Warfarin acts by inhibiting the activity of the VKORC1 protein, which helps to produce functional clotting factors. There is a variant in the VKORC1 gene that lowers the dose of warfarin required for treatment, and individuals with this variant have increased risk of bleeding when they are treated with warfarin. This variant is found 1639 base pairs upstream of the translational start site. This variant likely:. a. decreases the activity of the VKORC1 protein. b. increases the activity of the VKORC1 protein. c. decreases expression of the VKORC1 gene. d. increases expression of the VKORC1 gene.

The correct answer - c. decreases expression of the VKORC1 gene.

Explanation:

Mutation of Guanine nucleotide into Adenosine is the reason for this particular type of mutation. This mutation expresses the less expression of the VKORC1 protein.

The mutation results in a decrease in the affinity of the binding site of the transcription factor which causes less expression. Since the VKORC1 protein is less in the body so Warfarin doses are decreased  

Thus, the correct answer is - decreases expression of the VKORC1 gene.

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.