KLK3 and Familial prostate cancer: Generally, a level <2.5 ng/mL PSA is considered normal (safe group), 2.6–4.0 ng/mL PSA requires consultation with a doctor (safe for the most group), 4–10 ng/mL PSA indicates a 25% chance of having prostate cancer (suspect group), and patients with >10 ng/mL PSA in their blood must undergo further clinical tests because they have a 50% probability of having this disease [7].