KLK3 and Familial prostate cancer: The SNP rs2735839 is located near the KLK3 locus encoding PSA and has been previously reported to influence PSA levels in both healthy individuals and prostate cancer.29 Carriers of the major allele (G) have been shown to exhibit raised PSA expression, and thereby contemporary PSA screening could lead to overrepresentation of rs2734839 carriers in prostate cancer patients.46,47 This detection bias could result in an inverse association with aggressive status.