The final MPS2 model included clinical variables and the 17 most informative markers, including 13 from the discovery analysis (4 high-grade cancer–specific genes [APOC1, B3GNT6, NKAIN1, and SCHLAP1] and 9 cancer-specific genes [PCGEM1, SPON2, TRGV9, PCA3, OR51E2, CAMKK2, TFF3, PCAT14, and TMSB15A]), 4 curated markers (HOXC6, ERG, TMPRSS2:ERG, and KLK4), plus the reference gene KLK3 (eTable in Supplement 3). The gene discussed is KLK3; the disease is cancer.