VKORC1-1639 G/A、CYP2C93*基因多态性对华法林使用剂量的影响

目的 基于VKORC1-1639 G/A及CYP2C93^*的基因多态性初步探讨华法林的使用剂量。方法 收集2016年10月-2018年2月进行华法林用药指导相关基因检测的100例患者,记录患者基本信息（身高、体质量等）。采用数字荧光分子杂交检测VKORC1-1639 G/A,CYP2C93^*的基因型分布,并结合患者年龄、身高、体质量等,根据国际华法林药物基因组学联合会（IWPC）公式计算患者华法林理论剂量。结果 VKORC1-1639 G/A AA、AG、GG基因型实际频率分别为84%,15%,1%;等位基因A,G频率分别为91.5%,8.5%。CYP2C9 3^* AA型、AC型、CC型实际频数分别为91%,9%,0%;等位基因A,C频率分别为95.5%,4.5%。不同VKORC1-1639 G/A、CYP2C93^*基因型华法林理论用量不同,VKORC1-1639 G/A AA型并CYP2C93^* AA型和VKORC1-1639 G/A AG型并CYP2C93^* AA型患者华法林剂量均高于VKORC1-1639 G/A AA型并CYP2C93^* AC型患者;VKORC1-1639 G/A AG型并CYP2C93^* AA型患者华法林用量高于VKORC1-1639 G/A AA型并CYP2C93^* AA型患者,3组间两两比较,差异有统计学意义（P<0.05）。结论 华法林代谢相关基因的基因多态性为VKORC1-1639 G/A AA及CYP2C93^* AA型占多数,表明VKORC1-1639 G/A基因突变率高,CYP2C93^*基因突变率较低,且两者多态性影响个体间华法林的理论剂量。     

CYP2C9 VKORC1基因多态性指导对非瓣膜性心房颤动患者华法林剂量的影响

目的 探讨CYP2C9、VKORC1基因多态性对非瓣膜性心房颤动（NVAF）患者华法林应用剂量的影响。方法 选择合肥市第二人民医院2017年11月至2019年10月收治的214例NVAF患者,采用随机数字表法分为基因指导组（69例）与对照组（145例）,基因指导组检测VKORC1、CYP2C9基因多态性,对照组按常规剂量给予华法林,比较两组患者华法林起效剂量、有效剂量、起效时间及第14、21天达稳定剂量患者比例等指标。结果 基因指导组患者在华法林应用初始剂量为（1.67±1.63）mg、稳定剂量为（2.02±0.94）mg,均低于对照组,起效时间为（7.62±2.87）d,短于对照组短,差异有统计学意义（P<0.05）。CYP2C9、VKORC1组华法林应用初始剂量、稳定剂量均低于对照组,起效时间短于对照组,差异有统计学意义（P<0.05）。基因指导组第14、21天达稳定剂量患者比例（76.44%、98.27%）高于对照组,差异有统计学意义（P<0.05）。结论 VKORC1、CYP2C9基因多态性检测结合NVAF患者临床特点可为临床精准合理应用华法林提供参考。     

CYP2C9和VKORC1基因多态性对老年房颤患者华法林稳定剂量影响及分析

摘要：目的:探讨CYP2C9和VKORC1基因多态性对老年房颤患者华法林稳定剂量的影响,建立适合汉族人群老年房颤患者的华法林给药模型,指导华法林个体化抗凝治疗。方法:对195例口服华法林抗凝的老年患者进行CYP2C9和VKORC1基因分型,比较不同基因型房颤老年患者华法林日均稳定剂量差异。采用多重线性回归分析法依据CYP2C9和VKORC1基因型、年龄、体表面积（BSA）、胺碘酮建立华法林稳定剂量计算公式。结果:国际标准化比值（INR）稳定在2.0～3.0之间时,CYP2C9*1/*1基因型患者日均华法林剂量（3.10±0.91） mg,显著高于CYP2C9*1/*3与CYP2C9*3/*3基因型患者的（2.10±0.89） mg和（1.25±0.00） mg; VKORC1-1639AA基因型患者日均华法林剂量（2.86±0.88） mg,显著低于VKORC1-1639GA/GG基因型患者的（3.68±0.88） mg和（6.38±0.91） mg（P<0.05）。通过多元线性回归分析得出华法林稳定剂量公式,建立的回归模型中包含年龄、BSA、胺碘酮、CYP2C9和VKORC1-1639基因型,该模型能解释约60.4%个体间华法林剂量差异。结论:基于CYP2C9和VKORC1基因多态性建立的华法林稳定剂量预测公式,能帮助指导华法林在老年房颤患者中的抗凝治疗。     

肇庆地区人群华法林相关基因CYP2C9*3和VKORC1的多态性分布研究及指导价值

目的 探讨广东省肇庆地区人群华法林相关基因细胞色素P450复合物亚基2C9（CYP2C9）和维生素K环氧还原酶复合物亚基1（VKORC1）多态性分布,并比较性别和中国西双版纳傣族、北京汉族、南方汉族间差异性的分布,为临床医生精准使用华法林进行抗凝治疗提供理论基础。方法 选取2019年5月-2022年1月于肇庆市第一人民医院进行华法林相关基因检测的患者122例,所有患者均采用数字荧光分子杂交技术对CY92C9^*3和VKORC1进行基因多态性检测,比较患者性别间和中国西双版纳傣族、北京地区汉族、南方地区汉族间的基因多态性分布情况,并对比基于药物基因组学指导下的华法林使用剂量与常规剂量使用华法林治疗后2~3 d后国际标准化比值（INR）达标率。结果 122例检测样本中,CY92C9^*3基因位点AA、AC、CC基因型所占的比例分别为95.90%、4.10%、0,C等位基因和T等位基因频率分别为97.95%和2.05%;VKORC1基因位点GG、GA、AA基因型分别为0.82%、19.67%、79.51%,A等位基因和C等位基因频率分别为10.66%和89.34%。不同性别间CY92C9^*3与VKORC1的基因型分布和等位基因分布差异均无统计学意义（P>0.05）。通过已有的数据库进行对比,肇庆地区的CY92C9^*3基因型、等位基因与1000 Genomes Project （1000 GP）西双版纳傣族、北京汉族与南方汉族对比无统计学差异（P>0.05）;但与1000 GP北京汉族对比,VKORC1的基因型和等位基因频率有统计学差异（P<0.05）;与1000GP西双版纳傣族对比,VKORC1的等位基因频率有统计学差异（P<0.05）;华法林在基因组学指导下的剂量与常规剂量治疗后INR达标率差异有统计学意义（P<0.01）。结论 肇庆地区人群存在CY92C9^*3和VKORC1基因多态性,其中VKORC1基因可能存在地域的差异,进行华法林相关基因检测可以为临床制定个体化华法林抗凝方案提供重要的参考价值。     

基因多态性对华法林个体化药量作用的临床分析

目的探讨细胞色素氧化酶P450（CYP2C9）和环氧化物还原酶复合体（VKORC1）基因型与华法林个体化剂量的关系。方法应用PCR-RFLP方法,检测临床长期口服华法林患者（362例）的VKORC1-1639及CYP2C9-1061A/C多态性,并按其基因型分组,分别比较VKORC1和CYP2C9不同基因型间的平均华法林剂量。结果病例检测出VKORC1-1639 AA基因型273例（75.4%）、AC基因型81例（22.3%）及CC基因型8例（2.3%）。CYP2C9基因检测AA型321例（88.7%）、AG基因型34例（9.5%）、GG型7例（1.8%）。两组VKORC1和CYP2C9各基因型分布差异无统计学意义（P〉0.05）。VKORC1不同基因型间患者所需华法林平均剂量GA、GG组明显高于AA组（P〈0.01）。携带CYP2C9基因型的患者（AG＋GG）组华法林平均剂量要低于AA组（P〈0.05）。结论华法林应用剂量偏低可能与VKORC G-C和CYP2C9 A-G转变有关。VKORC1 AA型占多数可能是中国汉族人群所需华法林剂量普遍较低的重要原因。     

CYP2C9和VKORC1基因多态性对新疆少数民族患者华法林初始抗凝效果的影响

目的:观察CYP2C9和VKORC1基因多态性对新疆少数民族患者华法林初始抗凝效果的影响。方法:选择行心脏瓣膜置换术并首次服用华法林的少数民族患者100例,于每日16:00时给予华法林,起始剂量2.5mg/d,3d后根据国际标准化比值(INR)调整剂量。应用基因芯片法检测其CYP2C9、VKORC1-1639AG、VKORC1+1173CT基因多态性,并记录患者使用华法林的初始剂量和INR达标时间,观察患者发生INR>3.0以及严重出血或栓塞等不良事件的发生率。结果:100例患者中,VKORC1-1639AA(VKORC1+1173TT)型患者39例,VKORC1-1639AG(VKORC1+1173CT)型患者51例,VKORC1-1639GG(VKORC1+1173CC)型患者10例;CYP2C9基因*1*1型74例,*1*2型9例,*1*3型14例,*3*3型3例。CYP2C9基因*1*1和*1*2型患者的INR首次达标时间与华法林剂量均显著多于CYP2C9基因*1*3和*3*3型患者,差异有统计学意义(P<0.05);VKORC1-1639AG和GG基因型患者的INR首次达标时间与华法林剂量均显著多于VKORC1-1639AA基因型患者(P<0.05);仅VKORC1基因变异的患者的INR首次达标时间和用药剂量显著多于两个基因均无变异和仅CYP2C9基因变异的患者,差异有统计学意义(P<0.05)。结论:CYP2C9和VKORC1基因多态性是影响华法林抗凝效果的重要因素,新疆维吾尔族和哈萨克族患者CYP2C9和VKORC1基因型变异率高,在服用华法林前进行基因检测具有重要意义。     

基于CYP2C9和VKORC1基因多态性预测老年房颤患者使用华法林的稳定剂量

目的:探讨CYP2C9和VKORC1基因多态性对房颤患者华法林稳定剂量的影响,建立适合汉族人群老年房颤患者的华法林给药模型,指导华法林个体化抗凝治疗。方法:对200例口服华法林抗凝的老年患者进行CYP2C9和VKORC1基因分型,比较不同基因型房颤患者华法林日均稳定剂量的差异。采用多元线性回归分析法依据CYP2C9和VKORC1基因型、年龄、身高、体质量、合并用药建立华法林稳定剂量计算公式。结果:INR稳定在2.0～3.0之间时,CYP2C9*1/*1基因型患者日均使用华法林剂量(3.87±0.71)mg显著高于CYP2C9*3基因型患者(1.05±0.59)mg;VKORC1-1639AA基因型患者日均使用华法林剂量(2.94±1.03)mg显著低于VKORC1-1639GA/GG基因型患者(5.76±1.12)mg。通过多元线性回归分析得出华法林稳定剂量公式,建立的回归模型中包含年龄、体质量、合并用药、CYP2C9*3和VKORC1-1639基因型,该模型能解释约56.5%个体间华法林剂量差异。结论:基于CYP2C9和VKORC1基因多态性建立的华法林稳定剂量预测公式,能帮助指导华法林在老年房颤患者中的抗凝治疗。     

VKORC1-3673G>A、CYP2C9*3、CYP4F2 rs2108622和CYP2C19*2基因多态性对中国汉族房颤患者华法林维持剂量的影响

目的 探讨VKORC1-3673G>A、CYP2C9^*3、CYP4F2 rs2108622和CYP2C19^*2位点基因多态性对中国汉族房颤患者华法林维持剂量的影响。方法 收集107例服用华法林达维持剂量的汉族房颤患者的血样和临床相关资料,应用PCR-RFLP法检测VKORC1-3673G>A、CYP2C9^*3、CYP4F2 rs2108622和CYP2C19^*2基因型,采用独立样本t检验分析基因型与华法林维持剂量的相关性。多元线性回归建立给药模型,探讨基因多态性对华法林维持剂量的影响。结果 VKORC1-3673G>A、CYP2C9^*3、CYP4F2 rs2108622基因多态性和患者年龄、体质量能解释45.2%的华法林维持剂量差异。CYP2C19^*2基因多态性对本研究人群华法林维持剂量无影响。结论 VKORC1-3673G>A、CYP2C9^*3、CYP4F2 rs2108622基因多态性显著影响中国汉族房颤患者的华法林维持剂量。     

北方地区老年患者VKORC1、CYP2C9、CYP4F2基因多态性对华法林抗凝效果的影响

目的:观察VKORC1、CYP2C9、CYP4F2基因多态性对北方地区机械瓣膜置换术后老年患者(60~75岁)华法林抗凝作用的影响。方法:研究纳入68例在北京安贞医院接受机械瓣膜置换术后华法林抗凝治疗的北方地区老年患者,同期入组68例接受瓣膜置换术后中青年患者(18~59岁),用Illumina SNP Golden Gate芯片技术检测患者VKORC1、CYP2C9、CYP4F2单核苷酸多态位点,随机抽取20%样本用Sanger法直接测序验证,统计分析各组患者华法林抗凝指标差异和老年组患者3种基因位点多态性与华法林稳定剂量的相关性。结果:136例患者VKORC1 rs9923231、CYP2C9 rs1057910、CYP4F2 rs2108622基因分布符合遗传平衡,老年组患者华法林日均稳定剂量(2.89±1.00)mg·d~(-1)显著低于中青年组(3.29±0.90)mg·d~(-1)(P<0.05)。老年患者携带VKORC1 rs9923231 CT突变型患者华法林稳定剂量(3.56±0.89)mg·d~(-1)显著高于TT纯合型患者(2.72±0.96)mg·d~(-1)(P<0.01)。老年组CYP2C9、CYP4F2各基因型组间华法林剂量无统计学差异(P>0.05)结论:老年患者服用华法林剂量明显减低,建议老年患者服用华法林时考虑检测VKORC1基因。     

CYP2C9和VKORC1基因多态性对肺栓塞患者华法林初始抗凝疗效的影响

目的评价细胞色素P450酶2C9(CYP2C9)及维生素K环氧化物还原酶复合体亚单位1(VKORC1)基因多态性对中国肺栓塞患者华法林初始抗凝疗效的影响。方法初次服用华法林抗凝的中国肺栓塞患者95例,用TaqMan MGB探针法,检测CYP2C9*2、*3位点和VKORC1-1639A>G位点基因型。记录患者的年龄、性别、体重、身高、服用华法林后每次INR值等指标,并记录患者从服用华法林开始到INR首次达标的时间、INR首次达标时华法林总剂量和日平均剂量等指标。结果 VKORC1-1639AG/GG基因型患者比VKORC1-1639AA基因型患者INR首次达标时间明显延长(P<0.001),且INR首次达标时所服用的华法林总剂量和日均剂量均高于后者(P<0.001);CYP2C9*2或*3变异的患者在初始抗凝阶段发生INR超过治疗窗(INR>3)的比例较高。患者性别、年龄、体重、CYP2C9和VKORC1基因型等因素在内的华法林初始剂量预测模型可解释54.6%左右的华法林剂量个体差异(R2=0.546,P<0.001)。结论 CYP2C9和VKORC1基因型检测对指导中国肺栓塞患者初始抗凝阶段个体化应用华法林有一定的临床意义。     

Pharmacokinetic and pharmacodynamic variation associated with VKORC1 and CYP2C9 polymorphisms in Thai patients taking warfarin

We investigated the influence of genetic polymorphisms of CYP2C9 and VKORC1 genotypes on the pharmacokinetics and pharmacodynamics of warfarin and established an equation for predicting the maintenance dose of warfarin in the Thai population using genetic and non-genetic factors. The CYP2C9*2, CYP2C9*3, VKORC1 C1173T and VKORC1 G-1639A genotypes were detected by realtime PCR using fluorogenic hybridization probes. The associations between genetic and demographic factors with respect to warfarin dosage were analyzed. CYP2C9 polymorphisms affect warfarin metabolism as shown by a significant difference in warfarin clearance, whereas VKORC1 genotypes cause a significant difference in warfarin sensitivity index (INR:Cp). The mean weekly warfarin dose was significantly different among different VKORC1 and CYP2C9 genotypes. Patients with the VKORC1 BB haplotype and CYP2C9*1/*1 required about twice the warfarin dose compared to those with the VKORC1 AA haplotype and CYP2C9*1/*1. Using stepwise multiple linear regression, clinical factors (age and weight) and genetic factors (CYP2C9 and VKORC1) could explain about 53.8% of the variance of the warfarin maintenance dose. CYP2C9 and VKORC1 genotypes played an important role in the inter-individual variation in warfarin maintenance dose in a Thai population.     

Contribution of age,body weight,and CYP2C9 and VKORC1 genotype to the anticoagulant response to warfarin: proposal for a new dosing regimen in Chinese patients

Objective The objective of this study was to assess the contribution of the VKORC1 and CYP2C9 genotypes and age, body size, and weight of the patients to the warfarin dose requirement in a Chinese population. Methods Blood samples were collected from 178 Chinese patients with stable warfarin dose requirements and an international normalized ratio (INR) of the prothrombin time within the target range (1.5–3.0). The polymorphisms for the VKORC1 (-1639GA) and CYP2C9*3 genotypes, venous INR, and plasma concentration and unbound concentration of warfarin were then analyzed. Results VKORC1 (-1639G>A) genotyping showed that 149 patients were homozygous AA, 28 were heterozygous GA, and one was homozygous for the GG genotype. CYP2C9*3 genotyping showed that 162 patients were *1/*1, and 16 patients were heterozygous *1/*3. Patients with the VKORC1(-1639 GG+GA) (3.32 ± 1.02 mg/day) and CYP2C9*1/*1 (2.06 ± 0.82 mg/day) genotypes required a significantly higher warfarin dose than those with the -1639 AA (1.76 ± 0.57 mg/day; P < 0.001) or CYP2C9*1/*3 (1.60 ± 1.29 mg/day; P < 0.001), genotype. The multiple linear regression model for warfarin dose indicated significant contributions from age (r ² = 0.084; P < 0.001), weight (r ² = 0.063; P < 0.001), VKORC1 genotype (r ² = 0.494; P < 0.001), and age, weight, and CYP2C9 and VKORC1 genotype together (r ² = 0.628; P < 0.001). Conclusion This study shows that age, weight and the VKORC1 and CYP2C9 polymorphism affect warfarin dose requirements in our sample of Chinese patients receiving long-term therapy and showing stable control of anticoagulation. It is anticipated that the use of dosing regimens modified by taking into account the contribution of age, weight, and the CYP2C9 and VKORC1 genotypes has the potential to improve the safety of warfarin therapy.     

Influence of CYP2C9 and VKORC1 polymorphisms on warfarin and acenocoumarol in a sample of Lebanese people

The authors assessed the impact of CYP2C9*2, CYP2C9*3, and/or VKORC1-1639G>A/1173C>T single-nucleotide polymorphisms on oral anticoagulants in a Lebanese population. This study recruited 231 Lebanese participants on long-term warfarin or acenocoumarol maintenance therapy with an international normalized ratio (INR) monitored at the American University of Beirut Medical Center. CYP2C9 and VKORC1 variant alleles were screened by real-time PCR. Plasma R- and S-warfarin and R- and S-acenocoumarol levels were assayed using high-performance liquid chromatography. The variant allele frequencies of CYP2C9*2, CYP2C9*3, and VKORC1 -1639G>A/1173C>T were 15.4%, 7.8%, and 52.4%, respectively. Fifty-five participants were excluded from analysis because of nontherapeutic INR values at recruitment, leaving 43 participants taking warfarin and 133 taking acenocoumarol. There was a significant decrease in the weekly maintenance dose of both drugs with CYP2C9 and VKORC1 variants when compared with wild-type patients. CYP2C9*2 had the least impact on the response to both drugs. The concentrations of R- and S-warfarin in plasma were significantly correlated with CYP2C9 genotypes. For acenocoumarol, time to reach target INR was more prolonged in patients carrying any CYP2C9 variant allele but failed to reach statistical significance because of low numbers of patients. There was no association between allelic variants and bleeding events. This is the first pharmacogenetic study of oral anticoagulants in Arabs. The authors showed that both CYP2C9 and VKORC1 polymorphisms are common in Lebanon and influence warfarin and acenocoumarol dose requirements, with the CYP2C9*2 polymorphism having less effect on acenocoumarol, the most commonly used oral anticoagulant in Lebanon.     

Influence of CYP2C9 and vitamin k oxide reductase complex (VKORC)1 polymorphisms on time to determine the warfarin maintenance dose

Polymorphisms in cytochrome P450 (CYP) 2C9 and the vitamin K oxide reductase complex subunit 1 (VKORC1) greatly affect the maintenance dose of warfarin. To prevent adverse events, immediate dose adjustment is required. The purpose of this study was to investigate the influence of these polymorphisms on the time taken to determine the warfarin maintenance dose for individual patients, and to assess the advantages of genotype-based dosing on initial anticoagulant therapy. We analyzed the genotypes of CYP2C9 and VKORC1 from 72 patients. The number of days taken to determine the maintenance dose was compared with the genotypes. The time taken to determine the maintenance dose of warfarin in group A (CYP2C9*1/*1, VKORC1 -1639AA), B (*1/*1, - 1639GA), C (*1/*3, - 1639AA), and D (*1/*3, - 1639GA) patients was 19 +/- 19, 28 +/- 28, 27 +/- 20 and 7 days, respectively. We analyzed the relationship between the initial dose of warfarin and the number of days required to determine the maintenance dose based on the VKORC1 genotypes. Patients with the VKORC1 - 1639AA genotype and who were initially treated with more than 3mg warfarin, required approximately 2 weeks for the maintenance dose to be determined. Patients with the VKORC1 - 1639GA genotype and the same initial warfarin dosage required approximately a month; however, patients initially treated with 5 mg of warfarin only required 9.5 +/- 5.3 days. We found a tendency that the time taken to determine the warfarin maintenance dose depends on the genotypes. Genotype-based dosing may improve initial anticoagulant therapy.     

Effect of CYP2C9 and VKORC1 genetic variations on warfarin dose requirements in Indian patients

BackgroundWarfarin, an oral anticoagulant is used in patients who are at increased risk of developing blood clots. The management of warfarin therapy is challenging because it shows large inter and intra individual variability in patient response due to factors like age, gender, diet, concurrent drug interactions and variations in CYP2C9 and VKORC1 genes. Studies implicate that polymorphisms in VKORC1 and CYP2C9 genes are associated with reduced doses of warfarin. The aim of our current study was to characterize the effects of VKORC1 and CYP2C9 gene variations that contribute to variability in warfarin dosing in Indian patients.MethodsGenomic DNA was extracted from 103 patients undergoing warfarin therapy. Their mean daily warfarin dose, INR and demographics were recorded and genotyping of VKORC1 and CYP2C9 gene was performed by PCR-RFLP method.ResultsIndividuals with wild type genotypes required highest mean warfarin dosage of 4.72 mg/day while VKORC1 variants required 3.6 mg/day to maintain their therapeutic INR. CYP2C9*2 genotype was not found to affect the warfarin maintenance dosages. The odds ratio for developing supra therapeutic INR in patients carrying VKORC1 variant allele when compared to wild types was 13.96 (95% CI; 4.85 – 44.65. Other factors affecting warfarin dosages were age and weight.ConclusionInclusion of pharmacogenetic data along with clinical parameters would help better predict warfarin doses in Indian patients.     

新疆维吾尔族和哈萨克族健康人群CYP2C9和VKORC1基因多态性研究

目的：了解细胞色素P450（CYP）2C9、维生素K环氧化还原酶复合体1（VKORC1）基因单核苷酸多态性在新疆维吾尔族和哈萨克族健康人群中的频率分布及与其他不同民族之间的差异,为新疆维吾尔族和哈萨克族人群实施华法林个体化用药剂量提供理论依据。方法：采用BaiO华法林敏感性基因检测试剂盒的芯片检测技术对506位新疆维吾尔族和哈萨克族健康者的CYP2C9＊2和CYP2C9＊3位点以及VKORCI（-1639A/G和1173T/C）位点基因多态性进行检测,统计其等位基因和基因型频率,并与国外多个民族的这两个基因多态性分布进行比较。结果：506份样本中共检测到CYP2C9的3种等位基因CYP2C9＊1、CYP2C9＊2和CYP2C9＊3,等位基因频率分别为89.6%、2.8%和7.6%;5种等位基因型分别为CYP2C9＊1/＊1,CYP2C9＊1/＊2,CYP2C9＊1/＊3,CYP2C9＊2/＊3和CYP2C9＊3/＊3。VKORC1-1639A/G检测出两种等位基因A和G,其频率分别为63.8%和36.2%;三种等位基因型AA（41.7%）、AG（44.3%）和GG（14%）的频率分别与1173T/C的TT、TC和CC型完全相同。结论：新疆维吾尔族和哈萨克族人群CYP2C9和VKORC1存在明显的基因多态性,其分布与中国汉族等亚洲人群以及欧美人群均存在较大差异。     

Impact of Genetic Factors (CYP2C9, VKORC1 and CYP4F2) on Warfarin Dose Requirement in the Turkish Population

Warfarin has a narrow therapeutic index and displays marked person‐to‐person variation in dose requirement. Functional polymorphisms at candidate genes can therefore offer utility as biomarkers to individualize warfarin treatment. The main objective of this study was to determine whether and to what extent variability in warfarin dose requirements was determined by polymorphisms in CYP2C9, VKORC1, CYP4F2 (rs2108622) and EPHX1 (rs2292566) in the Turkish population. Patients (n = 107) who had stable doses and international normalized ratio (INRs) at their last three consecutive visits were registered. Their demographic factors, concurrent medications, warfarin‐related bleedings or thromboembolisms, smoking, alcohol intake and weekly green vegetable consumption were recorded. From a blood sample, DNA was isolated and genotyped by real‐time PCR for polymorphisms of CYP2C9, VKORC1, CYP4F2 and EPHX1. A regression analysis was used to determine the independent effects of genetic and non‐genetic factors on warfarin dose optimization. In our study, in addition to age, genetic variants of CYP2C9, VKORC1 and CYP4F2 were found to be significant predictor variables for the maintenance dose for warfarin, explaining 39.3% of dose variability. VKORC1 and CYP2C9 genotypes remain predictor variables of the warfarin dose, and we first found that CYP4F2 (rs2108622) contributes to dose variability in the Turkish population as well. These observations may be of benefit to future translation research with a view to global personalized medicine in regions hitherto understudied such as the Turkish population so as to rationalize initial warfarin dose and reduce the burden of frequent INR measurements.