Analysis of human CYP1A1 and CYP1A2 genes and their shared bidirectional promoter in eight world populations

The human CYP1A1_CYP1A2 locus comprises the CYP1A1 (5,988 bp) and CYP1A2 (7,759 bp) transcribed regions, oriented head‐to‐head, sharing a bidirectional promoter of 23,306 bp. The older CYP1A1 gene appears more conserved and responsible for critical life function(s), whereas the younger CYP1A2 gene might have evolved more rapidly due to environmental (dietary) pressures. A population genetics study might confirm this premise. We combined 60 CYP1A1_CYP1A2 SNPs found in the present study (eight New Guinea Highlanders, eight Samoans, four Dogrib, four Teribe, four Pehuenche, and one Caucasian) with those found in a previous study (six West Africans, four Han Chinese, six Germans, four Samoans, and four Dogrib), yielding a total of 106 SNPs in 106 chromosomes. Resequencing of Oceanians plus Amerindians in the present study yielded 21 New World SNPs (～20%), of which 17 are not previously reported in any SNP database. Various tests revealed selective pressures for both genes and both haploblocks; unfortunately, differences in rates of evolution between the two genes were undetectable. Fay & Wu's H test revealed a “hitchhiking event” centered around four SNPs in the CYP1A1 3′‐UTR; a study in silico identified different microRNA‐binding patterns in the hitchhiked region, when the mutations were present compared with the mutations absent. Hum Mutat 30:1–14, 2009. © 2009 Wiley‐Liss, Inc.     

Evidence for Association of Polymorphisms in CYP2J2 and Susceptibility to Essential Hypertension

Objective Evidence from animal models and human studies suggests that CYP2J2 plays a mechanistic role in the development of hypertension. The present study aims to investigate the potential genetic contribution of the CYP2J2 gene to the etiology of essential hypertension (EH) and individual blood pressure.
Methods We selected eight polymorphisms in/or around the CYP2J2 gene and performed a case-control association study involving 841 Han Chinese subjects, including 415 unrelated hypertensives and 426 age-, gender- and area-matched normotensives.
Results Three functionally identified variants ( CYP2J2  *2, *7 and CYP2J2  *8) and SNP rs11572182 represented rare polymorphisms in Han Chinese. However, the difference in rs1155002 genotype distribution between hypertensive and healthy subjects was close to significance (P = 0.06) in the whole sample. Interestingly, significant evidence for an association with rs1155002 was found in females when stratified by gender. In females, the TT homozygote of rs1155002 seems to be a risk factor for hypertension (p = 0.014). In addition, ANOVA analysis suggested TT carriers had significantly higher systolic blood pressure (p = 0.016). The genotype frequencies for rs10493270, rs1180273 and rs1324491 revealed no statistically significant differences. Likewise, four-marker haplotype frequencies showed no significant differences between cases and controls.
Conclusion Our data provide strong evidence that the CYP2J2 gene is a susceptibility factor for essential hypertension, especially in females, and influences individual systolic blood pressure in the Chinese Han population.     

Association of VKORC1 and CYP2C9 polymorphisms with warfarin dose requirements in Japanese patients

Warfarin is the most commonly used oral anticoagulant for treatment of thromboembolism, but adjustment of the dose appropriate to each patient is not so easy because of the large inter-individual variation in dose requirement. We analyzed single nucleotide polymorphism (SNP) genotypes of the VKORC1 and CYP2C9 genes using DNA from 828 Japanese patients treated with warfarin, and investigated association between SNP genotype and warfarin-maintenance dose. Five SNPs in VKORC1, 5 flanking–1413A>G, intron 1–136T>C, intron 2+124C>G, intron 2+837T>C and exon 3 343G>A, were in absolute linkage disequilibrium, and showed a significant association with daily warfarin dose of these patients. The median warfarin dose of patients with homozygosity for the minor allele was 4.0 mg/day, which is significantly higher than those heterozygous for the minor allele (3.5 mg/day) or those homozygous for the major allele (2.5 mg/day; P=5.1×10^–11 in the case of intron 1–136T>C SNP). We then genotyped the CYP2C9 gene for the Japanese common genetic variant, CYP2C9*3 and, based on the genotype of these two genes, classified patients into three categories, which we call warfarin-responsive index. The median warfarin daily dose varied significantly in this classification according to the warfarin-responsive index (2.0 mg/day for index 0 group, 2.5 mg/day for index 1 group, and 3.5 mg/day for index 2 group; P=4.4×10^–13). Thus, analysis of the combination of VKORC1 and CYP2C9 genotypes should identify warfarin-sensitive patients who require a lower dose of drug, allowing personalized warfarin treatment.     

The high prevalence of the poor and ultrarapid metabolite alleles of CYP2D6, CYP2C9, CYP2C19, CYP3A4, and CYP3A5 in Taiwanese population

Genetic polymorphisms of drug metabolizing enzymes, such as cytochromes P450 (CYPs), play major roles in the variations of drug responsiveness in human. The aim of this study is to identify the high prevalence (minor allele frequencies >1%) of the abnormal metabolite alleles of CYP2C9, CYP2C19, CYP2D6, CYP3A4, and CYP3A5 in the Taiwanese population. The genotyping of the functional single nucleotide polymorphisms (SNPs) of CYPs were conducted by direct exon sequencing in 180 Taiwanese volunteers. Twenty-one unique SNPs including three newly identified SNPs were detected in the Taiwanese population. Six of the 21 SNPs in five genes showed frequencies more than 1%. The results indicated that it could be very useful and important in developing an inexpensive, convenient, and precise genotyping method for the high prevalence of CYPs metabolizing abnormal alleles in the Taiwanese population.     

CYP4A11基因多态性与心肌梗死相关

目的 研究在不同性别中CYP4A11基因多态性与心肌梗死的关系.方法 166例心肌梗死患者和158例对照组,选择CYPA11基因的3个SNPs(rs9332978、rs3890011和rs1126742),应用TaqMan SNP基因分型法进行基因分型,并应用病例对照的研究方法进行相关性分析.结果 rs3890011的基因分型在心肌梗死组和对照组之间的分布存在明显差异(P＜0.05),心肌梗死组携带GG基因型(GG vs CC+ GC)高于对照组(P＜0.05),在排除吸烟、高血压、糖尿病等混杂因素后,仍存在显著性差异(95％ CI:1.138～2.432,P＜0.01).结论 CYP4A11基因的rs3890011多态性与心肌梗死相关,rs3890011的GG基因型可作为心肌梗死易感基因标记.     

High resolution melting method to detect single nucleotide polymorphism of VKORC1 and CYP2C9

Single nucleotide polymorphisms (SNPs) of VKORC (1173T/C, rs9934438) and CYP2C9 (1075A/C, rs1057910) are major contributory factors on the sensitivity of warfarin in Chinese. Analysis of the two genomic loci could help warfarin treatment individual from bleeding or thrombosis events. An assay with the advantages of simplicity, speed, high sensitivity and low cost for genotyping is calling for clinical laboratories. High resolution method (HRM) meets these callings, but no study with large sample tested its performance in genotyping of rs9934438 and rs1057910. In this study, we identified polymorphisms of rs9934438 and rs1057910 in 255 unrelated Chinese heart valve replacement patients of Han ethnic group from West China Hospital. The two genomic loci were genotyped by HRM using LightCycler® 480 High Resolution Melting Master on LightCycler® 480 Real-Time PCR instruments (Roche Diagnostics), and all amplified PCR products were sent for direct DNA sequencing. The genotyping of rs1057910 between HRM and sequencing showed perfect 100% concordance. While the concordance of rs9934438 between HRM and sequencing was 99.2%. Unexpected mutation interfered genotyping results of HRM when genotyping rs9934438. HRM is a valuable technique for genotype detection of rs9934438 and rs1057910 to assess individual sensitivity to warfarin, where DNA sequencing is added inevitably sometimes.     

Association of two polymorphisms in the FADS1/FADS2 gene cluster and the risk of coronary artery disease and ischemic stroke

Little is known about the association of the FADS1/FADS2 SNPs and serum lipid levels and the risk of coronary artery disease (CAD) and ischemic stroke (IS) in the Chinese southern population. The present study aimed to determine such association in the Chinese southern population. A total of 1,669 unrelated subjects (CAD, 534; IS, 553; and healthy controls, 582) were recruited in the study. Genotypes of the FADS1 rs174546 SNP and the FADS2 rs174601 SNP were determined by the SNaPshot Multiplex Kit. The T allele and TT genotype frequencies of the two SNPs were predominant in our study population. The T alleles were associated with increased risk of CAD and IS. Correspondingly, the C alleles were associated with reduced risk of CAD and IS. Haplotype analyses showed that the haplotype of T-T (rs174546-rs174601) was associated with an increased risk for IS, and the haplotype of C-C (rs174546-rs174601) was associated with a reduced risk for CAD and IS. The two SNPs were likely to influence serum lipid levels. The T allele carriers of the two SNPs and rs174601 TT genotype were associated with decreased serum HDL-C and ApoAI levels in the patient groups and with an increased risk of CAD and IS. The present study suggests that the FADS1 rs174546 SNP and the FADS2 rs174601 SNP are associated with the risk of CAD and IS, and are likely to influence serum lipid levels. However, further functional studies are needed to clarify how the two SNPs actually affect serum lipid levels and the risk of CAD and IS.     

Genetic factors associated with patient-specific warfarin dose in ethnic Indonesians

Background

CYP2C9 and VKORC1 are two major genetic factors associated with inter-individual variability in warfarin dose. Additionally, genes in the warfarin metabolism pathway have also been associated with dose variance. We analyzed Single Nucleotide Polymorphisms (SNPs) in these genes to identify genetic factors that might confer warfarin sensitivity in Indonesian patients.

Methods

Direct sequencing method was used to identify SNPs in CYP2C9, VKORC1, CYP4F2, EPHX1, PROC and GGCX genes in warfarin-treated patients. Multiple linear regressions were performed to model the relationship warfarin daily dose requirement with genetic and non-genetic variables measured and used to develop a novel algorithm for warfarin dosing.

Results

From the 40 SNPs analyzed, CYP2C9 rs17847036 and VKORC1 rs9923231 showed significant association with warfarin sensitivity. In our study population, no significant correlation could be detected between CYP2C9*3, CYP2C9C-65 (rs9332127), CYP4F2 rs2108622, GGCX rs12714145, EPHX1 rs4653436 and PROC rs1799809 with warfarin sensitivity.

Conclusions

VKORC1 rs9923231 AA and CYP2C9 rs17847036 GG genotypes were associated with low dosage requirements of most patients (2.05 ± 0.77 mg/day and 2.09 ± 0.70 mg/day, respectively). CYP2C9 and VKORC1 genetic variants as well as non-genetic factors such as age, body weight and body height account for 15.4% of variance in warfarin dose among our study population. Additional analysis of this combination could allow for personalized warfarin treatment in ethnic Indonesians.

     

Polymorphisms in the VKORC1 gene are strongly associated with warfarin dosage requirements in patients receiving anticoagulation

Background

Warfarin is a mainstay of therapy for conditions associated with an increased risk of thromboembolic events. However, the use of this common agent is fraught with complications and little is known regarding inter‐individual variation in warfarin response.

Objective

We tested for association between single nucleotide polymorphisms (SNPs) in VKORC1 and CYP2C9 and average weekly warfarin dose required to maintain patients at their desired anticoagulation target.

Methods

The sample consisted of 93 European‐American patients from anticoagulation clinics at the University of North Carolina at Chapel Hill. Data on mean weekly warfarin dose were collected over a mean treatment period of 20.6 months. ANCOVA models were used and haplotype analysis was performed.

Results

Three of six VKORC1 SNPs were found to be very strongly associated with the average warfarin dose required to achieve the target international normalised ratio (INR; p<0.0001). The mean weekly dose by genotype ranged from approximately 27 to 47 mg. There was no evidence for an association between either of the two CYP2C9 polymorphisms studied, CYP2C9*2 and CYP2C9*3. CYP2C9*3 was significantly (p = 0.05) associated with average warfarin dosage after adjustment for VKORC1*1173.

Conclusions

These results are of considerable clinical interest and confirm recently published results regarding the role of these two genes in modifying warfarin metabolism and maintenance dosage. The consistent findings regarding the role of VKORC1 and CYP2C9 in warfarin metabolism and maintenance dosage represent a clinically useful proof of principal for the use of pharmacogenomic information in medicine and may lead to improved understanding of warfarin''s actions.     

Association of variants in CELSR2-PSRC1-SORT1 with risk of serum lipid traits,coronary artery disease and ischemic stroke

Recent genome-wide association studies (GWAS) have identified genetic variants associated with coronary artery disease (CAD), ischemic stroke (IS) and serum lipid traits in different ethnic groups. Some loci were found to affect the risk of CAD and IS. However, there were no data in the southern Chinese populations. Our study was to assess the association of CELSR2-PSRC1-SORT1 rs599839, rs464218 and rs6698443 SNPs and serum lipid levels and the risk of CAD and IS. The genotypes of 3 SNPs were detected in 561 CAD and 527 IS patients, and in 590 healthy controls. The genotypic and allelic frequencies of the rs599839 SNP were different between the controls and IS patients (P < 0.05). The minor G alleles of rs599839 and rs464218 SNPs were associated with higher high-density lipoprotein cholesterol concentrations in CAD and IS patients (P < 0.05); respectively. No association was found between the SNPs of rs599839, rs464218 and rs6698843 at the CELSR2-PSRC1-SORT1 and the risk of CAD or IS. These results will be replicated in the other Chinese populations.     

Confirmation of association between multiple sclerosis and CYP27B1

Multiple sclerosis, MS (OMIM No. 126200), is a complex inflammatory disease that is characterized by lesions in the central nervous system. Both genes and other environmental factors influence disease susceptibility. One of the environmental factors that has been implicated in MS and autoimmune disease, such as type 1 diabetes, is vitamin D deficiency, in which patients have lower levels of 25-hydroxyvitamin D3 (25-OHD₃) in blood than do controls. Previtamin D₃ is produced in the skin, and turned into 25-OHD₃ in the liver. In the kidney, skin and immune cells, 25-OHD₃ is turned into bioactive 1,25(OH)₂D₃ by the enzyme coded by CYP27B1 (cytochrome P450 family 27 subfamily B peptide 1) on chromosome 12q13.1–3. 1,25(OH)₂D₃ binds to the vitamin D receptor, expressed in T cells and antigen-presenting cells. 1,25(OH)₂D₃ has a suppressive role in the adaptive immune system, decreasing T-cell and dendritic cell maturation, proliferation and differentiation, shifting the balance between T-helper 1 (Th1) and Th2 cells in favor of Th2 cells and increasing the suppressive function of regulatory T cells. Rs703842 in the 12q13–14 region was associated with MS in a recent study by the Australian and New Zealand Multiple Sclerosis Genetics Consortium (ANZgene). We show associations with three SNPs in this region in our Swedish materials (2158 cases, 1759 controls) rs4646536, rs10877012 and rs10877015 (P=0.01, 0.01 and 3.5 × 10⁻³, respectively). We imputed rs703842 SNP and performed a joint analysis with the ANZgene results, reaching a significant association for rs703842 (P=5.1 × 10⁻¹¹; odds ratio 0.83; 95% confidence interval 0.79–0.88). Owing to its close association with 25-OHD₃, our results lend further support to the role of vitamin D in MS pathology.     

IGF2, LEPR,POMC, PPARG,and PPARGC1 gene variants are associated with obesity-related risk phenotypes in Brazilian children and adolescents

Association studies of genetic variants and obesity and/or obesity-related risk factors have yielded contradictory results. The aim of the present study was to determine the possible association of five single-nucleotide polymorphisms (SNPs) located in the IGF2, LEPR, POMC, PPARG, and PPARGC1genes with obesity or obesity-related risk phenotypes. This case-control study assessed overweight (n=192) and normal-weight (n=211) children and adolescents. The SNPs were analyzed using minisequencing assays, and variables and genotype distributions between the groups were compared using one-way analysis of variance and Pearson''s chi-square or Fisher''s exact tests. Logistic regression analysis adjusted for age and gender was used to calculate the odds ratios (ORs) for selected phenotype risks in each group. No difference in SNP distribution was observed between groups. In children, POMC rs28932472(C) was associated with lower diastolic blood pressure (P=0.001), higher low-density lipoprotein (LDL) cholesterol (P=0.014), and higher risk in overweight children of altered total cholesterol (OR=7.35, P=0.006). In adolescents, IGF2 rs680(A) was associated with higher glucose (P=0.012) and higher risk in overweight adolescents for altered insulin (OR=10.08, P=0.005) and homeostasis model of insulin resistance (HOMA-IR) (OR=6.34, P=0.010). PPARG rs1801282(G) conferred a higher risk of altered insulin (OR=12.31, P=0.003), and HOMA-IR (OR=7.47, P=0.005) in overweight adolescents. PARGC1 rs8192678(A) was associated with higher triacylglycerols (P=0.005), and LEPR rs1137101(A) was marginally associated with higher LDL cholesterol (P=0.017). LEPR rs1137101(A) conferred higher risk for altered insulin, and HOMA-IR in overweight adolescents. The associations observed in this population suggested increased risk for cardiovascular diseases and/or type 2 diabetes later in life for individuals carrying these alleles.     

Structural variation at the CYP2C locus: Characterization of deletion and duplication alleles

The human CYP2C locus harbors the polymorphic CYP2C18, CYP2C19, CYP2C9, and CYP2C8 genes, and of these, CYP2C19 and CYP2C9 are directly involved in the metabolism of ~15% of all medications. All variant CYP2C19 and CYP2C9 star (*) allele haplotypes currently cataloged by the Pharmacogene Variation (PharmVar) Consortium are defined by sequence variants. To determine if structural variation also occurs at the CYP2C locus, the 10q23.33 region was interrogated across deidentified clinical chromosomal microarray (CMA) data from 20,642 patients tested at two academic medical centers. Fourteen copy number variants that affected the coding region of CYP2C genes were detected in the clinical CMA cohorts, which ranged in size from 39.2 to 1,043.3 kb. Selected deletions and duplications were confirmed by MLPA or ddPCR. Analysis of the clinical CMA and an additional 78,839 cases from the Database of Genomic Variants (DGV) and ClinGen (total n = 99,481) indicated that the carrier frequency of a CYP2C structural variant is ~1 in 1,000, with ~1 in 2,000 being a CYP2C19 full gene or partial‐gene deletion carrier, designated by PharmVar as CYP2C19*36 and *37, respectively. Although these structural variants are rare in the general population, their detection will likely improve metabolizer phenotype prediction when interrogated for research and/or clinical testing.     

Association of CYP2C19*2 and *3 Genetic Variants with Essential Hypertension in Koreans

Purpose

The cytochrome P450 2C19 (CYP2C19) metabolizes arachidonic acid to produce epoxyicosanoid acids, which are involved in vascular tone and regulation of blood pressure. Recent findings suggest that CYP2C19 gene might be considered as a novel candidate gene for treatment of cardiovascular disease. The aim of the present study was to evaluate the association between two variants, CYP2C19^*2 (681G>A) and CYP2C19^*3 (636G>A) and the development of essential hypertension (EH) in Koreans.

Materials and Methods

We carried out an association study in a total of 1190 individuals (527 hypertensive subjects and 663 unrelated healthy controls). The CYP2C19 polymorphisms were genotyped using the SNaPShot™ assay.

Results

The distribution of alleles and genotypes of CYP2C19^*3 showed significant difference between hypertensive patients and normal controls (p=0.011 and p=0.013, respectively). Logistic regression analysis indicated that the CYP2C19^*3 (636A) allele carriers were significantly associated with EH [odds ratio, 0.691; 95% confidence interval (CI), 0.512-0.932, p=0.016], in comparison to wild type homozygotes (CYP2C19^*1/^*1). Neither genotype nor allele distribution of CYP2C19^*2 polymorphism showed significant differences between hypertensive and control groups (p>0.05).

Conclusion

Our present findings strengthen the evidence of an association between CYP2C19 gene polymorphism and EH prevalence. In particular, the CYP2C19^*3 defective allele may contribute to reduced risk for the development of EH.     

Effects of FTO and PPARγ variants on intrauterine growth restriction in a Brazilian birth cohort

Intrauterine growth restriction (IUGR) is related to a higher risk of neonatal mortality, minor cognitive deficit, metabolic syndrome, and cardiovascular disease in adulthood. In previous studies, genetic variants in the FTO (fat mass and obesity-associated) and PPARγ (peroxisome proliferator-activated receptor-gamma) genes have been associated with metabolic disease, body mass index, and obesity among other outcomes. We studied the association of selected FTO (rs1421085, rs55682395, rs17817449, rs8043757, rs9926289, and rs9939609) and PPARγ (rs10865710, rs17036263, rs35206526, rs1801282, rs28763894, rs41516544, rs62243567, rs3856806, and rs1805151) single-nucleotide polymorphisms (SNPs) with IUGR, through a case-control study in a cohort of live births that occurred from June 1978 to May 1979 in a Brazilian city. We selected 280 IUGR cases and 256 controls for analysis. Logistic regression was used to jointly analyze the SNPs as well as factors such as maternal smoking, age, and schooling. We found that the PPARγ rs41516544 increased the risk of IUGR for male offspring (OR 27.83, 95%CI 3.65-212.32) as well as for female offspring (OR=8.94, 95%CI: 1.96-40.88). The FTO rs9939609 TA genotype resulted in a reduced susceptibility to IUGR for male offspring only (OR=0.47, 95%CI: 0.26-0.86). In conclusion, we demonstrated that PPARγ SNP had a positive effect and FTO SNP had a negative effect on IUGR occurrence, and these effects were gender-specific.     

Association of rs10490924 in ARMS2/HTRA1 with age‐related macular degeneration in the Pakistani population

Age‐related macular degeneration (AMD) is a disease of the elderly in which central vision is lost because of degenerative changes of the macula. The current study investigated the association of single‐nucleotide polymorphisms (SNPs) with AMD in the Pakistani population. Four SNPs were analyzed in this study: rs1061170 in the CFH, rs429608 near CFB, rs2230199 in the C3, and rs10490924 in ARMS2/HTRA1. This case‐control association study was conducted on 300 AMD patients (125 wet AMD and 175 dry AMD) and 200 unaffected age‐ and gender‐matched control individuals. The association of the SNP genotypes and allele frequency distributions were compared between patients and healthy controls, keeping age, gender, and smoking status as covariates. A significant genotype and variant allele association was found of rs10490924 in ARMS2/HTRA1 with wet AMD, while the SNPs in CFH, CFB, and C3 were not associated with AMD in the current Pakistani cohort. The lack of association of CFH, CFB, and C3 may be attributed to limited sample size. This study demonstrates that genetic causative factors of AMD differ among populations and supports the need for genetic association studies among cohorts from various populations to increase our global understanding of the disease pathogenesis.     

Genetic polymorphism of CYP3A4 is associated with poor response to ifosfamide treatment in children with solid embryonic tumors

IntroductionThe CYP450 complex participates in the metabolism of ifosfamide, an antineoplastic drug used to treat solid tumors. CYP450 genes contain several single nucleotide polymorphisms (SNPs) that confer different activity towards the enzyme. The aim of our study was to analyze gene frequencies of allelic variants and their association with ifosfamide blood levels and patient prognosis.Material and methods148 DNA samples from children were analyzed. Genotyping was performed by real-time PCR with TaqMan probes and ifosfamide levels were determined in dried blood drop by UPLCMS/MS.ResultsIfosfamide levels increased according to the genotype, and patients with the variant rs1799853 in CYP2C9 genotype CC had lower levels of ifosfamide (median = 1.8 μmol/l, Q₂₅ 0.9–Q₇₅ 4.6) compared with patients with genotype TT + CT (median = 2.8 μmol/l, Q₂₅ 1.9–Q₇₅ 5.1), p < 0.001. In the case of the rs2740574 variant in the CYP3A4 gene, patients with normal genotype (TT) presented median = 1.4 μmol/l, (Q₂₅ 0.7–Q₇₅ 2.7), while patients with the CC + TC genotype had higher levels of ifosfamide (median = 2.0 μmol/l, Q₂₅ 1.0–Q₇₅ 4.3), p = 0.024. In addition, patients with CC + CT genotype of this variant had a higher risk of non-response to treatment compared to patients with TT genotype (RR = 1.3, 95% CI: 1.07–1.59, p = 0.03).ConclusionsPolymorphisms in CYP2C9 and CYP3A4 genes are associated with high levels of ifosfamide. In addition, the polymorphism rs2740574 in CYP3A4 was associated with a worse therapeutic response.     

Toward the evaluation of function in genetic variability: characterizing human SNP frequencies and establishing BAC-transgenic mice carrying the human CYP1A1_CYP1A2 locus

Interindividual differences in human CYP1A1 and CYP1A2 expression appear to be associated with variability in risk toward various types of environmental toxicity and cancer. These two genes are oriented head-to-head on human chromosome 15; the 23.3-kb spacer region might contain distinct regulatory regions for CYP1A1 and distinct regulatory regions for CYP1A2, or the regulatory regions for the two genes might overlap one another. From 24 unrelated subjects of five major, geographically-isolated subgroups, we resequenced both genes (all exons and all introns) plus some 3' flanking sequences and the entire spacer region (39.6 kb total); 85 SNPs were found, 49 of which were not currently in the National Center for Biotechnology Information (NCBI) database. Of the 57 double-hit SNPs, we carried out SNP-typing in 94 Africans, 96 Asians, and 83 Caucasians and found striking ethnic differences in SNP frequencies and haplotype evolution; the two CYP1A1 SNPs and the one CYP1A2 SNP that are most commonly used in epidemiological studies were shown not to be representative haplotype tag SNPs across these three human subgroups. Four BAC-transgenic mouse lines, carrying the human CYP1A2 and 15,190 bp of 5' flank, expressed only negligible basal or inducible CYP1A2 mRNA. A fifth BAC-transgenic mouse line, carrying both the human CYP1A1 and CYP1A2 genes and ample amounts of 3' flanking sequences, plus all of the spacer region--in the absence of the mouse Cyp1a1 or Cyp1a2 genes--expressed the human CYP1A1 and CYP1A2 mRNA, protein and enzyme activities in liver and nonhepatic tissues very similar to that of the mouse. Comparison of this hCYP1A1_1A2 transgenic line with hCYP1A1_1A2 lines carrying other common human haplotypes will enable us to evaluate function in human CYP1A1_CYP1A2 locus variability, with regard to toxicity and cancer caused by combustion products.