PCa, prostate cancer;<br>PSA, prostate-specificantigen;<br>DRE, digital rectal examination;<br>TRUS, transrectal ultrasound;<br>NO, nitric oxide;<br>NOS, nitric oxide synthase;<br>nNOS, NOS1,neuronal NOS;<br>iNOS, NOS2, inducible NOS;<br>eNOS, NOS3, endothelialNOS;<br>BPH, benign prostatic hyperplasia;<br>fPSA, free PSA;<br>TPSA,total PSA;<br>fPSA%, percentage of free PSA;<br>f/T PSA, free/totalPSA ratio;<br>EDTA, ethylene diamine tetraacetic acid;<br>HW, Hardy-Weinberg Balance Test;<br>HT, hypertension;<br>DM, diabetes mellitus. This evidence concerns the gene KLK3 and benign prostatic hyperplasia.