Effects of CYP2C9 and VKORC1 genetic polymorphisms in Chinese Han population on maintenance dosage of warfarin / 中华检验医学杂志

Objective@#To analyze CYP2C9 and VKORC1 gene polymorphisms in Chinese Han population and their correlation with the maintenance dosage of warfarin.@*Methods@#From October 2017 to April 2018, 458 Chinese Han patients (213 males and 245 females, aged from 26 to 94 years old) who underwent coagulation analysis in Peking University People′s Hospital were included in this retrospective study. PCR-Fluorescent probe method was applied to detect CYP2C9*3 and VKORC1-1639A>G gene polymorphisms in 458 patients, and among them, 130 patients who took warfarin for anticoagulant therapy and reached the international standard ratio of prothrombin time (INR) within the range of 2.0-3.0 were recorded. The basic information, dosage of warfarin and INR were also recorded. The statistical analysis data were compared with the reference table of recommended dosage of warfarin for different genotypes of patients recommended by FDA and the formula of predicted dosage of warfarin was simply verified by SPSS.@*Results@#Among the 458 patients who took anticoagulant therapy, the genotype frequencies of CYP2C9*1/*1(AA), CYP2C9*1/*3(AC) and CYP2C9*3/*3(CC) were 90.8%, 8.5%, and 0.7%; the genotype frequencies of VKORC1-1639GG and VKORC1-1639AG were 0.9% and 14.2%; the genotype frequencies of VKORC1-1639AA was 84.9%. After INR was reached, the results showed that the variant CYP2C9*1/*3 and CYP2C9*3/*3 required lower daily maintain dosage [(2.92±1.29) mg] than wild-type CYP2C9*1/*1 patients did [(3.91±1.63) mg], with statistically significant difference (P=0.018). And variant VKORC1-AA required lower daily maintain dosage [(3.68±1.64) mg] than variant VKORC1-AG patients did [(4.54±1.29) mg], with statistically significant difference (P=0.001). The application dosage of warfarin in patients with different VKORC1+CYP2C9 genotypes was consistent with the recommended dosage of the FDA reference table. The prediction accuracy of miao 2007 formula was lower than that of IWPC formula, and 94.1% of patients′ dosages of warfarin were underestimated.@*Conclusion@#Patients with CYP2C9*3 or VKORC1-AA genotype required lower warfarin dosage. The CYP2C9 and VKORC1 gene polymorphisms had a certain correlation with maintenance dosage of warfarin.

Nurse empowerment through Pharmacogenetics / Empoderamento do enfermeiro por meio da Farmacogenética / Empoderamiento del enfermero a través de la farmacogenética

Objective: to verify the existence of elements that justify the use of pharmacogenetics by the Brazilian nurse. Method: this is a quantitative, cross-sectional, observational, descriptive study, whose final sample was 67 individuals. The participants were healthy at the time of the study and reported a history of previous use and the occurrence of adverse effects by drugs commonly used and metabolized by CYP2C9. We collected 4 mL of venous blood for subsequent DNA extraction by salting out method and genotyping of the CYP2C9*2 and CYP2C9*3 polymorphisms, using Polymerase Chain Reaction in real time using Taqman assays. Results: the use of drugs metabolized by CYP2C9 was frequent (more than 75% of the individuals have already used between 2 or 4 of these drugs). Regarding adverse events, there were 19 perceived symptomatic occurrences associated with drugs metabolized by CYP2C9. The allele frequency of the polymorphism * 2 and * 3 in the population studied was 11.1% and 7.5%, respectively, and there was a coincidence between the presence of alleles of low enzyme activity and the occurrence of adverse effects. Conclusion: there are elements that justify the adoption of pharmacogenetics in the nursing care to reduce the occurrence of adverse reactions to drugs metabolized by CYP2C9.

Objetivo: verificar a existência de elementos que justifiquem o uso da farmacogenética pelo enfermeiro brasileiro. Método: trata-se de um estudo quantitativo, do tipo transversal, observacional descritivo, cuja amostra final foi de 67 indivíduos. Os participantes estavam saudáveis no momento do estudo e reportaram histórico de uso prévio e ocorrência de efeitos adversos por fármacos comumente utilizados e metabolizados pela CYP2C9. Coletamos 4 mL de sangue venoso para posterior extração de DNA por método salting out e genotipagem dos polimorfismos CYP2C9*2 e CYP2C9*3 através de Polymerase Chain Reaction em tempo real, utilizando ensaios Taqman. Resultados: o uso de fármacos metabolizados pela CYP2C9 foi frequente (mais de 75% dos sujeitos já utilizaram entre 2 ou 4 desses fármacos). A respeito dos eventos adversos, houve 19 ocorrências sintomáticas percebidas, associadas a fármacos metabolizados pela CYP2C9. A frequência alélica do polimorfismo *2 e *3 na população estudada foi de 11,1% e 7,5%, respectivamente, com coincidência entre a presença dos alelos de baixa atividade enzimática e ocorrência de efeitos adversos. Conclusão: existem elementos que justificam a adoção da farmacogenética no cuidado do enfermeiro com objetivo de redução da ocorrência de reações adversas a fármacos metabolizados pela CYP2C9.

Objetivo: verificar la existencia de elementos que justifiquen el uso de la farmacogenética por parte del enfermero brasileño. Método: se trata de un estudio cuantitativo, transversal, observacional, descriptivo, cuya muestra final fue de 67 individuos. Los participantes estaban sanos en el momento del estudio e informaron un historial de uso previo y la aparición de efectos adversos por fármacos comúnmente utilizados y metabolizados por el CYP2C9. Recolectamos 4 ml de sangre venosa para la posterior extracción de ADN mediante el método de salazón y genotipificación de los polimorfismos CYP2C9 * 2 y CYP2C9 * 3 a través de la reacción en cadena de la polimerasa en tiempo real utilizando ensayos Taqman. Resultados: el uso de drogas metabolizadas por el CYP2C9 fue frecuente (más del 75% de las personas ya han usado entre 2 o 4 de estas drogas). Con respecto a los eventos adversos, hubo 19 casos sintomáticos percibidos asociados con medicamentos metabolizados por el CYP2C9. La frecuencia alélica del polimorfismo * 2 y * 3 en la población estudiada fue de 11.1% y 7.5%, respectivamente, y hubo una coincidencia entre la presencia de alelos de baja actividad enzimática y la aparición de efectos adversos. Conclusión: existen elementos que justifican la adopción de la farmacogenética en el cuidado del enfermero para reducir la aparición de reacciones adversas a los medicamentos metabolizados por el CYP2C9.

Efecto de las variantes de CYP2C9 sobre la dosis de losartán en hipertensos chilenos / Association between cytochrome p4502c9 polymorphisms and losartan dosing in hypertensive patients

Background Losartan is widely used in many clinicals settings. Its dosage is related to the genetic characteristics of CYP2C9 enzymatic activity, which metabolizes losartan to its active form E-3174, responsible for the antihypertensive effect. Aims To identify the frequency of allelic variants CYP2C9*2 and CYP2C9*3 in hypertensive patients and to compare genotypes with a healthy Chilean population. To relate polymorphisms with the losartan dosing to obtain an optimal blood pressure. Material and Methods We studied 30 patients with controlled essential hypertension using losartan with normal liver function, and 202 healthy people. Peripheral blood DNA genotyping was performed by polymerase chain reaction to identify the polymorphisms. Allelic and genotypic frequencies were compared. Results In hypertensive patients, allelic frequencies were 0.85 (CYP2C9*1), 0.05 (CYP2C9*2) and 0.1 (CYP2C9*3). Genotypic frequencies were 73.3% (CYP2C9*1/*1), 6.7% (CYP2C9*1/*2), 16.7% (CYP2C9*1/*3) and 3.3% (CYP2C9*2/3); observing a significantly higher frequency of the allele CYP2C9*3 (p=0.041) and CYP2C9*1/*3 genotype (p=0.04). A non-significant tendency to need a larger dose of losartan was observed with the CYP2C9 * 3 allele, with an odds ratio (OR) of 1.46 (95% confidence intervals (CI) 0.01-18.64). The same tendency was observed with the need to use losartan twice a day, obtaining an OR of 5.88 (CI 0.54 -62.14). Conclusions There could be a relationship between the presence of CYP2C9 polymorphisms and the pathogenesis of hypertension. The presence of CYP2C9*3 is associated with the need for higher doses of losartan, possibly due to a decrease in the conversion of losartan to E-3174.

Estudio de las variantes alélicas CYP2C9*2 y CYP2C9*3 en muestras de población mestiza peruana / Study of the allelic variants CYP2C9*2 and CYP2C9*3 in samples of the Peruvian mestizo population

Resumen Introducción. El citocromo CYP2C9 metaboliza, aproximadamente, el 15 % de los fármacos prescritos. Su gen presenta alelos cuyas frecuencias difieren entre grupos étnicos y poblaciones. Los alelos CYP2C9*2 y CYP2C9*3 dan cuenta de una enzima con actividad disminuida cuya frecuencia no ha sido determinada en la población mestiza peruana. Objetivo. Caracterizar la frecuencia de las variantes *2 (rs1799853) y *3 (rs1057910) del gen CYP2C9 en muestras de población mestiza peruana provenientes de Lima, Tacna y Junín. Materiales y métodos. Se hizo un estudio descriptivo, observacional y prospectivo, con muestreo no probabilístico, por conveniencia e incidental. Se incluyeron 218 sujetos según los criterios de inclusión y exclusión; todos los participantes otorgaron su consentimiento informado. El ADN genómico se obtuvo mediante hisopado de mucosa oral, y la detección de los genotipos para los alelos CYP2C9*2 y CYP2C9*3 se hizo mediante reacción en cadena de la polimerasa (PCR) en tiempo real, utilizando sondas TaqMan™. Resultados. Las variantes de CYP2C9*2 y CYP2C9*3 están presentes en la población mestiza peruana con frecuencias de 0,046 y 0,062, respectivamente. El análisis de las frecuencias genotípicas observadas permitió predecir que la frecuencia de fenotipos metabolismo intermedio sería del 15,13 % (CYP2C9*1/*2: 5,96 %; CYP2C9*1/*3: 9,17 %), y la de fenotipos de metabolismo lento, del 3,22 % (CYP2C9*2/*2: 1,38 %; CYP2C9*3/*3: 1,38 %; CYP2C9*2/*3: 0,46 %). Conclusiones. Se lograron determinar las frecuencias genotípicas y alélicas para las variantes *2 y *3 del gen CYP2C9 en una muestra no probabilística de población mestiza peruana. Las frecuencias obtenidas (0,046 y 0,062, respectivamente) están entre las esperadas para una población mestiza sudamericana con ascendencia amerindia, europea, africana y asiática.

Abstract Introduction: CYP2C9 metabolizes approximately 15% of the prescribed drugs. Its gene has alleles whose frequencies differ between ethnic groups and populations. The alleles CYP2C9*2 and CYP2C9*3 account for an enzyme with decreased activity and their frequencies have not been determined in the Peruvian mestizo population. Objective: To characterize the frequencies of the allelic variants *2 (rs1799853) and *3 (rs1057910) of CYP2C9 gen in the Peruvian mestizo population from Lima, Tacna y Junín. Materials and methods: We conducted an observational, prospective cross-sectional study with non-probabilistic, by convenience, and incidental sampling. We included 218 subjects according to the inclusion and exclusion criteria, all of whom had signed the informed consent. We obtained the genomic DNA from oral mucosa swab. For the detection of the CYP2C9*2 and CYP2C9*3 genotypes, we used real-time-polymerase chain reaction with TaqMan® probes. Results: The genotyping revealed that CYP2C9*2 and CYP2C9*3 variants have low frequencies (0.046 and 0.062, respectively). The frequency of intermediate metabolizers was 15.13% (CYP2C9*1/*2: 5.96%; CYP2C9*1/*3: 9.17%) and that of slow metabolizers was 3.22% (CYP2C9*2/*2: 1.38%; CYP2C9*3/*3: 1.38%; CYP2C9*2/*3: 0.46%). Conclusions: It was possible to determine the genotypic and allelic frequencies for the variants *2 and *3 of the CYP2C9 gene in a non-probabilistic sample of the Peruvian mestizo population. The frequencies obtained (0.046 and 0.062, respectively) corresponded to those expected for a South American mestizo population with Amerindian, European, African and Asian ancestry.

Research progress in CYP2C9 and VKORC1 gene polymorphism and individualized warfarin therapeutic regimen / 解放军医学杂志

Warfarin is still the most clinically used oral anti-coagulant despite of its narrow therapeutic index and high risk of hemorrhage. The mean daily dose of warfarin varies widely from patient to patient, and to achieve the same therapeutic effect, the daily dose of warfarin could be varied over 20-fold. The variability in warfarin dosage depends on several factors, including gene polymorphisms, index of body mass, age and other drugs, and these factors compelled the clinicians to individualize warfarin dosage in order to optimize the therapeutic regimen. A number of genes are involved in metabolism of warfarin, such as cytochrome P450 2C9 (CYP2C9), vitamin K epoxide reductase complex subunit 1 (VKORC1), cytochrome P450 4F2 (CYP4F2), gamma-glutamylcarboxylase (GGCX), etc. Of them CYP2C9 and VKORC1 are the emphasis of current researches. The association between the polymorphism of CYP2C9 and VKORC1 and individualized warfarin therapeutic regimen are mainly discussed in this paper.

A Case Report of a Patient Carrying CYP2C9*3/4 Genotype with Extremely Low Warfarin Dose Requirement

We report a case of intolerance to warfarin dosing due to impaired drug metabolism in a patient with CYP2C9*3/*4. A 73-yr-old woman with atrial fibrilation was taking warfarin. She attained a high prothrombin time international normalized ratio (INR) at the standard doses during the induction of anticoagulation and extremely low dose of warfarin (6.5 mg/week) was finally chosen to reach the target INR. Genotyping for CYP2C9 revealed that this patient had a genotype CYP2C9*3/*4. This is the first Korean compound heterozygote for CYP2C9*3 and *4. This case suggests the clinical usefulness of pharmacogenetic testing for individualized dosage adjustments of warfarin.

A Case of Intolerance to Warfarin Dosing in an Intermediate Metabolizer of CYP2C9

We report a case of intolerance to warfarin dosing due to impaired drug metabolism in a patient heterozygous for the CYP2C9*3 allele. A 30-year-old woman with an artificial cardiac pacemaker was taking warfarin to prevent thromboembolism. This patient had an extremely elevated international normalized ratio (INR) of prothrombin time (PT) following standard doses of warfarin and experienced difficulties during the induction of anticoagulation. Genotyping for CYP2C9 revealed that this patient was an intermediate metabolizer with genotype CYP2C9*1/*3. This case suggests the clinical usefulness of pharmacogenetic testing for individualized dosage adjustments of warfarin.