The incidence of prostate cancer when 1-PSA is less than 4.0 ng/mL is 6.1 per 1000 person-years (calculated using the incidence rate of prostate cancer of group c and f in Supplementary Table S4 [data not shown]), and the incidence of prostate cancer when 2-PSA is higher than 1-PSA is 66.9 per 1000 person-years, which is approximately 10 times higher (Supplementary Table S4). Here, KLK3 is linked to Familial prostate cancer.