KLK3 and Familial prostate cancer: Using the combined effect of the four PSA-SNPs to genetically correct measured PSA, they found that 6–7% of Icelandic men undergoing PSA-based prostate cancer screening would have at least one PSA measurement reclassified with respect to whether they should undergo a biopsy (using a threshold for biopsy of PSA≥4ng/mL).