The invention provides novel polynucleotides and polypeptides associated with the incidence of PPAR-agonist induced edema. The invention also provides polynucleotide fragments corresponding to the genomic and/or coding regions of these polynucleotides which comprise at least one polymorphic locus per fragment. Allele-specific primers and probes which hybridize to these regions, and/or which comprise at least one polymorphic locus are also provided. The polynucleotides, primers, and probes of the present invention are useful in phenotype correlations, medicine, and genetic analysis. Also provided are vectors, host cells, antibodies, and recombinant and synthetic methods for producing said polynucleotides and/or polypeptides. The invention further relates to diagnostic and therapeutic methods for applying these novel polynucleotides and polypeptides to the diagnosis, treatment, and/or prevention of various diseases and/or disorders, particularly PPAR-agonist induced edema or related indications. The invention further relates to screening methods for identifying agonists of PPAR proteins with decreased risk of inducing peripheral edema in patients.