VKORC1 — warfarin sensitivity
One copy of the VKORC1 -1639G>A high-sensitivity variant detected.
You have one copy of the high-sensitivity version of the VKORC1 gene.
Intermediate warfarin sensitivity. Lower warfarin doses are typically needed to reach a therapeutic INR.
You're more sensitive than average to the blood-thinner warfarin. If you ever take it, your doctor will use a lower dose to get to the same level of blood-thinning.
What this means
VKORC1 produces the enzyme that recycles vitamin K, which warfarin inhibits. The -1639G>A variant in the gene's promoter reduces enzyme expression — less enzyme means warfarin's effect is amplified. Carriers need less warfarin to achieve the same INR. Combined with CYP2C9 genotype, this explains a substantial fraction of inter-individual warfarin dose variability.
VKORC1 makes the enzyme that recycles vitamin K in your body — and the blood-thinner warfarin works by blocking that enzyme. This version of the gene produces less of the enzyme to begin with, so warfarin's effect is amplified. People with this version need less warfarin to get the same amount of blood-thinning. Combined with the CYP2C9 gene, VKORC1 explains a big chunk of why different people need very different warfarin doses. This is mostly relevant if you're prescribed warfarin — newer blood-thinners like apixaban and rivaroxaban don't depend on this gene.
Caveats
- Most relevant if warfarin is prescribed; not relevant for DOAC anticoagulants.
- INR monitoring is still essential even with genotype-guided dosing.
- Variant frequency varies by ancestry; East Asian populations have the highest frequency.