RhyMA Test Warfarin_Strip Test - 20 Strips
 
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PRINCIPLE OF THE TEST

RhyMA TEST WARFARIN RESISTANCE is a multiparametric test that it’s able to identify the following mutations:

1. VKORC1 (1639G>A)

2. CYP2C9*2 (430C>T)

3. CYP2C9*3 (1075>T)



 

 

Warfarin (also known under the brand names Coumadin, Jantoven, Marevan, and Waran) is an anticoagulant. It was initially marketed as a pesticide against rats and mice, and is still popular for this purpose, although more potent poisons such as brodifacoum have since been developed. A few years after its introduction, warfarin was found to be effective and relatively safe for preventing thrombosis and embolism (abnormal formation and migration of blood clots) in many disorders.

 

Cytochrome P450 isoenzyme 2C9 (CYP2C9) is the main enzyme responsible for metabolism and clearance of S-warfarin (the most potent enantiomer). Individuals with one of the common variants (CYP2C9*2 or CYP2C9*3) will have decreased enzyme activity, which results in reduced metabolism and slower clearance of S-warfarin. These patients are three to four times more likely to bleed. They take more time to reach stable doses and have at least a 15% lower maintenance dose requirement, or about 2 mg lower on average, than patients without gene variations. The CYP2C9 variants are more common in whites than blacks, and the frequency can be as high as 20%. Therefore, a large number of patients may benefit from clinical testing of these variants.

 

Warfarin’s main action is to inhibit vitamin K epoxide reductase (VKOR), a multiprotein enzyme that makes vitamin K available in a form necessary for synthesis of several downstream clotting factors. Inhibition of VKOR results in lower levels of vitamin K dependent clotting factors and a reduced tendency to clot. Like variants of CYP2C9, individuals with genetic variations in the VKORC1 gene, such as -1639/3673, are more sensitive to the effects of warfarin. They have a reduced warfarin dose requirement and spend less time in the therapeutic range. Patients with variations in this gene may need at least a 20% reduction in warfarin dose. On average, this amounts to an average difference of about 3 mg for patients with different genotypes. VKORC1 variants have been estimated to occur in 14% to 37% of whites and blacks and in up to 89% of Asians.




 

 
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