2C9 gene polymorphism with bleeding as a complication of warfarin therapy

The aim of this study was to determine the association of bleeding as a complication of warfarin therapy with polymorphism of CYP2C9 gene (alleles 1, 2 and 3). The CYP2C9 is the main enzyme for warfarin metabolism. Study included 181 patients receiving warfarin for at least one month. Allele 1 of CYP2C9 gene (in 94.5%) and genotype *1/*1 (57.5%) prevailed. Allele 3 was found in 12.7% patients. Bleeding side-effects occurred in 18 patients (10%). Patients with allele *1 needed significantly higher maintenance warfarin dose (p=0.011). Those with allele *3 had significantly lower maintenance warfarin dose (p=0.005) and higher prothrombin time (PT) at induction (p=0.034). Bleeding occurred significantly more often in those with lower maintenance warfarin dose (p=0.017). Patients with allele *3 had increased risk of bleeding, with marginal significance (p=0.05). Polymorphism of CYP2C9 could determine dose of warfarin therapy and thus it could be related to the risk of bleeding complications. Allele *3 carriers need lower warfarin dose. Therefore, initially reduced warfarin induction dose in allele *3 carriers could avoid more prolonged PT and decrease the risk of bleeding complication.     

Association of CYP2C19*3 gene polymorphism with breast cancer in Chinese women

Cytochrome P450 (CYP) 2C19 metabolizes arachidonic acid to biologically active epoxyeicosatrienoic acids, which significantly promote proliferation of cancer cells in vitro and in vivo. We looked for a possible association between human CYP2C19*3 gene polymorphism and breast cancer in the Chinese Han population. In a Chinese Han case-control study of breast cancer patients (N = 600) and age- and gender-matched healthy controls (N = 600), we investigated polymorphism in the CYP2C19 gene by PCR-RFLP analysis. The CYP2C19*3 AG + AA genotype was significantly more prevalent in breast cancer patients than in control subjects (6.67 vs 3.00%; P = 0.003). The odds ratio for carriers of AG + AA genotype for breast cancer was 2.31 (95% confidence interval = 1.27-4.43). Among patients, estrogen receptor, tumor size, histologic grade, presence of primary lymphonode metastases, progesterone receptor positivity, and age at diagnosis were not found to be significantly associated with CYP2C19*3 genotypes (all P > 0.05). We conclude that the CYP2C19*3 gene polymorphism is associated with breast cancer risk in Chinese Han women.     

Interaction between CYP 2C19*3 polymorphism and smoking in relation to laryngeal carcinoma in the Chinese Han population

Cytochrome P450 (CYP) 2C19 metabolizes arachidonic acid to biologically active epoxyeicosatrienoic acids, which strongly promote proliferation of cancer cells in vitro and in vivo. Knowing that smoking is the most important risk factor for laryngeal carcinoma, we examined the relationships between CYP2C19*3 polymorphism, smoking and laryngeal carcinoma in the Chinese Han population. In a Chinese Han case-control study of 300 laryngeal carcinoma patients and 300 healthy controls, we investigated polymorphism in the CYP2C19 gene by PCR-RFLP analysis. The CYP2C19*3 AG + AA genotype was significantly more prevalent in laryngeal carcinoma patients (6.67 vs 2.67%; P = 0.02). Multiple logistic regression analysis showed smoking (odds ratio (OR) = 6.353, 95% confidence interval (CI) = 4.413-9.144; P < 0.001) and alcohol consumption (OR = 2.607, 95%CI = 1.130-6.016; P = 0.025) as independent risk factors for laryngeal carcinoma; there was a significant interaction between CYP2C19*3 and smoking (OR = 17.842, 95%CI = 13.32-31.102; P = 0.009). We conclude that CYP2C19*3 polymorphism is significantly associated with laryngeal carcinoma in the Chinese Han population.     

Study on the distribution of the MSY2 polymorphism in 9 Chinese populations

The distribution of the MSY2 polymorphism in Chinese populations was analyzed by PCR. The results showed that the MSY2*4 allele, whose frequency in the total material was found to be 94.95%, was the common allele, while the distribution of the MSY2*3 allele was significantly different in the 416 tested males from the 9 populations under study. Based on the chi2-analysis, a distinct diversity was found in the non-group populations. Diversities were also discovered between southern and northern groups and among southern groups. On the contrary, no difference concerning the diversity was detected among the northern populations. In conclusion, MSY2 proved to be an important genetic marker with regard to the study of the genetic structure of Chinese populations, and further evidence is given concerning the migration direction between South and North.     

Linkage between the CYP2C8 and CYP2C9 genetic polymorphisms

Cytochrome P450 (CYP) 2C8 and 2C9 are polymorphic enzymes. The CYP2C8*3 and CYP2C9*2 are the major variant alleles in Caucasian populations. The enzymes encoded by these variant alleles have impaired function for the metabolism of several drug substrates. In the present study 1468 subjects that were used as population-based controls in the Stockholm Heart Epidemiology Program (SHEEP) were genotyped by allelic discrimination using a 5'-nuclease assay for CYP2C8*1, 2C8*3, 2C9*1, 2C9*2, and 2C9*3 variant alleles in which the frequencies appeared to be 0.91, 0.095, 0.83, 0.11, and 0.066, respectively. Approximately, 96% of the subjects with CYP2C8*3 allele also carried a CYP2C9*2 and 85% of the subjects that had CYP2C9*2 variant also carried a CYP2C8*3. The number of subjects carrying both of the CYP2C8*1*3 and CYP2C9*1*2 was 4.5-fold higher than expected. This strong association may be of importance especially for the metabolism of common substrates of CYP2C8 and CYP2C9 like arachidonic acid that produces physiologically active metabolites.     

Lipophilicity Relationships in Inhibitors of CYP2C9 and CYP2C19 Enzymes

Quantitative structure-activity relationships (QSARs) within a series of cytochrome P450 2C9 (CYP2C9) and cytochrome P450 2C19 (CYP2C19) inhibitors are reported. In particular, it is noted that compound lipophilicity, in the form of log P values (where P is the octanol/water partition coefficient), is an important factor in explaining the variation in inhibitory potency within these series of compounds, many of which also act as substrates for the respective enzymes. In addition, there is a role for hydrogen bonding and π-π stacking interactions within the P450 active site which represent secondary factors in the binding processes of these compounds.     

Lipophilicity relationships in inhibitors of CYP2C9 and CYP2C19 enzymes

Quantitative structure-activity relationships (QSARs) within a series of cytochrome P450 2C9 (CYP2C9) and cytochrome P450 2C19 (CYP2C19) inhibitors are reported. In particular, it is noted that compound lipophilicity, in the form of log P values (where P is the octanol/water partition coefficient), is an important factor in explaining the variation in inhibitory potency within these series of compounds, many of which also act as substrates for the respective enzymes. In addition, there is a role for hydrogen bonding and pi-pi stacking interactions within the P450 active site which represent secondary factors in the binding processes of these compounds.     

Genetic polymorphism analysis of cytochrome P4502E1 (CYP2E1) in Chinese Han populations from four different geographic areas of Mainland China

CYP2E1 is one of a superfamily of enzymes that play a central role in activating and detoxifying many xenobiotics and endogenous compounds thought to be involved in the development of several human diseases. Among other factors, individual susceptibility to developing these pathologies relies on genetic polymorphisms, which are related to ethnic differences, since the frequency of mutant genotypes varies in different populations. The aim of this study was to investigate the genetic basis of CYP2E1 polymorphisms in the populations of four different geographical locations of China. Twenty-two different CYP2E1 polymorphisms, including six novel variants in promoter regions and a novel nonsense mutation, were identified. The frequencies of some polymorphisms and genotypes demonstrated significant differences among the four populations. Linkage disequilibrium analysis and tag SNP selection were performed. Haplotypes were analyzed within the selected tag SNPs. Tag SNP selection and haplotype distributions showed differences across the four populations.     

Cytochrome P4502C9 (CYP2C9) allele frequencies in Canadian Native Indian and Inuit populations.

CYP2C9 is the major P450 2C enzyme in human liver and contributes to the metabolism of a number of clinically important substrate drugs. This polymorphically expressed enzyme has been studied in Caucasian, Asian, and to some extent in African American populations, but little is known about the genetic variation in Native American populations. We therefore determined the 2C9*2 (Arg144Cys) and 2C9*3 (Ile359Leu) allele frequencies in 153 Native Canadian Indian (CNI) and 151 Inuit subjects by PCR-RFLP techniques. We also present genotyping data for two reference populations, 325 Caucasian (white North American) and 102 Chinese subjects. Genotyping analysis did not reveal any 2C9*4 alleles in the CNI, Inuit, Caucasian, or Chinese individuals. The 2C9*2 allele appears to be absent in Chinese and Inuit populations, but was present in CNI and Caucasian subjects at frequencies of 0.03 and 0.08-0.15, respectively. The 2C9*3 allele was not detected in the Inuit group, but occured in the CNI group (f = 0.06) at a frequency comparable to that of other ethnic groups. This group of Inuit individuals are the first population in which no 2C9*2 or *3 alleles have been detected so far. Therefore, these alleles may be extremely rare or absent, and unless other novel polymorphisms exist in this Inuit group one would not anticipate any CYP2C9 poor metabolizer subjects among this population.     

中华蜜蜂细胞色素CYP9E2基因克隆及其表达分析

【目的】克隆中华蜜蜂Apis cerana cerana细胞色素CYP9E2基因的完整编码区序列,分析CYP9E2基因在工蜂体内的表达特征,为研究该基因的生物学功能提供理论基础。【方法】以解剖获得的中华蜜蜂采集蜂中肠组织为材料,提取总RNA。利用RT-PCR技术克隆中华蜜蜂CYP9E2基因的编码区。采用多种生物信息学软件分析该基因的核苷酸和氨基酸序列,利用荧光定量PCR技术(quantitative real-time PCR)分析其在中华蜜蜂工蜂成虫期不同阶段(初生蜂、哺育蜂、守卫蜂以及采集蜂)头部和中肠组织中的相对表达量及在饲喂氟氯苯菊酯后工蜂中肠组织中的表达变化。【结果】克隆获得中华蜜蜂CYP9E2基因(命名为Ac CYP9E2)mRNA序列,长度为1 600 bp(Gen Bank登录号:KX394629),编码区长1 494 bp,编码497个氨基酸,其蛋白质分子量为57.026k D,等电点为8.32。系统发育树显示,中华蜜蜂Ac CYP9E2与西方蜜蜂Apis mellifera、小蜜蜂Apis florea CYP9E2基因聚成一支。对中华蜜蜂工蜂成虫期不同阶段头部和中肠组织Ac CYP9E2相对表达量测定发现,该基因在中华蜜蜂工蜂成虫期不同阶段的表达量存在一定差异,其中,采集蜂头部和中肠组织中Ac CYP9E2相对表达量均显著高于初生蜂、哺育蜂以及守卫蜂(P0.05),而且4个阶段工蜂中肠组织中的Ac CYP9E2相对表达量均显著高于其头部(P0.05)。饲喂氟氯苯菊酯后,工蜂中肠组织中Ac CYP9E2的相对表达量显著高于对照组(P0.05)。【结论】推测Ac CYP9E2可能参与了中华蜜蜂机体外源物质的代谢与解毒过程。     

Insertional polymorphism of the CYP2E1 gene in infiltrative pulmonary tuberculosis in populations of Bashkortostan Republic

Insertion polymorphism Ins96 of the CYP2E1 promoter region was for the first time studied in three ethnic groups of Bashkortostan. Population-specific features of genotype and allele frequency distributions were observed. The CYP2E1 polymorphism was associated with infiltrative pulmonary tuberculosis in the Bashkortostan population.     

Ethnic differences in CYP2C9*2 (Arg144Cys) and CYP2C9*3 (Ile359Leu) genotypes in Japanese and Israeli populations

CYP2C9 is a major P450 2C enzyme, which hydroxylates about 16% of drugs that are in current clinical use and contributes to the metabolism of a number of clinically important substrate drugs such as warfarin. Ethnic differences in the genetic variation of CYP2C9 have been reported, and might be related to the frequencies of adverse reactions to drugs metabolized by CYP2C9 in different ethnic groups. In the present study, ethnic differences in the CYP2C9*2 and CYP2C9*3 allele distribution in Japanese and Israeli populations were evaluated using a newly developed oligonucleotide based DNA array (OligoArray(R)). The population studied consisted of 147 Japanese and 388 Israeli donors (100 Ashkenazi Jews, 99 Yemenite Jews, 100 Moroccan Jews and 89 Libyan Jews). The CYP2C9*2 [Arg144Cys (416 C>T), exon 3] and CYP2C9*3 [Ile359Leu (1061 A>C), exon 7] genotypes were determined using an OligoArray(R). The accuracy of genotyping by the OligoArray(R) was verified by the fluorescent dye-terminator cycle sequencing method. A Hardy-Weinberg test indicated equilibrium (chi(2)<3.84 is Hardy-Weinberg) in all populations. The CYP2C9*2 genotype (CC/CT+TT) was absent in Japanese (1/0) (OR 0.02), and its frequency was significant in Libyan Jews (0.697/0.303) (OR 2.13; 95% CI 1.07-4.24) compared with Ashkenazi Jews (0.83/0.17), Yemenite Jews (0.899/0.101), and Moroccan Jews (0.81/0.19). The frequencies of CYP2C9*3 genotype (AA/AC+CC) was significantly lower in Japanese (0.986/0.014) (OR 0.08), and was higher in Libyan Jews (0.652/0.348) (OR 3.03; 95% CI 1.5-6.1) and Moroccan Jews (0.77/0.23) (OR 1.69; 95% CI 0.62-3.48) compared with those in Ashkenazi Jews (0.85/0.15) and Yemenite Jews (0.849/0.151). Thus, the CYP2C9*2 (Arg144Cys) and CYP2C9*3 (Ile359Leu) variants were rare in the Japanese population, and showed different frequencies in the four Jewish ethnic groups examined.     

High-throughput screening assays for the assessment of CYP2C9*1, CYP2C9*2, and CYP2C9*3 metabolism using fluorogenic Vivid substrates

CYP2C9 is a genetically polymorphic human cytochrome P450 isozyme involved in the oxidative metabolism of many drugs, including nonsteroidal anti-inflammatory compounds. Individuals genotyped heterozygous or homozygous for CYP2C9 allelic variants have demonstrated altered metabolism of some drugs primarily metabolized by CYP2C9. The ability to expand screening of CYP2C9 allelic variants to a larger set of drugs and pharmaceutical agents would contribute to a better understanding of the significance of CYP2C9 polymorphisms in the population and to predictions of possible outcomes. The authors report the development of an in vitro fluorescence-based assay employing recombinant CYP2C9 variants (CYP2C9*1, CYP2C9*2, and CYP2C9*3) and fluorogenic Vivid(R) CYP2C9 substrates to explore the effects of CYP2C9 polymorphisms on drug metabolism, using drugs primarily metabolized by CYP2C9. Several chemically diverse fluorogenic substrates (Vivid(R) CYP2C9 blue, green, and red substrates) were used as prototypic probes to obtain in vitro CYP2C9 metabolic rates and kinetic parameters, such as apparent K(m), V(max), and V(max)/K(m) ratios for each allelic variant. In addition, a diverse panel of drugs was screened as assay modifiers with CYP2C9*1, CYP2C9*2, CYP2C9*3, and the fluorogenic Vivid(R) CYP2C9 substrates. The inhibitory potential of this large group of chemically diverse drugs and compounds has been assessed on the basis of their ability to compete with Vivid(R) CYP2C9 substrates in fluorescent reporter assays, thus providing a sensitive and quick assessment of polymorphism-dependent changes in CYP2C9 metabolism.