Glioblastoma (GBM) (grade IV astrocytoma), for example, is characterized by mutations in PTEN and epidermal growth factor receptor (EGFR) amplification in adults [12]; the pediatric counterpart more frequently presents mutations in the N-terminal tail of the histone variant 3.3 [13], in platelet-derived growth factor (PDGF) and its receptor (PDGFR) [14]. The gene discussed is PTEN; the disease is glioblastoma.