The TMPRSS-ERG gene fusion event is the most common in PCa and occurs more frequently in PZ tumours compared with TZ tumours.32–34 Gene expression studies have also shown distinct transcriptomic profiles between the zones, for example, non-malignant PZ tissue has higher de novo lipid biosynthesis,35 potentially providing a better niche for PCa tumorigenesis. The gene discussed is ERG; the disease is posterior cortical atrophy.