Novel genetic variants of the Plasminogen Activator, Urokinase (PLAU) gene are described. Various genotypes, haplotypes, and haplotype pairs that exist in the general United States population are disclosed for the PLAU gene. Compositions and methods for haplotyping and/or genotyping the PLAU gene in an individual are also disclosed. Polynucleotides defined by the haplotypes disclosed herein are also described.