Warfarin CYP2C9 and VKORC1 Sensitivity Test

Warfarin is an anticoagulant. It reduces the activity of the vitamin K dependent clotting factors to stop the blood from clotting. It has the measure role in thrombotic disorders. The dose of the drug from person to person based on the INR response of the patient. As per the result of it the condition of the patient is treated. Genotype CYP2C9 and VKORC1 of the patient can be determined to optimise the dose of the warfarin. The genotype CYP2C9 encodes an enzyme which monitors the metabolism of warfarin. Many variants CYP2C9 alleles might be present in the body which are associated with the reduced enzyme activity and lower clearance rate of the warfarin. Patients with at least one allele of the CYP2C9 have reduced metabolism of warfarin leading to the higher concentration of it. The target of the warfarin, vitamin K epoxide reductase enzyme, is encoded by VKORC1 gene. Patients with -1639G>A polymorphism at the promoter region of the VKORC1 gene are more sensitive to the warfarin drug and require lower dose of it.

Before starting the warfarin doses, the patient can be recommended to undergo the genetic testing for the VKORC1 and CYP2C9 genes. In order to carry out the test, blood sample of the patient is collected and DNA is extracted from it in order to perform the genetic testing.

The test is done to know the suitable dose of warfarin for the patient. Warfarin is given to reduce the risks of the stroke and heart attack. It is given in case of treatments of the clots with heart valve replacement or atrial fibrillation. It is recommended in case of treatment of the clots to be done in the lower part of the body and in the lungs. Warfarin can be used as a part of the combination therapy as well. Warfarin is also used to treat the blood clot as in case of the thrombosis

Genetic testing for CYP2C9 and VKORC1 genes are done. The variants that are generally tested for along with CYP2C9 and VKORC1 are CYP2C9•2, CYP2C9•3 and -1639G>A. These variants are used in the FDA table in order to guide the doctor for the required doses of the warfarin. Other variants also have role in the vitamin-K cycle like CYP2C9•6 and CYP2C9•8, alleles and the genes CYP4F2, GGX and EPHX1 but aren’t frequently tested for the warfarin dose