A fusion of the androgen-responsive transmembrane protease serine 2 (TMPRSS2) and the v-ets erythroblastosis virus E26 oncogene homolog (ERG) is found in approximately 50% of prostate cancer cases, making it the most common genetic aberration in PCa (Tomlins et al. 2005, Cancer Genome Atlas Research 2015). The gene discussed is TMPRSS2; the disease is posterior cortical atrophy.