Frequency of Common VKORC1 Polymorphisms and Their Impact on Warfarin Dose Requirement in Pakistani Population.

Polymorphisms in vitamin K epoxide reductase complex subunit 1 (VKORC1) gene lead to interindividual variability in warfarin dose requirement. The characterization of genotype frequency distribution is required in different populations for construction of customized dosing algorithms to enhance the efficacy and reduce the toxicity of warfarin therapy. This study was carried out in Pakistani population to evaluate the contribution of common VKORC1 polymorphisms to warfarin therapy. A total of 550 stable patients taking warfarin were enrolled after medical history, physical examination, and laboratory investigations. Single blood sample was collected after informed consent. Genomic DNA was extracted and genotype analysis for VKORC1 1173C>T and VKORC1-1639G>A polymorphisms was done by polymerase chain reaction-restriction fragment length polymorphism assay. A number of samples were also analyzed by direct DNA sequencing for validation of results. Data were analyzed using SPSS version 20. Genotype frequency distributions of VKORC1 1173C>T and VKORC1-1639G>A were found to be different from other populations. Both of these polymorphisms did not demonstrate significant effect on warfarin dose requirement. Although Cytochrome P450 2C9 (CYP2C9) and VKORC1 polymorphisms together attributed only 3.8% variability in warfarin dose but it was statistically significant ( p value = .004). It is concluded that there is a need to study genotype frequency distribution and their effect on warfarin dose variability among different populations due to diversity in outcome. At the same time, no effect on warfarin dose variation explained by VKORC1 polymorphisms and small variability explained by studied genotypes stresses the need for exploration of more genetic and nongenetic factors in Pakistani population.

Study of the effect of antiviral therapy on homocysteinemia in hepatitis C virus- infected patients.

BACKGROUND: Hepatitis C virus (HCV) infection is one of the leading causes of chronic liver disease (CLD). About 80% of those exposed to the virus develop a chronic infection. Hyperhomocysteinemia, which is an independent risk factor for atherosclerotic vascular disease and thromboembolism, may develop in HCV-infected patients although altered alanine amino transferase (ALT) enzyme levels are generally associated with damage to liver cells. The gold standard therapy for chronic hepatitis C patients is pegylated interferon combined with an anti-viral drug (ribavirin). The current study aimed to investigate the effect of antiviral therapy on plasma homocysteine (Hcy) levels in HCV patients in addition to other parameters. METHODS: 532 HCV-infected patients and 70 healthy controls were recruited for the study. All patients were subjected to laboratory investigations including HCV-RNA levels, complete blood cell counts, serum levels of homocysteine, ALT, alkaline phosphatase (ALP), lipid profile and liver ultrasonographic examination. The outcome of treatment with pegylated interferon α plus ribavirin treatment and sustained virologic response (SVR) was determined 6-9 months post-therapy. RESULTS: Hyperhomocysteinemia was found in 91.35% of HCV-infected patients. The difference in plasma Hcy concentrations reached statistical significance between the patient and control groups. ALT, cholesterol and triglycerides (TGs) levels were found higher than normal in the patients group. After receiving a combined therapy for 24 weeks, 43.66% patients showed an SVR (responders); 30.98% patients were non-responders while 25.35% patients initially responded to therapy but again retrieved positive status of HCV infection six months post-therapy (relapse-cirrhotic patients). The mean levels of plasma Hcy, ALT and ALP were significantly reduced in responders within 10 weeks of therapy when compared with non-responders and relapse-cirrhotic patients. CONCLUSION: Elevated homocysteine levels in serum due to HCV infection can be reduced to normal range with the standard interferon α plus ribavirin treatment. This study highlights the significance of the measurement of serum homocysteine levels in the diagnosis and monitoring of HCV infection treatment in addition to other laboratory parameters.