A genotype will be provided for each of the 11 SNPs tested in this analysis. The genotypes will indicate whether the individual has the homozygous wild type, heterozygous or homozygous variant/mutant allele at each position. This information is entered into the WarfarinDosing.org algorithm, which calculates an initial warfarin dose requirement and an estimated daily warfarin dose requirement, in order to achieve the target international normalized ratio (INR).