Genetic alterations in paediatric high grade astrocytomas

Paediatric high grade astrocytomas (HGA) are diffusely infiltrative and highly aggressive brain tumours that account for nearly 20% of all central nervous system tumours in children. They are classified as anaplastic astrocytoma (WHO grade III) and glioblastoma (WHO grade IV). Grade IV HGAs that are centred in the pons and diffusely involve the brainstem are referred to as Diffuse Intrinsic Pontine Gliomas (DIPGs). This chapter describes some of the most common genetic alterations identified in paediatric HGAs, and focuses on recent findings which underscore the major differences between adult and paediatric HGAs as well as the significance of epigenetic dysregulation during tumourigenesis. The diagnostic and prognostic utility of screening for various genetic alterations is also discussed.