The present invention is directed to BAP28 polypeptides. BAP28 cDNA sequences encoding BAP28 polypeptides, to the genomic DNA sequence of the BAP28 gene as well as to regulatory regions located at the 5'- and 3'-ends of the BAP28 coding region. The invention also deals with antibodies directed specifically against such polypeptides that are useful as diagnostic reagents. The invention further encompasses biallelic markers of the BAP28 gene useful in genetic analysis. The invention concerns an association of the BAP28-related biallelic markers with prostate cancer. Therefore, the invention contemplates the diagnostic and treatment methods of prostate cancer.