DIPLOMA THESIS TITLE CYP2C9 and VKORC1 gene polymorphisms in the individualization of Martefarin therapy OBJECTIVES The objective of this study is to present the theoretical assumptions and gene polymorphisms of CYP2C9 and VKORC1 genes in the individualization of warfarin treatment and to determine the polymorphisms of these genes in given venous blood samples. MATERIAL AND METHODS Genomic DNA was isolated from whole blood biological samples collected from healthy volunteers. It was then quantified using a Qubit® 4.0 fluorometer in order to determine whether the optimal amount of DNA for genotyping had been isolated by the previous procedure. Genotyping of CYP2C9*2 and CYP2C9*3 as well as VKORC1 1173C>T allelic variants was performed using a real-time polymerase chain reaction method on Applied Biosystems ™ 7500 Real-Time PCR System at assigned working conditions. DNA samples and negative control were previously prepared using TaqMan® Drug Metabolism Genotyping Assays whose key components, the TaqMan® MGB probes, allow allelic variants to be determined in the samples based on the emitted fluorescence signal. RESULTS The genotype of test sample No. 1 was successfully determined and it corresponds to the wild type homozygote for each of the gene polymorphisms examined. It was not possible to accurately determine the genotype of the other samples due to a clear lack of fluorescence intensity increase of the reporter dyes in the corresponding multicomponent plots. CONCLUSION As recommended by the US Food and Drug Administration (FDA), the starting dose and maintenance dose of warfarin for a subject whose genotype matches sample number 1 is 5-7mg. The genotype of other samples could not be determined with certainty, probably due to the DNA molecule degradation caused by the long-term storage of the samples for analysis. Further prospective clinical trials need to be conducted in order to determine the efficacy and cost-effectiveness of genotyping before initiating warfarin therapy.