This test combines a total of four different kallikrein proteins: total PSA, free PSA, intact PSA, and human kallikrein 2 (hK2) [31] with patient age, DRE results (abnormal or normal), and results of prior prostate biopsies to provide a probability score of 0–100% of detecting clinically significant prostate cancer. This evidence concerns the gene KLK3 and Familial prostate cancer.