Study Of VKORC1&CYP2C9Gene Polymorphism And Their Significance On Warfarin Anticoagulation Intensity

BackgroudWarfarin is a coumarin anticoagulants. It is wildly being used for anticoagulanttherapy for prosthetic valve replacement, thromboembolic disease and atrial fibrillation.However, management is complicated by a narrow therapeutic index and wideinter-individual dosage variability, with potentially serious consequences at both sub-andsupra-therapeutic dose. Therefore, how to solve this problem, became the top priority ofthe majority of cardiac surgeons. Recently, with the development of warfarinpharmacogenomics reaserch, studies found genetic factors that influence thepharmacokinetics and pharmacodynamics of warfarin metabolism also affect thesteady-state warfarin dosage.In pharmacokinetics aspect, warfarin mixed by R-and S-enatiomer, it metabolismed inliver. CYP2C9catalysis S-enatiomer to6-and7-carboxylation warfarin, R-enatiomercatalysised by CYP1A1, CYP1A2and CYP3A4. In steady state, S-warfarin can educe60~70%anticoagulation, and metabolismed by CYP2C9. In pharmacodynamics aspect,VKOR turned Vit K to KH2, warfarin inhibit VKORC1, and interfere the way which Vit Kturned to KH2, accordingly blockage blood coagulation factor Ⅱ、Ⅶ、Ⅸ、Ⅹ activation thatachieved anticoagulation. So, study the relationship between gene polymorphism andwarfarin dosage have clinical significance.In some related reaserch. CYP2C9gene has wild-type (AA), mutant type (AC) andmutation of pure type (CC), VKORC1(-1639A/G) gene have three different types,wild-type (GG), mutation heterozygous (GA) and mutation of pure type (AA),VKORC1(-1173C/T) gene have three different types, wild-type (TT), mutationheterozygous (CT) and mutation of pure type (CC). Native studies shows that for theCYP2C9and VKORC1gene variants can be guide of the warfarin medication start andsafe dose. However, lately reaserch showed VKORC1(-1173C/T) gene polymorphismclosely related to warfarin dose, may be another significance influencing factors ofwarfarin dosage.Objective1. Overview CYP2C9gene polymorphisms and warfarin dosage relationship betweenindividual differences. 2. Overview VKORC1gene polymorphisms and warfarin dosage relationshipbetween individual differences.3. Comprehensive patient gene polymorphism indicators, the plasma concentration,and the patient’s clinical data, rationalization, to provide new ideas and methods ofindividualized warfarin use.Materials and MethodsCollect146patient who under prosthetic valve replacement in Shanghai ChangzhengHospital between June2012to December2012. All the patients signed the informedconsent, and their INR is2.0-3.0.1. Pyrosequencing method, by extraction in patients with peripheral venous bloodtesting genotyping and gene mutation.2. By UPLC/MS-MS (ultra performance liquid chromatography-tandem massspectrometry) Metabolomics Method for determination of plasma levels of warfarincontent of this experiment is detected from the plasma of patients with oral warfarin indifferent periods after warfarinplasma concentration changes. The warfarin standardsadded to blank plasma to confirm the warfarin plasma concentration changes.3. Collect patients detailed information, including age, gender, height, body surfacearea, smoking history, history of drinking, clinical function parameters such as thrombinoriginal time (PT), INR, activated partial thromboplastin time (APTT).4. By the gene polymorphism indicators, the plasma concentration, and the patient’sclinical data, research analysis combined action of warfarin individual dose difference,suggesting that the appropriate starting dose and stable doses of different patients,to playindividual, rationalization guiding role of medication.Results1. Test result shows that in different genome group, its gender, age, BSA, BMI,smoking, drinking, heart disease, the number of valve replacement, diabetes coincidenceHardy-Weinberg balance.2. In group CYP2C9gene, CYP2C9AA have137patients(93.8%), CYP2C9AC have9patients(6.2%), have no CC gene type; In group VKORC1-1639A/G, AA type have124patients(85.1%), GA type have22patients(14.9%), have no GG gene type; In groupVKORC1-1173C/T, TT type have118patients(81.2%), CT type have28patients(18.8%), have no CC type. Its test result coincidence Hardy-Weinberg balance (P>0.05);3. In all146patients, male is64(43.8%), their average warfarin dose is3.22±0.69mg/d, female is82(56.2%), their average dose is2.13±1.11mg/d; its variance havestatistical significance (P<0.05); subgroup patients by age, we find patients whose ageabove70(include70), the average dose is2.11±0.32mg/d, age between60to69, theaverage dose is2.14±0.60mg/d, their dose lower than other patients, its variance havestatistical significance (P<0.05);4. In all146patients whose anticoagulation sustain in INR (2.0~3.0). CYP2C9AAtype patients warfarin dose in average2.26±0.82mg/d, CYP2C9AC type patientswarfarin dose in average1.80±1.29mg/d, its variance have statistical significance(P<0.05);VKORC1-1639A/G AA type patients warfarin dose in average1.76±0.57mg/d,VKORC1-1639A/G GA type patients warfarin dose in average3.32±1.02mg/d, itsvariance have statistical significance (P<0.01); VKORC1-1173C/T TT type patientswarfarin dose in average1.81±0.63mg/d, VKORC1-1173C/T CT type patients warfarindose in average3.33±1.04mg/d, its variance have statistical significance (P<0.01).5.146cases under anticoagulant therapy after prosthetic valve replacement.VKORC1-1639A/G AA type, average warfarin dose1.76±0.57mg/d, the mean plasmawarfarin concentration596.1±249.6ng/ml, followed by the type of VKORC1-1639A/GGA type, average warfarin dose3.32±1.02mg/d, mean plasma warfarin concentration951.4±411.4ng/ml, its variance have statistical significance (P<0.01); genotype ofVKORC1-1173C/T TT type, average warfarin dose1.81±0.63mg/d, the mean plasmawarfarin concentration605.8±269.1ng/ml, followed by the type of VKORC1-1173C/T CTtype, average warfarin dose3.33±1.04mg/d, the mean plasma warfarin concentration963.0±378.4ng/ml, its variance have statistical significance (P<0.01).Conclusions1. With anticoagulant therapy after prosthetic valve replacement, patients whose ageabove70(include70) and age between60to69, the daily dose is lower than other patients;2. CYP2C9AA type patients warfarin daily dose is higher than CYP2C9AC type.3. VKORC1-1639A/G AA type patients warfarin daily dose is lower thanVKORC1-1639A/G GA type; VKORC1-1173C/T TT type patients warfarin dose is lowerthan VKORC1-1173C/T CT type.4. VKORC1-1639A/G GA type patients plasma warfarin concentration is higher than VKORC1-1639A/G AA type; VKORC1-1173C/T CT type patients plasma warfarinconcentration is higher than VKORC1-1173C/T TT type.Therefore, we suggested that, in order to gain the optimal treat effect and undertakinglower risk, it is necessary to detect CYP2C9, VKORC1-1639G/A and VKORC1-1173C/Tgene polymorphism as an instruction of warfarin daily dose.