Current practices often use a threshold of 4 ng/mL to trigger further evaluation, PSA levels between 4 and 10 ng/mL, often considered the ‘borderline or grey zone’ have a 25% risk of developing prostate cancer [4], while levels greater than 10 ng/mL indicate an over 50% risk of cancer [5]. Here, KLK3 is linked to Familial prostate cancer.