DO VKORC1 AND CYP2C9 MUTATIONS LEAD TO WARFARIN RESISTANCE?

The objective of this study was to determine the influence of VKORC1 and CYP2C9 polymorphisms on warfarin resistant patients. Warfarin resistance is described as the inability to prolong the prothrombin time or raise the INR up to the 2 therapeutic range when the drug is given at typically doses. Polymorphisms may play a role as some VKORC1 and CYP2C9 variant alleles are known to be associated with these circumstances. 28 patients who were taking warfarin more than 15 mg/day and had INR values below 2.1 and had thromboembolic events while using warfarin were enrolled in this study. Heterozygote mutation in the VKORC1 gene was identified in 15 of 28 patients. Seven patients had heterozygote mutation of the CYP2C9 gene, and that may correspond to the ultrarapid metabolism of warfarin. VKORC1 and CYP2C9 polymorphism contribute to the difference in dose requirement amongst the patients, but other additional possible factors may play a role in different races. We suggest that medicians may use this tests before starting warfarin therapy and shape the treatment course according to this results.

Level of mutation of the VKORC1 resistance gene to anticoagulants in house mice and norway rats in Moscow and Moscow region

The resistance of house mice (M. musuclus linnaeus, 1758) and norway rats (R. norvegicus berkenhout, 1769) to anticoagulants of the 1st and 2nd generation in the VKORC1 gene in Moscow and the Moscow region was studied. House mice had two previously unknown mutations in exon 1: Lys175Arg и Ser94Trp. We assume that these mutations can increase the resistance of rodents to second-generation anticoagulants. the percentage of individuals with mutations in exon 1 in Moscow is 87.5 %, in Noginsk and Podolsk – 100 %. Of the 18 norway rats studied in Moscow, only three individuals in a heterozygous state were found to have one of the mutations (Tyr139Ser), usually associated with genetic resistance of rodents to the first generation anticoagulant warfarin. the percentage of resistant individuals in Moscow was 15.7 %. the rats in which the resistance mutation was found were captured in three districts of moscow: southwestern, northern and eastern.

Mus musculus populations in Western Australia lack VKORC1 mutations conferring resistance to first generation anticoagulant rodenticides: Implications for conservation and biosecurity

BackgroundHumans routinely attempt to manage pest rodent populations with anticoagulant rodenticides (ARs). We require information on resistance to ARs within rodent populations to have effective eradication programs that minimise exposure in non-target species. Mutations to the VKORC1 gene have been shown to confer resistance in rodents with high proportions of resistance in mice found in all European populations tested. We screened mutations in Mus musculus within Western Australia, by sampling populations from the capital city (Perth) and a remote island (Browse Island). These are the first Australian mouse populations screened for resistance using this method. Additionally, the mitochondrial D-loop of house mice was sequenced to explore population genetic structure, identify the origin of Western Australian mice, and to elucidate whether resistance was linked to certain haplotypes.ResultsNo resistance-related VKORC1 mutations were detected in either house mouse population. A genetic introgression in the intronic sequence of the VKORC1 gene of Browse Island house mouse was detected which is thought to have originated through hybridisation with the Algerian mouse (Mus spretus). Analysis of the mitochondrial D-loop reported two haplotypes in the house mouse population of Perth, and two haplotypes in the population of Browse Island.ConclusionsBoth house mouse populations exhibited no genetic resistance to ARs, in spite of free use of ARs in Western Australia. Therefore weaker anticoagulant rodenticides can be employed in pest control and eradication attempts, which will result in reduced negative impacts on non-target species. Biosecurity measures must be in place to avoid introduction of resistant house mice, and new house mouse subspecies to Western Australia.

The effects of CYP2C9 and VKORC1 gene polymorphisms on warfarin maintenance dose in Turkish cardiac patients

Aim: Our aim was to examine the effect of CYP2C9 and VKORC1 polymorphisms on warfarin dose requirements in Turkish patients. Materials & methods: 24 warfarin prescribed patients were included and analyzed for eight VKORC1 and 6 CYP2C9 polymorphisms in the study. Results: Patients with CYP2C9 *1/*1 and VKORC1 -1639 GG and GA genotypes required higher warfarin doses in comparison to wild type VKORC1 genotype. Patients with CYP2C9 *1/*3 and VKORC1 -1639 GG genotypes simultaneously, required the lowest dose of warfarin (4.64 mg/day). Patients with CYP2C9 *1/*1 and VKORC1 9041 AA genotype were found to require higher warfarin doses. Conclusion: Our results provide additional evidence to support the hypothesis that CYP2C9 *2, *3, VKORC1 9041 G > A polymorphisms explain considerable proportion of inter-individual variability in warfarin dose requirement.

Population frequencies of vkorc1 c1173t polymorphism, which determining the organism sensitivity to warfarin, in forest nenets and nganasans of northern siberia

Полиморфизм C1173T гена VKORC1 является одним из ключевых факторов, определяющих как этнические, так и индивидуальные различия в чувствительности к антикоагулянту варфарину и его поддерживающей дозе у пациентов при лечении тромбозозависимых заболеваний. В связи с этим, на популяционном уровне проведено исследование полиморфизма VKORC1 C1173T среди коренных представителей лесных ненцев Ямало-Ненецкого автономного округа и нганасан полуострова Таймыр Красноярского края. Генотипирование однонуклеотидных замен в гене VKORC1 проводилось в режиме реального времени с использованием конкурирующих TaqMan-зондов. Выявлено, что вариант VKORC1 1173T встречается с высокой частотой в изученных популяциях: 67% у лесных ненцев и 94% у нганасан. Этот показатель существенно и статистически значимо выше, чем у европейцев, и имеет схожий характер распространения с таковым у азиатов Китая и Японии. Результаты нашего исследования расширяют знания о полиморфизме гена VKORC1 в человеческих популяциях, а также способствуют развитию персонализированной медицины по отношению к коренным жителям Сибири, так как генетический статус человека, имеющего вариант 1173T, может учитываться в целях достижения максимально безопасной и эффективной терапии варфарином при тромбозозависимых заболеваниях. Polymorphism C1173T of the VKORC1 gene is one of the key factors determining both ethnic and individual differences in the sensitivity to the anticoagulant warfarin and its maintenance dose in patients in the treatment of thrombosis-dependent diseases. In this regard, at the population level the VKORC1 C1173T polymorphism was studied in indigenous populations of the Forest Nenets (the Yamal-Nenets Autonomous Okrug) and Nganasans (the Taimyr Peninsula of the Krasnoyarsk region). Genotyping of C1173T single nucleotide substitution in the VKORC1 gene was carried out in real time using competing TaqMan probes. It was revealed that the variant VKORC1 1173T occurs with a high frequency in the studied populations: 67% in Forest Nenets and 94% in Nganasans. This indicator is significantly higher than that of Europeans, and has a similar distribution pattern with that of Asians. The results of our study expand knowledge about VKORC1 gene polymorphism in human populations, and also promote the development of personalized medicine in relation to indigenous people of Siberia, since the genetic status of a person with variant 1173T can be taken into account at an individual level in order to achieve the most safe and effective warfarin therapy of thrombosis-dependent diseases.