Association evaluations of oral anticoagulants with dementia risk based on genomic and real-world data.

BACKGROUND: Several observational studies have suggested that oral anticoagulants (OACs) might reduce the risk of dementia in the elderly, but the evidence is inconclusive. And the consistency of this relationship across different OAC classes and dementia subtypes is still uncertain. METHODS: To comprehensively evaluate this association, we applied Mendelian randomization (MR) combined with pharmacovigilance analysis. MR was used to assess the associations between genetic proxies for three target genes of OACs (VKORC1, F2, and F10) and dementia, including Alzheimer's disease (AD) and vascular dementia (VaD). This genetic analysis was supplemented with real-world pharmacovigilance data, employing disproportionality analysis for more reliable causal inference. RESULTS: Increased expression of the VKORC1 gene was strongly associated with increased risk of dementia, especially for AD (OR = 1.28, 95% CI = 1.14-1.43; p value < 0.001). Based on pharmacovigilance data, vitamin K antagonists (VKAs, inhibitors targeting VKORC1) exhibited a protective effect against dementia risk (ROR = 0.43, 95% CI = 0.28-0.67). Additional sensitivity analyses, including different MR models and cohorts, supported these results. Conversely, no strong causal associations of genetically proxied F2 and F10 target genes with dementia and its subtypes were found. CONCLUSIONS: This study reveals that the inhibition of genetically proxied VKORC1 expression or VKAs exposure is associated with a reduced risk of Alzheimer's dementia. However, there is little evidence to support similar associations with direct oral anticoagulants (F2 inhibitors and F10 inhibitors). Further research is warranted to clinically validate our findings.

Development of an electrochemical DNA-based biosensor for the detection of the cardiovascular pharmacogenetic-altering SNP CYP2C9*3.

Cardiovascular diseases are among the major causes of mortality and morbidity. Warfarin is often prescribed for these disorders, an anticoagulant with inter and intra-dosage variability dose required to achieve the target international normalized ratio. Warfarin presents a narrow therapeutic index, and due to its variability, it can often be associated with the risk of hemorrhage, or in other patients, thromboembolism. Single-nucleotide polymorphisms are included in the causes that contribute to this variability. The Cytochrome P450 (CYP) 2C9*3 genetic polymorphism modifies its enzymatic activity, and hence warfarin's plasmatic concentration. Thus, the need for a selective, rapid, low-cost, and real-time detection device is crucial before prescribing warfarin. In this work, a disposable electrochemical DNA-based biosensor capable of detecting CYP2C9*3 polymorphism was developed. By analyzing genomic databases, two specific 78 base pairs DNA probes; one with the wild-type adenine (Target-A) and another with the cytosine (Target-C) single-nucleotide genetic variation were designed. The biosensor implied the immobilization on screen-printed gold electrodes of a self-assembled monolayer composed by mercaptohexanol and a linear CYP2C9*3 DNA-capture probe. To improve the selectivity and avoid secondary structures a sandwich format of the CYP2C9*3 allele was designed using complementary fluorescein isothiocyanate-labeled signaling DNA probe and enzymatic amplification of the electrochemical signal. Chronoamperometric measurements were performed at a range of 0.015-1.00 nM for both DNA targets achieving limit of detection of 42 p.m. The developed DNA-based biosensor was able to discriminate between the two synthetic target DNA targets, as well as the targeted denatured genomic DNA, extracted from volunteers genotyped as non-variant homozygous (A/A) and heterozygous (A/C) of the CYP2C9*3 polymorphism.

GGCX mutations show different responses to vitamin K thereby determining the severity of the hemorrhagic phenotype in VKCFD1 patients.

BACKGROUND: Vitamin K dependent coagulation factor deficiency type 1 (VKCFD1) is a rare hereditary bleeding disorder caused by mutations in γ-glutamyl carboxylase (GGCX). VKCFD1 patients are treated life-long with high doses of vitamin K in order to correct the bleeding phenotype. However, normalization of clotting factor activities cannot be achieved for all VKCFD1 patients. OBJECTIVE: The current study aims to investigate the responsiveness to vitamin K for all reported GGCX mutations with respect to clotting factors in order to optimize treatment. METHODS: This study developed an assay using genetically engineered GGCX-/- cells, in which GGCX mutations were analyzed with respect to their ability to γ-carboxylate vitamin K dependent pro-coagulatory and anti-coagulatory clotting factors by ELISA. Additionally, factor VII activity was measured in order to proof protein functionality. For specific GGCX mutations immunofluorescent staining was performed to assess the intracellular localization of clotting factors with respect to GGCX wild-type and mutations. RESULTS: All GGCX mutations were categorized into responder and low responder mutations, thereby determining the efficiency of vitamin K supplementation. Most VKCFD1 patients have at least one vitamin K responsive GGCX allele that is able to γ-carboxylate clotting factors. In few patients, the hemorrhagic phenotype cannot be reversed by vitamin K administration because GGCX mutations on both alleles affect either structural or catalytically important sites thereby resulting in residual ability to γ-carboxylate clotting factors. CONCLUSION: With these new functional data we can predict the hemorrhagic outcome of each VKCFD1 genotype, thus recommending treatments with either vitamin K or prothrombin complex concentrate.

New Insights on Vitamin K Metabolism in Senegalese sole (Solea senegalensis) Based on Ontogenetic and Tissue-Specific Vitamin K Epoxide Reductase Molecular Data.

Vitamin K (VK) is a key nutrient for several biological processes (e.g., blood clotting and bone metabolism). To fulfill VK nutritional requirements, VK action as an activator of pregnane X receptor (Pxr) signaling pathway, and as a co-factor of γ-glutamyl carboxylase enzyme, should be considered. In this regard, VK recycling through vitamin K epoxide reductases (Vkors) is essential and should be better understood. Here, the expression patterns of vitamin K epoxide reductase complex subunit 1 (vkorc1) and vkorc1 like 1 (vkorc1l1) were determined during the larval ontogeny of Senegalese sole (Solea senegalensis), and in early juveniles cultured under different physiological conditions. Full-length transcripts for ssvkorc1 and ssvkorc1l1 were determined and peptide sequences were found to be evolutionarily conserved. During larval development, expression of ssvkorc1 showed a slight increase during absence or low feed intake. Expression of ssvkorc1l1 continuously decreased until 24 h post-fertilization, and remained constant afterwards. Both ssvkors were ubiquitously expressed in adult tissues, and highest expression was found in liver for ssvkorc1, and ovary and brain for ssvkorc1l1. Expression of ssvkorc1 and ssvkorc1l1 was differentially regulated under physiological conditions related to fasting and re-feeding, but also under VK dietary supplementation and induced deficiency. The present work provides new and basic molecular clues evidencing how VK metabolism in marine fish is sensitive to nutritional and environmental conditions.

A cell-based high-throughput screen identifies drugs that cause bleeding disorders by off-targeting the vitamin K cycle.

Drug-induced bleeding disorders contribute to substantial morbidity and mortality. Antithrombotic agents that cause unintended bleeding of obvious cause are relatively easy to control. However, the mechanisms of most drug-induced bleeding disorders are poorly understood, which makes intervention more difficult. As most bleeding disorders are associated with the dysfunction of coagulation factors, we adapted our recently established cell-based assay to identify drugs that affect the biosynthesis of active vitamin K-dependent (VKD) coagulation factors with possible adverse off-target results. The National Institutes of Health (NIH) Clinical Collection (NCC) library containing 727 drugs was screened, and 9 drugs were identified, including the most commonly prescribed anticoagulant warfarin. Bleeding complications associated with most of these drugs have been clinically reported, but the pathogenic mechanisms remain unclear. Further characterization of the 9 top-hit drugs on the inhibition of VKD carboxylation suggests that warfarin, lansoprazole, and nitazoxanide mainly target vitamin K epoxide reductase (VKOR), whereas idebenone, clofazimine, and AM404 mainly target vitamin K reductase (VKR) in vitamin K redox cycling. The other 3 drugs mainly affect vitamin K availability within the cells. The molecular mechanisms underlying the inactivation of VKOR and VKR by these drugs are clarified. Results from both cell-based and animal model studies suggest that the anticoagulation effect of drugs that target VKOR, but not VKR, can be rescued by the administration of vitamin K. These findings provide insights into the prevention and management of drug-induced bleeding disorders. The established cell-based, high-throughput screening approach provides a powerful tool for identifying new vitamin K antagonists that function as anticoagulants.

Genetic predisposition to increased serum calcium, bone mineral density, and fracture risk in individuals with normal calcium levels: mendelian randomisation study.

OBJECTIVE: To determine if genetically increased serum calcium levels are associated with improved bone mineral density and a reduction in osteoporotic fractures. DESIGN: Mendelian randomisation study. SETTING: Cohorts used included: the UK Biobank cohort, providing genotypic and estimated bone mineral density data; 25 cohorts from UK, USA, Europe, and China, providing genotypic and fracture data; and 17 cohorts from Europe, providing genotypic and serum calcium data (summary level statistics). PARTICIPANTS: A genome-wide association meta-analysis of serum calcium levels in up to 61 079 individuals was used to identify genetic determinants of serum calcium levels. The UK Biobank study was used to assess the association of genetic predisposition to increased serum calcium with estimated bone mineral density derived from heel ultrasound in 426 824 individuals who had, on average, calcium levels in the normal range. A fracture genome-wide association meta-analysis comprising 24 cohorts and the UK Biobank including a total of 76 549 cases and 470 164 controls, who, on average, also had calcium levels in the normal range was then performed. RESULTS: A standard deviation increase in genetically derived serum calcium (0.13 mmol/L or 0.51 mg/dL) was not associated with increased estimated bone mineral density (0.003 g/cm2, 95% confidence interval -0.059 to 0.066; P=0.92) or a reduced risk of fractures (odds ratio 1.01, 95% confidence interval 0.89 to 1.15; P=0.85) in inverse-variance weighted mendelian randomisation analyses. Sensitivity analyses did not provide evidence of pleiotropic effects. CONCLUSIONS: Genetic predisposition to increased serum calcium levels in individuals with normal calcium levels is not associated with an increase in estimated bone mineral density and does not provide clinically relevant protection against fracture. Whether such predisposition mimics the effect of short term calcium supplementation is not known. Given that the same genetically derived increase in serum calcium is associated with an increased risk of coronary artery disease, widespread calcium supplementation in the general population could provide more risk than benefit.

Warfarin dose requirement in patients having severe thrombosis or thrombophilia.

AIMS: Warfarin dose requirement varies significantly. We compared the clinically established doses based on international normalized ratio (INR) among patients with severe thrombosis and/or thrombophilia with estimates from genetic dosing algorithms. METHODS: Fifty patients with severe thrombosis and/or thrombophilia requiring permanent anticoagulation, referred to the Helsinki University Hospital Coagulation Center, were screened for thrombophilias and genotyped for CYP2C9*2 (c.430C>T, rs1799853), CYP2C9*3 (c.1075A>C, rs1057910) and VKORC1 c.-1639G>A (rs9923231) variants. The warfarin maintenance doses (target INR 2.0-3.0 in 94%, 2.5-3.5 in 6%) were estimated by the Gage and the International Warfarin Pharmacogenetics Consortium (IWPC) algorithms. The individual warfarin maintenance dose was tailored, supplementing estimates with comprehensive clinical evaluation and INR data. RESULTS: Mean patient age was 47 years (range 20-76), and BMI 27 (SD 6), 68% being women. Forty-six (92%) had previous venous or arterial thrombosis, and 26 (52%) had a thrombophilia, with 22% having concurrent aspirin. A total of 40% carried the CYP2C9*2 or *3 allele and 54% carried the VKORC1-1639A allele. The daily mean maintenance dose of warfarin estimated by the Gage algorithm was 5.4 mg (95% CI 4.9-5.9 mg), and by the IWPC algorithm was 5.2 mg (95% CI 4.7-5.7 mg). The daily warfarin maintenance dose after clinical visits and follow-up was higher than the estimates, mean 6.9 mg (95% CI 5.6-8.2 mg, P < 0.006), with highest dose in patients having multiple thrombophilic factors (P < 0.03). CONCLUSIONS: In severe thrombosis and/or thrombophilia, variation in thrombin generation and pharmacodynamics influences warfarin response. Pharmacogenetic dosing algorithms seem to underestimate dose requirement.

VKORC1 and CYP2C9 Polymorphisms: A Case Report in a Dutch Family with Pulmonary Fibrosis.

Here, we describe a Dutch family with idiopathic pulmonary fibrosis (IPF). We hypothesized that there might be an association between the presence of Vitamin K epoxide reductase complex 1 (VKORC1) and/or cytochrome P450 2C9 (CYP2C9) variant alleles and the early onset of IPF in the members of this family. VKORC1 (rs9923231 and rs9934438) and CYP2C9 (rs1799853 and rs1057910) were genotyped in this family, which includes a significant number of pulmonary fibrosis patients. In all family members, at least one of the variant alleles tested was present. The presence of the VKORC1 variant alleles in all of the IPF cases and CYP2C9 variants in all but one, which likely leads to a phenotype that is characterized by the early onset and progressive course of IPF. Our findings indicate a role of these allelic variants in (familial) IPF. Therefore, we suggest that the presence of these variants, in association with other pathogenic mutations, should be evaluated during genetic counselling. Our findings might have consequences for the lifestyle of patients with familial IPF in order to prevent the disease from becoming manifest.

Missense mutation of VKORC1 leads to medial arterial calcification in rats.

Vitamin K plays a crucial role in the regulation of vascular calcifications by allowing activation of matrix Gla protein. The dietary requirement for vitamin K is low because of an efficient recycling of vitamin K by vitamin K epoxide reductase (VKORC1). However, decreased VKORC1 activity may result in vascular calcification. More than 30 coding mutations of VKORC1 have been described. While these mutations have been suspected of causing anticoagulant resistance, their association with an increase in the risk of vascular calcification has never been considered. We thus investigated functional cardiovascular characteristics in a rat model mutated in VKORC1. This study revealed that limited intake in vitamin K in mutated rat induced massive calcified areas in the media of arteries of lung, aortic arch, kidneys and testis. Development of calcifications could be inhibited by vitamin K supplementation. In calcified areas, inactive Matrix Gla protein expression increased, while corresponding mRNA expression was not modified. Mutation in VKORC1 associated with a limited vitamin K intake is thus a major risk for cardiovascular disease. Our model is the first non-invasive rat model that shows spontaneous medial calcifications and would be useful for studying physiological function of vitamin K.

Evaluation of oral anticoagulants with vitamin K epoxide reductase in its native milieu.

Warfarin, acenocoumarol, phenprocoumon, and fluindione are commonly prescribed oral anticoagulants for the prevention and treatment of thromboembolic disorders. These anticoagulants function by impairing the biosynthesis of active vitamin K-dependent coagulation factors through the inhibition of vitamin K epoxide reductase (VKOR). Genetic variations in VKOR have been closely associated with the resistant phenotype of oral anticoagulation therapy. However, the relative efficacy of these anticoagulants, their mechanisms of action, and their resistance variations among naturally occurring VKOR mutations remain elusive. Here, we explored these questions using our recently established cell-based VKOR activity assay with the endogenous VKOR function ablated. Our results show that the efficacy of these anticoagulants on VKOR inactivation, from most to least, is: acenocoumarol > phenprocoumon > warfarin > fluindione. This is consistent with their effective clinical dosages for stable anticoagulation control. Cell-based functional studies of how each of the 27 naturally occurring VKOR mutations responds to these 4 oral anticoagulants indicate that phenprocoumon has the largest resistance variation (up to 199-fold), whereas the resistance of acenocoumarol varies the least (<14-fold). Cell-based kinetics studies show that fluindione appears to be a competitive inhibitor of VKOR, whereas warfarin is likely to be a mixed-type inhibitor of VKOR. The anticoagulation effect of these oral anticoagulants can be reversed by the administration of a high dose of vitamin K, apparently due to the existence of a different enzyme that can directly reduce vitamin K. These findings provide new insights into the selection of oral anticoagulants, their effective dosage management, and their mechanisms of anticoagulation.

Pharmacogenetic variants and vitamin K deficiency: a risk factor or trigger for fibrosing interstitial pneumonias?

PURPOSE OF REVIEW: Fibrosing interstitial pneumonias are associated with various stages of fibrosis. The cause of this group of syndromes remains largely unknown. For most of these diseases, a genetic basis, environmental factors and certain triggers have been suggested as possible risk factors. Various studies have found an association between genetic polymorphisms, or the presence of certain variant alleles, and the occurrence and/or progression of interstitial pneumonias of unknown origin. An acute exacerbation of idiopathic pulmonary fibrosis shows characteristics of diffuse alveolar haemorrhage (DAH). DAH can be aggravated by vitamin K deficiency. This review deals with pharmacogenetic factors underlying interindividual differences of vitamin K status in patients with interstitial pneumonias and the possibilities for a personalized approach to patient management. RECENT FINDINGS: DAH has been associated with the presence of variant alleles in vitamin K epoxide reductase complex 1, cytochrome P450 (CYP)2C9 and CYP2C19 genes. Vitamin K deficiency has been associated with an increased risk for the development of DAH and progression and/or deterioration of interstitial pneumonias. This is in line with plausible pathophysiological mechanisms. However, clinical use should be confirmed. SUMMARY: DAH has been associated with vitamin K deficiency and suggested as potential trigger of fibrosing interstitial pneumonias. Information on genetic variation might benefit ongoing/new clinical trials, design of which should reflect needs to address relevance of testing gene variants. Whether vitamin K supplementation may prevent exacerbations or progression of interstitial pneumonias needs to be explored in future studies.

Genetic polymorphisms of pharmacogenomic VIP variants in the Yi population from China.

INTRODUCTION: Drug response and target therapeutic dosage are different among individuals. The variability is largely genetically determined. With the development of pharmacogenetics and pharmacogenomics, widespread research have provided us a wealth of information on drug-related genetic polymorphisms, and the very important pharmacogenetic (VIP) variants have been identified for the major populations around the world whereas less is known regarding minorities in China, including the Yi ethnic group. Our research aims to screen the potential genetic variants in Yi population on pharmacogenomics and provide a theoretical basis for future medication guidance. MATERIALS AND METHODS: In the present study, 80 VIP variants (selected from the PharmGKB database) were genotyped in 100 unrelated and healthy Yi adults recruited for our research. Through statistical analysis, we made a comparison between the Yi and other 11 populations listed in the HapMap database for significant SNPs detection. Two specific SNPs were subsequently enrolled in an observation on global allele distribution with the frequencies downloaded from ALlele FREquency Database. Moreover, F-statistics (Fst), genetic structure and phylogenetic tree analyses were conducted for determination of genetic similarity between the 12 ethnic groups. RESULTS: Using the χ2 tests, rs1128503 (ABCB1), rs7294 (VKORC1), rs9934438 (VKORC1), rs1540339 (VDR) and rs689466 (PTGS2) were identified as the significantly different loci for further analysis. The global allele distribution revealed that the allele "A" of rs1540339 and rs9934438 were more frequent in Yi people, which was consistent with the most populations in East Asia. F-statistics (Fst), genetic structure and phylogenetic tree analyses demonstrated that the Yi and CHD shared a closest relationship on their genetic backgrounds. Additionally, Yi was considered similar to the Han people from Shaanxi province among the domestic ethnic populations in China. CONCLUSIONS: Our results demonstrated significant differences on several polymorphic SNPs and supplement the pharmacogenomic information for the Yi population, which could provide new strategies for optimizing clinical medication in accordance with the genetic determinants of drug toxicity and efficacy.

Comparison of Aspirin and Naoxintong Capsule () with Adjusted-Dose Warfarin in Elderly Patients with High-Risk of Non-Valvular Atrial Fibrillation and Genetic Variants of Vitamin K Epoxide Reductase.

OBJECTIVE: To compared the therapeutic effect of a Chinese patent medicine Naoxintong Capsule (, NXT) and aspirin with adjusted-dose warfarin in Chinese elderly patients (over 65 years) with nonvalvular atrial fibrillation (NVAF) and genetic variants of vitamin K epoxide reductase (VKORC1), who are at high-risk of thromboembolism. METHODS: A total of 151 patients, with NVAF and AA genotype of VKORC1-1639 (a sensitive genotype to warfarin) and a CHA2DS2-VASc clinical risk score of 2 or above, were chosen for this study. Patients were randomized into two groups and orally treated with a combination of aspirin (100 mg/day) and NXT (1.6 g thrice a day) or adjusted-dose warfarin [international normalized ratio 2.0-3.0). The primary end points including ischemic stroke and death as well as the secondary end points including hemorrhage events were followed up for at least 1 year. RESULTS: Baseline clinical data and the rates of primary end points were similar between groups. However, the rate of serious bleeding (secondary event) in the combination therapy group was lower than that in the adjusted-dose warfarin group (0% vs. 7.9%, odds ratio: 0.921, 95% confidence interval: 0.862-0.984, P=0.028). CONCLUSIONS: Aspirin combined with NXT and warfarin displayed comparable rates of primary end point including ischemic stroke and all-cause death during the 1-year follow-up. However, as compared with warfarin, the combination therapy reduced the rate of serious bleeding. Therefore, aspirin combined with NXT might provide an alternative pharmacotherapy in preventing ischemic stroke for elderly patients with NAVF who cannot tolerate warfarin. (No. ChiCTR-TRC-13003596).

Comparative performance of pharmacogenetics-based warfarin dosing algorithms derived from Caucasian, Asian, and mixed races in Thai population.

AIM: This study was conducted to compare predictive accuracy of the available pharmacogenetics (PGx)-guided warfarin dosing algorithms derived from Caucasian, Asian, and mixed population to identify a suitable algorithm for Thai population. METHODS: Ten warfarin dosing algorithms derived from different population including Caucasian, East Asian, South-East Asian, and mixed races were selected and tested with clinical and genetic data of Thai patients. Comparative performances of these algorithms were tested using mean dose error (MDE) between actual warfarin maintenance dose (AWMD) and predicted dose generated by each dosing algorithm, and percentage of ideal dose prediction (IDP). Sensitivity analysis for predictive accuracy was also conducted by stratifying patients into low (AWMD ≤21 mg/wk), intermediate (AWMD >21 to <49 mg/wk), and high maintenance dose (AWMD ≥49 mg/wk) groups. RESULTS: Data of 165 patients were included for the analyses. Mean actual warfarin dose of the study population was 25.03 ± 10.53 mg/wk. Large variability of MDE, ranging from -12.11 to 11.24 mg/wk, among algorithms was observed. International Warfarin Pharmacogenetics Consortium, Gage et al, and Ohno et al algorithms had comparable performances to Sangviroon et al algorithm, as observed by MDE of <1 mg/wk with percentage of IDP ≥40%. Further sensitivity analyses among patients requiring low and intermediate maintenance doses confirmed such findings with IDP percentage ranging from 37.8% to 59.2%. Among high-dose group, only Ohno et al and Sarapakdi et al algorithms had acceptable performance. CONCLUSIONS: Warfarin PGx-guided dosing algorithms derived from large, mixed population performed comparably to Sangviroon et al algorithm. Certain algorithms should be avoided due to significant dose prediction error.

Comparison of Aspirin and Naoxintong Capsule () with Adjusted-Dose Warfarin in Elderly Patients with High-Risk of Non-Valvular Atrial Fibrillation and Genetic Variants of Vitamin K Epoxide Reductase / 中国结合医学杂志

<p><b>OBJECTIVE</b>To compared the therapeutic effect of a Chinese patent medicine Naoxintong Capsule (, NXT) and aspirin with adjusted-dose warfarin in Chinese elderly patients (over 65 years) with nonvalvular atrial fibrillation (NVAF) and genetic variants of vitamin K epoxide reductase (VKORC1), who are at high-risk of thromboembolism.</p><p><b>METHODS</b>A total of 151 patients, with NVAF and AA genotype of VKORC1-1639 (a sensitive genotype to warfarin) and a CHADS-VASc clinical risk score of 2 or above, were chosen for this study. Patients were randomized into two groups and orally treated with a combination of aspirin (100 mg/day) and NXT (1.6 g thrice a day) or adjusted-dose warfarin [international normalized ratio 2.0-3.0). The primary end points including ischemic stroke and death as well as the secondary end points including hemorrhage events were followed up for at least 1 year.</p><p><b>RESULTS</b>Baseline clinical data and the rates of primary end points were similar between groups. However, the rate of serious bleeding (secondary event) in the combination therapy group was lower than that in the adjusted-dose warfarin group (0% vs. 7.9%, odds ratio: 0.921, 95% confidence interval: 0.862-0.984, P=0.028).</p><p><b>CONCLUSIONS</b>Aspirin combined with NXT and warfarin displayed comparable rates of primary end point including ischemic stroke and all-cause death during the 1-year follow-up. However, as compared with warfarin, the combination therapy reduced the rate of serious bleeding. Therefore, aspirin combined with NXT might provide an alternative pharmacotherapy in preventing ischemic stroke for elderly patients with NAVF who cannot tolerate warfarin. (No. ChiCTR-TRC-13003596).</p>

Impact of Body Mass Index and Genetics on Warfarin Major Bleeding Outcomes in a Community Setting.

BACKGROUND: Several studies have demonstrated an association between body mass index (BMI) and warfarin therapeutic dose, but none evaluated the association of BMI with the clinically important outcome of major bleeding in a community setting. To address this evidence gap, we conducted a case-control study to evaluate the association between BMI and major bleeding risk among patients receiving warfarin. METHODS: We used a case-control study design to evaluate the association between obesity (BMI >30.0 kg/m2) and major bleeding risk among 265 cases and 305 controls receiving warfarin at Group Health, an integrated healthcare system in Washington State. Multivariate logistic regression was used to adjust for potential confounders derived from health plan records and a self-report survey. In exploratory analyses we evaluated the interaction between genetic variants potentially associated with warfarin bleeding (CYP2C9, VKORC1, and CYP4F2) and obesity on the risk of major bleeding. RESULTS: Overall, the sample was 55% male, 94% Caucasian, and mean age was 70 years. Cases and controls had an average of 3.4 and 3.7 years of warfarin use, respectively. Obese patients had significantly lower major bleeding risk relative to non-obese patients (odds ratio [OR] 0.60, 95% confidence interval [CI] 0.39-0.92). The OR was 0.56 (95% CI 0.35-0.90) in patients with ≥1 year of warfarin use, and 0.78 (95% CI 0.40-1.54) in patients with <1 year of warfarin use. An exploratory analysis indicated a statistically significant interaction between CYP4F2*3 genetic status and obesity (P = .049), suggesting a protective effect of obesity on the risk of major bleeding among those wild type for CYP4F2*3, but not among variants. CONCLUSIONS: Our findings suggest that BMI is an important clinical factor in assessing and managing warfarin therapy. Future studies should confirm the major bleeding associations, including the interaction between obesity and CYP4F2*3 status identified in this study, and evaluate potential mechanisms.

Uniparental disomy causes deficiencies of vitamin K-dependent proteins.

Essentials Vitamin K-dependent coagulant factor deficiency (VKCFD) is a rare autosomal recessive disorder. We describe a case of inherited VKCFD due to uniparental disomy. The homozygous mutation caused the absence of GGCX isoform 1 and overexpression of Δ2GGCX. Hepatic and non-hepatic vitamin K-dependent proteins must be assayed to monitor VKCFD treatment. SUMMARY: Background Inherited deficiency of all vitamin K-dependent coagulant factors (VKCFD) is a rare autosomal recessive disorder caused by mutations in the γ-glutamyl carboxylase gene (GGCX) or the vitamin K epoxide reductase gene (VKORC1), with great heterogeneity in terms of both clinical presentation and response to treatment. Objective To characterize the molecular basis of VKCFD in a Spanish family. Methods and Results Sequencing of candidate genes, comparative genomic hybridization and massive sequencing identified a new mechanism causing VKCFD in the proband. Uniparental disomy (UPD) of chromosome 2 caused homozygosity of a mutation (c.44-1G>A) resulting in aberrant GGCX splicing. This change contributed to absent expression of the mRNA coding for the full-length protein, and to four-fold overexpression of the smaller mRNA isoform lacking exon 2 (Δ2GGCX). Δ2GGCX might be responsible for two unexpected clinical observations in the patient: (i) increased plasma osteocalcin levels following vitamin K1 supplementation; and (ii) a mild non-bleeding phenotype. Conclusions Our study identifies a new autosomal disease, VKCFD1, caused by UPD. These data suggest that the Δ2GGCX isoform may retain enzymatic activity, and strongly encourage the evaluation of both hepatic and non-hepatic vitamin K-dependent proteins to assess differing responses to vitamin K supplementation in VKCFD patients.

Comparison of rivaroxaban mono-therapy and standard-therapy adjusted by CYP2C9 and VKORC1 genotypes in symptomatic pulmonary embolism.

RATIONALE: Pulmonary embolism (PE) is a life-threatening manifestation of venous thromboembolism. Rivaroxaban is an oral anticoagulant, which directly inhibits Factor Xa. The objective of the current study was, in comparison to the standard-therapy method, to investigate the potential of rivaroxaban to improve the treatment of patients with PE, and to reduce hemorrhage in the standard-therapy group through adjusting the dose of warfarin by CYP2C9 and VKORC1 genotypes. METHODS: Sixty-two PE patients with or without deep venous thrombosis (DVT) was randomized to rivaroxaban mono-therapy or standard-therapy with enoxaparin followed by vitamin K antagonist (VKA). Concentration of the anticoagulants was adjusted according to the results of CYP2C9 and VKORC1 genotypes in order to stabilize the international normalized rate (INR) at 2.0-3.0 range. Length of hospital stay at initial hospitalization was compared, therapeutic efficacy was examined by computed tomographic pulmonary angiography (CTPA) and ventilation/perfusion (V/Q) scan, and side-effect of anti-coagulants was monitored at 1-month, and 3- or 6-months follow-up check points. RESULTS: We found that, overall, patients who received rivaroxaban mono-therapy had a significantly shorter length of hospital stay compared with patients who received standard-therapy of enoxaparin followed by VKA (9.29±3.70 versus 11.38±3.12days, P=0.021). The therapeutic efficacy was of no marked difference between these two groups. However, after one month treatment, 50% (16/32) of the standard-therapy group had mild hemorrhage, which was significantly higher than that of rivaroxaban mono-therapy group (16.7%, 5/30, P=0.006). Moreover, a significantly higher rate in the standard-therapy group (22.2% versus 3.4%, P=0.032) was found after 3 or 6months therapy. Major bleeding was slightly but not significantly higher in the standard-therapy group than that in the rivaroxaban therapy group. In addition, 2 (6.3%) patients died from Life-threatening bleeding in the standard-therapy group. CONCLUSION: Findings of the current study suggested that rivaroxaban mono-therapy result in shorter hospital stay compared to the standard-therapy. Implication of CYP2C9 and VKORC1 genotypes in determining dose of warfarin, however, remains to be further examined in larger cohort studies.

An expanded pharmacogenomics warfarin dosing table with utility in generalised dosing guidance.

Pharmacogenomics (PGx) guided warfarin dosing, using a comprehensive dosing algorithm, is expected to improve dose optimisation and lower the risk of adverse drug reactions. As a complementary tool, a simple genotype-dosing table, such as in the US Food and Drug Administration (FDA) Coumadin drug label, may be utilised for general risk assessment of likely over- or under-anticoagulation on a standard dose of warfarin. This tool may be used as part of the clinical decision support for the interpretation of genetic data, serving as a first step in the anticoagulation therapy decision making process. Here we used a publicly available warfarin dosing calculator (www.warfarindosing.org) to create an expanded gene-based warfarin dosing table, the CPMC-WD table that includes nine genetic variants in CYP2C9, VKORC1, and CYP4F2. Using two datasets, a European American cohort (EUA, n=73) and the Quebec Warfarin Cohort (QWC, n=769), we show that the CPMC-WD table more accurately predicts therapeutic dose than the FDA table (51 % vs 33 %, respectively, in the EUA, McNemar's two-sided p=0.02; 52 % vs 37 % in the QWC, p<1×10(-6)). It also outperforms both the standard of care 5 mg/day dosing (51 % vs 34 % in the EUA, p=0.04; 52 % vs 31 % in the QWC, p<1×10(-6)) as well as a clinical-only algorithm (51 % vs 38 % in the EUA, trend p=0.11; 52 % vs 45 % in the QWC, p=0.003). This table offers a valuable update to the PGx dosing guideline in the drug label.

Development and Comparison of Warfarin Dosing Algorithms in Stroke Patients.

PURPOSE: The genes for cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase complex subunit 1 (VKORC1) have been identified as important genetic determinants of warfarin dosing and have been studied. We developed warfarin algorithm for Korean patients with stroke and compared the accuracy of warfarin dose prediction algorithms based on the pharmacogenetics. MATERIALS AND METHODS: A total of 101 patients on stable maintenance dose of warfarin were enrolled. Warfarin dosing algorithm was developed using multiple linear regression analysis. The performance of all the algorithms was characterized with coefficient of determination, determined by linear regression, and the mean of percent deviation was used to predict doses from the actual dose. In addition, we compared the performance of the algorithms using percentage of predicted dose falling within ±20% of clinically observed doses and dividing the patients into a low-dose group (≤3 mg/day), an intermediate-dose group (3-7 mg/day), and high-dose group (≥7 mg/day). RESULTS: A new developed algorithms including the variables of age, body weight, and CYP2C9 and VKORC1 genotype. Our algorithm accounted for 51% of variation in the warfarin stable dose, and performed best in predicting dose within 20% of actual dose and intermediate-dose group. CONCLUSION: Our warfarin dosing algorithm may be useful for Korean patients with stroke. Further studies to elucidate clinical utility of genotype-guided dosing and find the additional genetic association are necessary.