Disclosed herein are methods for determining whether a PAR4 inhibitor should be administered to a human subject, the methods comprising administering a PAR4 inhibitor to a subject determined to have a “G” allele for a single-nucleotide polymorphism (SNP) at rs773902, and not administering a PAR4 inhibitor to a subject determined to have an “A” allele for the SNP at rs773902. A genotyping assay can be used to determine the SNP.
