In early stages of PCa, DNA hypermethylation occurs in many genes, such as glutathione-S-transferase pi 1 (GSTP1, which belongs to the GST family of detoxification enzymes), PTEN (the most frequently lost tumour suppressor gene in Pca), and Ras association domain family protein 1, isoform A (RASSF1A), indicating that epigenetic alterations are early events in Pca [130,144,145,146,147]. The gene discussed is PTEN; the disease is posterior cortical atrophy.