To observe natural PSA fluctuation by age, we constructed PSA plots showing 25th, 50th, 75th, 90th, and 95th percentile PSA values by age using 262,639 PSA measurements taken in healthy men (i.e., excluding 434 men who were diagnosed with prostate cancer) (Fig. 1). The gene discussed is KLK3; the disease is Familial prostate cancer.