Single Nucleotide Polymorphisms In CYP2C9 Research Articles

Association of VKORC1 and CYP2C9 single-nucleotide polymorphisms with warfarin dose adjustment in Saudi patients.

Despite its wide usage, warfarin therapy remains challenging due to its narrow therapeutic index, inter-individual response variability, and risk of bleeding. Previous reports have suggested that polymorphisms in VKORC1 and CYP2C9 genes could influence warfarin therapy. Herein, we investigated whether VKORC1-1173C>T, CYP2C9*2, and CYP2C9*3 gene polymorphisms are associated with warfarin dose adjustment and related bleeding events. This cross-sectional study was conducted on Saudi adults receiving warfarin for more than 1month. Their demographics and relevant clinical data were obtained. Genotyping for VKORC1-1173C>T, CYP2C9*2, and CYP2C9*2 genotypes was performed. Patients who are homozygous for the mutant T allele VKORC1 T/T required the lowest warfarin daily maintenance dose, compared to VKORC1 C/T and VKORC1 C/C. Similarly, there was a significant reduction in warfarin daily maintenance dose among CYP2C9*1/*3 and CYP2C9*1/*2 groups compared to CYP2C9*1/*1. However, we found no significant correlation between the studied polymorphisms and warfarin-associated bleeding. Similar to other populations, the VKORC1 and CYP2C9 gene polymorphisms are significantly associated with warfarin dosage in Saudi patients. The presence of at least one copy of the mutant alleles for VKORC1-1173C>T, CYP2C9*2, and CYP2C9*3 is associated with a significant reduction in warfarin maintenance dose.

Assessment of susceptibility to phthalate and DINCH exposure through CYP and UGT single nucleotide polymorphisms

Single nucleotide polymorphisms (SNPs) of cytochrome P450 (CYPs) and UDP-glucuronosyltransferase (UGTs) genes have been proposed to influence phthalates and 1,2-cyclo-hexanedicarboxylic acid diisononyl ester (DINCH) biotransformation but have not been investigated on a populational level. We investigated the role of SNPs in CYP2C9, CYP2C19, CYP2D6, UGT2B15, and UGT1A7 genes in the biotransformation of phthalates (DEHP, DEP, DiBP, DnBP, BBzP, DiNP, DidP) and DINCH by determining their urine metabolites. From the Slovenian study population of 274 men and 289 lactating primiparous women we obtained data on phthalate and DINCH urine metabolite levels (MEHP, 5OH-MEHP, 5oxo-MEHP, 5cx-MEPP, MEP, MiBP, MnBP, MBzP, cx-MINP, OH-MiDP, MCHP, MnPeP, MnOP, 5OH-MINCH, 5oxo-MINCH), SNP genotypes (rs1057910=CYP2C9*3, rs1799853=CYP2C9*2, rs4244285=CYP2C19*2, rs12248560=CYP2C19*17, rs3892097=CYP2D6*4, rs1902023=UGT2B15*2, and rs11692021=UGT1A7*3) and questionnaires. Associations of SNPs with levels of metabolites and their ratios were assessed by multiple linear regression and ordinary logistic regression analyses. Significant associations were observed for CYP2C9*2, CYP2C9*3, CYP2C19*17, and UGT1A7*3 SNPs. The most pronounced was the influence of CYP2C9*2 and *3 on the reduced DEHP biotransformation, with lower levels of metabolites and their ratios in men and women. In contrast, carriers of CYP2C19*17 showed higher urine levels of DEHP metabolites in both genders, and in women also in higher DiNP, DiDP, and DINCH metabolite levels. The presence of UGT1A7*3 was associated with increased metabolite levels of DINCH in men and of DiBP and DBzP in women. Statistical models explained up to 27% of variability in metabolite levels or their ratios. Our observations confirm the effect of CYP2C9*2 and *3 SNPs towards reduced DEHP biotransformation. We show that CYP2C9*2, CYP2C9*3, CYP2C19*17, and UGT1A7*3 SNPs might represent biomarkers of susceptibility or resilience in phthalates and DINCH exposure that have been so far unrecognised.

Pharmacogenetics of warfarin dosing in patients of African and European ancestry.

Despite the introduction of direct acting oral anticoagulants, warfarin remains the most commonly prescribed oral anticoagulant. However, warfarin therapy is plagued by the large inter- and intrapatient variability. The variability in dosing fueled research to identify clinical and genetic predictors and develop more accurate dosing algorithms. Observational studies have demonstrated the significant impact of single nucleotide polymorphisms in CYP2C9 and VKORC1 on warfarin dose in patients of European ancestry and African-Americans. This evidence supported the design and conduct of clinical trials to assess whether genotype-guided dosing results in improved anticoagulation control and outcomes. The trial results have shown discordance by race, with pharmacogenetic algorithms improving dose and anticoagulation control among European ancestry patients compared with African-American patients. Herein, we review the evidence from observational and interventional studies, highlight the need for inclusion of minority race groups and propose the need to develop race specific dosing algorithms.

Effects of polymorphic variation on the thermostability of heterogenous populations of CYP3A4 and CYP2C9 enzymes in solution

The effect of non-synonymous single nucleotide polymorphisms (SNPs) on cytochrome P450 (CYP450) drug metabolism is currently poorly understood due to the large number of polymorphisms, the diversity of potential substrates and the complexity of CYP450 function. Previously we carried out in silico studies to explore the effect of SNPs on CYP450 function, using in silico calculations to predict the effect of mutations on protein stability. Here we have determined the effect of eight CYP3A4 and seven CYP2C9 SNPs on the thermostability of proteins in solution to test these predictions. Thermostability assays revealed distinct CYP450 sub-populations with only 65–70% of wild-type CYP3A4 and CYP2C9 susceptible to rapid heat-induced P450 to P420 conversion. CYP3A4 mutations G56D, P218R, S222P, I223R, L373F and M445T and CYP2C9 mutations V76M, I359L and I359T were destabilising, increasing the proportion of protein sensitive to the rapid heat-induced P450 to P420 conversion and/or reducing the half-life of this conversion. CYP2C9 Q214L was the only stabilising mutation. These results corresponded well with the in silico protein stability calculations, confirming the value of these predictions and together suggest that the changes in thermostability result from destabilisation/stabilisation of the protein fold, changes in the haem-binding environment or effects on oligomer formation/conformation.

Effect of CYP2C9, VKORC1, CYP4F2, and GGCX gene variants and patient characteristics on acenocoumarol maintenance dose: Proposal for a dosing algorithm for Moroccan patients.

We investigated the impact of non-genetics factors, and single nucleotide polymorphisms (SNPs) in VKORC1, CYP2C9, CYP4F2, and GGCX on acenocoumarol dosage in Moroccan adult's patients, in order to develop an algorithm to predict acenocoumarol dose for Moroccan patients. Our study consisted of 217 Moroccan patients taking a maintenance dose of acenocoumarol for various indications. The patients were genotyped for VKORC1 -1639 G>A, VKORC1 1173 C>T, CYP2C9*2, CYP2C9*3, CYP4F2 1347 G>A and GGCX 12970 C>G SNPs. The statistical analysis was performed using the SPSS software. The age and SNPs in VKORC1 and CYP2C9 were significantly associated with the weekly acenocoumarol dose requirement (p = 0.023, p = 0.0001 and p = 0.001 respectively). There was no association found between the weekly acenocoumarol dose and the CYP4F2 or GGCX variants (p-value > 0.05). Non-parametric analysis confirmed the accumulate effect of variant alleles at VKORC1 -1639 G>A, VKORC1 1173 C>T and CYP2C9 SNPs on the acenocoumarol dose requirement. With 90.24% less dose required for one patient carrying homozygote variant at VKORC1 -1173 (TT) and CYP2C9 *x/*x haplotype. The multiple linear regression analysis showed that mutation in VKORC1 -1639, VKORC1 1173 SNPs, or in CYP2C9 haplotype reduces the mean acenocoumarol weekly dose to 25.4%, 23.4% and 6.2%, respectively. The R2 for multiple regression analysis final model was found to be 35.9%. In this work we were able to establish the factors influencing interindividual sensitivity to the anticoagulant therapy that can help physicians to predict optimal dose requirement for long term therapy.

Polymorphisms in CYP2C9 are associated with response to indomethacin among neonates with patent ductus arteriosus.

BackgroundPatent ductus arteriosus (PDA) is a common complication seen in preterm infants. Indomethacin is routinely used to treat PDA. Evidence suggests that the response of indomethacin is highly heritable. This study investigated the association between single-nucleotide polymorphisms (SNPs) in CYP2C9 and the closure of PDA in response to indomethacin.MethodsSix SNPs in CYP2C9 were analyzed for association with indomethacin response. A case-control analysis was performed among neonates who responded to indomethacin (responders) and among those who required surgical ligation (non-responders). Independent transmission disequilibrium tests were performed among parent-child trios of responders and non-responders.ResultsThe G allele of rs2153628 was associated with increased odds of response to indomethacin in the case-control analysis (odds ratios (OR): 1.918, 95% confidence interval (CI): 1.056, 3.483). Among indomethacin responders, the G allele of rs2153628 and the T allele of rs1799853 were overtransmitted from the parents to their child (OR: 2.667, 95% CI: 1.374, 5.177 and OR: 2.375, 95% CI: 1.040, 5.425, respectively), consistent with the case-control analysis.ConclusionWe identified an association between two SNPs in CYP2C9, rs2153628 and rs1799853, and indomethacin response for the treatment of PDA. These findings suggest that response to indomethacin in the closure of PDA may be influenced by polymorphisms associated with altered indomethacin metabolism.

Association of Genetic Polymorphisms in the VKORC1 and CYP2C9 Genes with Warfarin Dosage in a Group of Kuwaiti Individuals

Warfarin is the most widely prescribed oral anticoagulant worldwide. The narrow therapeutic index and the large variation in the inter-individual dose of warfarin are problematic, since the side effects can be lethal. Single nucleotide polymorphisms (SNP) in CYP2C9 and VKORC1 have been shown to significantly affect warfarin dosage toleration and this effect varies among different populations. We aimed to investigate the effect of these SNPs on warfarin dosage in a sample of Kuwaiti patients. Kuwaiti patients who were taking a maintenance dose of warfarin were genotyped for CYP2C9*1, *2 and *3 and VKORC1 rs9923231, rs9934438, rs7294 and rs2884737. The association of these SNPs with the warfarin dose was evaluated. For CYP2C9, the CYP2C9 *1/*1 genotype required a higher dose (5.5 ± 3.3 mg/day) compared to non-*1/*1 (3.3 ± 1.7 mg/day) (p = 0.003). For VKORC1, the daily warfarin dose was significantly different (p = 0.001) among the three genotypes of rs9923231, rs9934438 and rs2884737, with carriers of the wild-type genotype requiring the highest dose compared to variant allele carriers (p ≤ 0.001-0.002). There was no association found between the daily warfarin dose and the rs7294 polymorphism. Our data showed that individuals carrying the wild-type allele of CYP2C9 or VKORC1 rs9923231, rs9934438 or rs2884737 are less sensitive than individuals with the variant alleles of these SNPs and therefore required a higher daily maintenance dose of warfarin. Our study confirms the association between SNPs in CYP2C9 and VKORC1 and warfarin dose tolerance in Kuwaiti patients.

VKORC1 and CYP2C9 Genotype Variations in Relation to Warfarin Dosing in Korean Stroke Patients

Background and PurposeVariant alleles of CYP2C9 and VKORC1 account for differences in anticoagulation response. We sought to establish a warfarin dosing formula for individualized target International Normalization Ratio of Prothrombin Times (INRs) using data from single nucleotide polymorphisms (SNPs) in VKORC1 and CYP2C9 in Korean patients.MethodsIschemic stroke patients displaying stable target INR for at least 3 months before enrollment were analyzed. Warfarin and vitamin K levels were measured to adjust for confounders. Phenotypes were defined using the 'warfarin response index' (WRI) defined as INR divided by the daily maintenance warfarin dose. We tested SNPs in CYP2C9 (3 sites: 430C>T (rs1799853), 1075A>C (rs1057910), 1076T>C) and VKORC1 (14 sites: 381C>T, 861C>A (rs17880887), 2653G>C, 3673A>G, 5496G>T, 5808T>G (r17882154), 6009C>T, 6484T>C (rs9934438), 6853C>T (rs17886369), 7566T>C, 8767G>C, 8814T>C, 9041G>A (rs17880624), and 9071G>T) using a standard sequencing method. Multivariate linear regression analysis was applied to establish the formula for warfarin dosage.ResultsAll 204 patients had excellent drug compliance. The mean INR was 2.22 (+0.56) and mean daily maintenance dose of warfarin was 3.92 mg (+1.54). Patients with low WRI were younger (P<0.001) with high body mass index (P=0.003), high prevalence of wild-type CYP2C9 polymorphism (1075A>C, P<0.001), and six heterozygote SNPs in VRORC1 (P<0.001), which were tightly interlinked (381T>C, 3673G>A, 6484T>C, 6853C>G. 7566C>T, 9041G>A) (r2=1). Based on these data, a warfarin dosing formula was established.ConclusionsWRI is influenced by age, body mass index and SNPs in VKORC1 and CYP2C9 in Korean stroke patients. The obtained warfarin dosing formula may be clinically applicable.

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

BackgroundCYP2C9 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.MethodsDirect 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.ResultsFrom 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.ConclusionsVKORC1 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.

A haplotype of CYP2C9 associated with warfarin sensitivity in mechanical heart valve replacement patients

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT * CYP2C9 single nucleotide polymorphisms (SNPs) are important in safe and effective oral anticoagulation with warfarin use. * Although CYP2C9*2 and *3 are important genetic factors for the warfarin dose, one of the CYP2C9 SNPs, IVS-65G>C, has been suggested to be associated with warfarin sensitivity. However, as of yet, there has been no explanation about the possible mechanism and linkage analysis. WHAT THIS PAPER ADDS * New information on CYP2C9 SNPs and their occurrences in common haplotype structures in healthy unrelated Koreans and in individuals who require low warfarin dose after mechanical heart valve replacements (MHVRs) were studied. * Additional evidence showed that an Asian dominant haplotype consisting of -1565C>T, -1188T>C, IVS3+197G>A, IVS3-334C>T, IVS3-65G>C, IVS4-115A>G and IVS5-73A>G could be associated with a low warfarin maintenance dose in mechanical heart valve replacement (MHVR) patients. AIMS The objectives of this study were to determine the distribution of CYP2C9 variants in Koreans and investigate their association with warfarin dose requirements in patients who received MHVRs. METHODS All nine exons, intron-exon junction, and promoter region of CYP2C9 were amplified and directly sequenced in 50 healthy normal Koreans. Additional direct DNA sequencing of the CYP2C9 gene was conducted in 36 of the 267 MHVR patients who required low maintenance warfarin doses without carrying CYP2C9*3 and VKORC1 1173T mutations. The effects of CYP2C9 genetics on warfarin maintenance dose were assessed in 267 MHVR patients. RESULTS Thirty-nine single nucleotide polymorphisms (SNPs) including seven previously unidentified SNPs were identified in 50 Koreans by direct DNA sequencing. One of the CYP2C9 haplotypes exhibited an association with warfarin low dose requirement. The adjusted odds ratio for the haplotype between the low dose group and the normal subjects was 2.5 (95% confidence interval 1.05, 6.16). This haplotype consisting of -1565C>T, -1188T>C, IVS3+197G>A, IVS3-334C>T, IVS3-65G>C, IVS4-115A>G, and IVS5-73A>G was found in 15% of 36 MHVR patients who required low warfarin doses, while 4% of 50 normal healthy subjects exhibited this haplotype. One of the SNPs comprising this haplotype, -1565C>T, apparently changed a protein binding pattern as observed in electrophoretic mobility shift assay. CONCLUSION The haplotype including -1565C>T, -1188T>C, IVS3+197G>A, IVS3-334C>T, IVS3-65G>C, IVS4-115A>G, and IVS5-73A>G seems to be associated with low warfarin dose requirement and this haplotype could be considered in the development of a warfarin dose prediction model for Asian populations.

CYP2C9 genotype and pharmacodynamic responses to losartan in patients with primary and secondary kidney diseases

Losartan is used for anti-proteinuric as well as blood pressure effects in chronic kidney disease (CKD). It is metabolized by cytochrome P450 (CYP) 2C9 to active E-3174. Single nucleotide polymorphisms in CYP2C9 that reduce catalytic activity could reduce clinical benefits. The study aims were to determine whether CYP2C9 variant alleles (*2 and *3) altered urinary protein excretion, glomerular filtration rate, and blood pressure in Caucasian patients prescribed losartan. Differences between baseline and 6-month follow-up outcomes were compared by CYP2C9 genotypes in 59 patients using unpaired t test or Mann-Whitney U test. Primary renal disease patients had a trend toward less favorable antiproteinuric response (-31.7 +/- 156 vs. -125 +/- 323%; p = 0.123) when carrying variant alleles. Patients with secondary renal diseases had less favorable diastolic blood pressure (9.8 +/- 16.0 vs. -3.2 +/- 10.6 mmHg; p = 0.043) and systolic blood pressure (16.2 +/- 27.1 vs. -5.5 +/- 17.5 mmHg; p = 0.044) with CYP2C9 variants. These preliminary results suggest a possible influence of CYP2C9 genotype on proteinuria and blood pressure in Caucasian CKD patients treated with losartan.