Gudmundsson [9] identified four SNPs that were principally associated with PSA levels rather than with prostate cancer risk in a genome-wide association study (GWAS) on serum PSA levels in Icelandic men not diagnosed with prostate cancer (PSA-SNPs: TERT rs2736098, FGFR2 rs10788160, TBX3 rs11067228, KLK3 rs17632542). The gene discussed is KLK3; the disease is Familial prostate cancer.