Frequencies of polymorphisms in CYP2C9 and VKORC1 genes influencing warfarin metabolism in Slovak population: implication for clinical practice.

OBJECTIVES: The study was aimed at establishing an effective molecular-genetic method for detecting polymorphisms in genes CYP2C9 and VKORC1, which affect the pharmacogenetics of warfarin, and at determining their prevalence in Slovak population. BACKGROUND: Warfarin, derivative of coumarin, belongs to the most commonly prescribed oral anticoagulants with narrow therapeutic index. An insufficient dose of warfarin can result in failure to produce the antithrombotic effect, whereas an overdose increases the risk of bleeding. It was proven that genetic variability in two genes, CYP2C9 a VKORC1, has a significant influence on the individual's response to the dosage of warfarin. METHODS: In a control group of 112 randomly selected individuals, we tested the frequency of selected single nucleotide polymorphisms including CYP2C9*2 (430C>T), CYP2C9*3 (1075A>C), VKORC1*2 (1173C>T) by allele-specific Real-Time PCR and VKORC1*2 (-1639G>A) by using PCR-RFLP. RESULTS: Due to the combination of frequent alleles CYP2C9*2, CYP2C9*3 and VKORC1*2 in Slovak population we determine that 25% of population need a standard 5-mg daily dose of warfarin, while 44%, 23%, and 8% need 4 mg, 3 mg and 2 mg of warfarin per day. CONCLUSION: Slovak population is in Hardy-Weinberg equilibrium and frequencies of SNPs were in accordance with other published results in European populations (Tab. 5. Fig. 3, Ref. 51).

Frequency of selected single nucleotide polymorphisms influencing the warfarin pharmacogenetics in Slovak population.

OBJECTIVE: Warfarin represents the most commonly prescribed oral anticoagulants, which functions as an antagonist of vitamin K, an essential factor of blood coagulation cascade. Warfarin has a narrow therapeutic index. An insufficient dose can cause failure of antithrombotic effect, and an overdose increases a risk of bleeding. It is known that variability in two genes (CYP2C9 and VKORC1) has a significant effect on individual response to warfarin dose. These polymorphisms influence more than one-third of known warfarin dose effect. Pharmacogenetics of warfarin is less affected by polymorphisms in the other genes such as CYP4F2, CYP2C19, and GGCX. MATERIAL AND METHODS: The frequency of selected single nucleotide polymorphisms including CYP2C9*2 (430C > T), CYP2C9*3 (1075A > C), VKORC1*2 (-1639G > A/1173C > T), VKORC1*3 (3730G > A), GGCX (12970C > G, 8016G > A), CYP2C19*2 (681G > A), and CYP4F2*3 (1297G > A) was tested in a control group consisting of 112 randomly selected individuals by allele-specific real-time PCR, restriction fragment length polymorphism, and bidirectional PCR allele-specific amplification. RESULTS AND DISCUSSION: The current results were statistically evaluated and compared with other populations. The presented results in Slovak population which is in Hardy-Weinberg equilibrium were compared with the prevalence in different countries. The incidence of selected polymorphisms in Slovak population correlates with Caucasians.