KLK3 and posterior cortical atrophy: The ratio of free PSA/total PSA significantly declined in the PCa group compared with all other groups, which is consistent with a clinical study by Etzioni et al. (2004), and Catalona et al. (1998), who found that serum PSA in PCa cases increase and free PSA decreases in comparison to patients with benign prostatic hyperplasia; hence, a high ratio was seen in the control group [23, 24].