الفهرس 
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Abstract
Warfarin remains the most commonly prescribed oral anticoagulant for the management of thromboembolic disorders. It exerts its anticoagulant effect by numerous mechanisms through inhibition of vitamin K epoxide reductase, and attenuating vitamin K-dependent -carboxylation of coagulation factors II, VII, IX and, X. However, dosing remains challenging due to narrow therapeutic range of warfarin and highly variable clinical response. These dosing challenges usually result in a high incidence of adverse effects (thrombosis and bleeding) and an increased burden to the patient (e.g. more frequent monitoring), which impacts the quality of life and results in treatment discontinuation of an otherwise highly efficacious drug. Part of the variability in warfarin responsiveness is related to host characteristics including age, sex, ethnicity, weight and body mass index and environmental factors such as diet and the intake of interacting drugs. Genetic polymorphism has also been reported to modulate warfarin responsiveness and sensitivity. Genetic variants affect the efficacy of warfarin either by a pharmacokinetic or pharmacodynamic mechanism. At least 30 genes play a role in the anticoagulation mechanism mediated by warfarin, including vitamin K epoxide reductase complex subunit 1 (VKORC1), cytochrome P450-2C9 (CYP2C9), cytochrome P450-4F2 (CYP4F2), g-glutamyl carboxylase (GGCX), calumenin (CALU), epoxide hydrolase 1 (EPHX), APOE, CYP2C8, CYPP1A2, CYP2C19, and CYP3A5, factor VII (FVII) and factor IX (F IX) genes. FVII induces coagulation and hemostasis in the extrinsic coagulation pathway and initiates key pathogenetic mechanisms in cell proliferation and invasion by interacting with TF, an essential cofactor of FVII activity. FVII gene polymorphisms may alter the responsiveness of warfarin therapy. Guanine to thymine (G/T) base substitution at the -401st position in the promoter region of FVII gene leads a decreased gene transcription and lower plasma FVII level and guanine to adenine (G/A) base substitution at the -402nd position in the same area increases the gene transcription and the FVII level. Together both polymorphisms are responsible for 18% and 28% of the variation in the plasma concentration and coagulation activity of FVII, respectively. By combining host, environmental and genetic markers into a single model, some 50360% of the variability in warfarin maintenance dose could be accounted for. Therefore, the dosage should be tailored to target INR and warfarin personalization approaches have to be followed. Still, there is no accurate way to determine the warfarin dose to lower the risk of bleeding. Therefore, it is helpful to increase the number of candidate genes affecting oral anticoagulants. This study aimed to clarify the impact of FVII polymorphism on the extent of anticoagulation exerted by warfarin therapy. The present study was conducted on thirty (30) patients on warfarin therapy with INR 2-3. All patients were subjected to thorough history taking [age, gender, clinical indications and dose of warfarin (marevan)]. Laboratory investigations included prothrombin time (PT), CBC, factor VII activity by coagulometric method, plasma warfarin level measured by high performance liquid chromatography (HPLC) and detection of FVII polymorphism (-401 G/T and -402 G/A) by PCR. Summary of our results: • Out of 30 patients, 18 (60%) of them were males and 12 (40%) were females (male to female ratio is 3:2). The mean age of the patients was 63.63± 8.89 years (range 26- 79 years). Average warfarin dose requirements ranged from 3- 14mg / day (5.85± 2.68). Twenty-one 21 patients (70 %) were taking warfarin anticoagulant for cardiac causes [12 patients (40%) with atrial fibrillation (AF), 8 patients (26.7%) had coronary artery disease (CAD), and 1 patient (3.3%) with mitral valve replacement (MVR), 2 patients (6.7%) for orthopedic causes and 7 patients (23.3%) for vascular causes, 5 patients (16.7%) with deep vein thrombosis (DVT), 1 patient (3.3%) with pulmonary embolism (PE) and 1 patient (3.3%) with stroke. • Regarding CBC, the range of white blood cell counts (WBCs) was 2.36- 12.18 x 103/µL with mean value 6.69 ± 2.15 x 103/µL, red blood cell counts (RBCs) range was 3.26- 5.32 x 106/µL with mean value 4.11± 0.7 x 106/µL, and platelet counts (PLT) range was 140- 355 x 103/µL with mean value 217.63± 61.05 x 103/µL and the range of hemoglobin was 7.3- 15.4 g/dl. • As for coagulation indicators, the mean prothrombin activity (PT activity, %) was 30.1 ± 4.24 %, the mean prothrombin time (PT time sec,) was 25.1 ± 3.27 second, and INR was 2.32 ± 0.31. The mean plasma warfarin level was 0.4± 0.16 µg/mL (0.2- 0.7 µg/mL) and the mean FVII coagulant activity (FVII:c, %) was 27.78± 10.29 % (5.20- 49.50 %). Warfarin sensitivity index (WSI) was calculated as INR value per warfarin dose and ranged from 0.14 to 1 with mean value 0.47± 0.18. • Genotype frequency (distribution) was as follows: 17 patients [11 (36.7%) heterozygotes and 6 (20%) homozygotes] showed the A-402 allele and 13 (43%) patients had the (wild type) while 10 patients [3 (10%) heterozygotes and 7 (23.3%) homozygotes] showed the T-401 allele and 20 (66.7%) patients had the G-401 allele. • The frequency of the G-402 allele was 0.62 and of the A-402 allele was 0.38 while that of the G-401 allele was 0.72 and of the T-401 allele was 0.28. The distribution of FVII -402 genotypes were in Hardy-Weinberg equilibrium. However, the frequency of FVII -401 genotypes was deviated significantly from the expected Hardy-Weinberg distribution. • In patients with FVII -402 G/A, the median age was 64 years in heterozygous, 66 years in homozygous and 64 years in wild type. Males were 64%, 83% and 46% in heterozygous, homozygous and wild type respectively. There is no statistical evidence that age and sex are significantly associated with various FVII -402 G/A genotypes. • In patients with FVII -401 G/T, the median age was 63 years in heterozygous, 64 years in homozygous and 65 years in wild type. Males were 66.7%, 28.6% and 15% in heterozygous, homozygous and wild type respectively. There is no statistical evidence that age and sex are significantly associated with various FVII -401 G/T genotypes. • None of the CBC characteristics in patients with various FVII -402 and - 401 genotypes was statistically different between various FVII -402 and -401 genotypes. • As regard FVII -402 G/A, the median PT time (sec) was statistically significantly lower in homozygous mutant (21.7 sec) than heterozygous. Also, it was lower than that of wild type but this was not statistically significant. The median PT time (sec) was lower in wild type (25.2 %) than heterozygous (26.1%) but this was not statistically significant. • As regard FVII -402 G/A, the median PT activity (%) was statistically significantly higher in homozygous mutant (35.5%) than heterozygous mutant (28.5%). Also, it was higher than that of wild type but this was not statistically significant. The median PT activity (%) was higher in wild type (30.8 %) than heterozygous (28.5%) but this was not statistically significant. • The median INR was 2.34 ranging from 2 to 3 in heterozygous, 2.1 ranging from 2 to 3 in homozygous and 2.32 ranging from 2 to 3 in wild type. However, the median INR was not statistically different between various FVII -402 G/A genotypes. • As regard FVII -402 G/A, the median WSI was higher in wild type (0.61) than heterozygous (0.39) and homozygous mutant (0.27). However, the median WSI was statistically significantly different only between wild type and homozygous mutant. • As regard FVII -402 G/A, the median marevan dose (mg) was statistically significantly lower in wild type (4.0 mg) than homozygous mutant (7.5 mg) and heterozygous (6.0 mg). • As regard FVII -402 G/A, The median plasma warfarin level (µg/mL) was not statistically significant between heterozygous, homozygous mutant and wild type. • The median FVII:c (%) was higher in homozygous mutant (34.3%) than heterozygous (27%) and wild type (23.8%). However, it was not statistically significant between various factor VII- 402 genotypes • As regard FVII -401 G/T, the median PT activity (%), PT time (sec) and INR was nearly the same among the different FVII- 401 G/T genotypes. • As regard FVII -401 G/T, the median WSI was lower in wild type (0.39) than heterozygous (0.57) and homozygous mutant (0.67). However, the median WSI was statistically significantly different between wild type as compared with homozygous and heterozygous genotypes. • As regard FVII -401 G/T, the median marevan dose (mg) was statistically significantly higher in wild type (6.25 mg) than homozygous mutant (3.0 Summary and Conclusions 108 mg). The median marevan dose was higher in heterozygous (4.5 mg) than homozygous mutant. However, there was no statistically significant difference in the median marevan dose between heterozygous and homozygous mutant. • As regard FVII -401 G/T, the median plasma warfarin level (µg/mL) was not statistically significant between heterozygous, homozygous mutant and wild type. • The median FVII:c (%) was higher in wild type (28.5%) than heterozygous (23.5%) and homozygous mutant (23.3%). However, it was not statistically significant different between various FVII- 401 G/T genotypes. • Bivariate analysis of factors (age, sex, INR, clinical conditions) that can modulate marevan dose other than FVII genotypes showed that only age is significantly associated with marevan dose. The possibility that different FVII genotypes (-402 G/A and -401 G/T genotypes) can affect marevan was further investigated in a multiple linear regression model, adjusted for age, sex, INR and clinical conditions. A stepwise analysis revealed the independent nature of only FVII -401 G/T genotypes (Adjusted R2: 0.227; p=0.005).