Quantitative RT-PCR (qRT-PCR) was used to verify the expression of five NanoString gene-probes: (i) KLK3 a prostate-specific gene used for normalisation in the Progensa PCA3 test [38]; (ii) RPLP2, a gene used for data normalisation in construction of the PUR signatures [10]; three commonly used PCa-related genes: (iii) PCA3 (selected in Boruta analysis multivariate analysis for association with PCa—see below), (iv) OR51E2 (aka PSGR Prostate-Specific G-Protein Coupled Receptor) (Boruta selected) and (v) FOLH1 (aka PSMA, prostate-specific membrane antigen). The gene discussed is OR51E2; the disease is posterior cortical atrophy.