A 62-year-old otherwise healthy Caucasian man (80 kg, 173 cm, body mass index [BMI] 26.7) was found to have clinical stage T2c prostate cancer as transrectal ultrasound (TRUS)-guided biopsy revealed Gleason 3 + 4 = 7, and Prostate-specific antigen (PSA) was 13.5 ng/dL). Here, KLK3 is linked to Familial prostate cancer.