Currently, the only widely-used routine clinical screening biomarker for PCa is serum prostate-specific antigen (PSA), which has been garnering the criticism of low diagnostic specificity (25–40%) within the so-called “PSA grey zone” and resulting in a substantial increase in benign prostatic hyperplasia (BPH) or clinically indolent disease unnecessary biopsies (4, 5). The gene discussed is KLK3; the disease is benign prostatic hyperplasia.