High grade gliomas (HGG) are a group of tumours that can occur in any location in the central nervous system (CNS). They are associated with a very poor prognosis, with only around 20% of patients aged under 44 years alive at 5 years after their diagnosis. The tumours can occur in patients of all ages including very young children and infants. The current tumour classification system groups these tumours into child-type and adult-type tumours, some of which are very poorly understood. However, we know that some child-type tumours can also occur in adults, and that some adult-type tumours can also occur in children. This project aims to explore the different types of child-like high-grade gliomas that occur across different patient ages. We will gather molecular data from colleagues across the UK and the world to perform different analyses and comparisons to understand more about these tumours at a genetic and microscopic level. We will also attempt to look at the differences in the same types of tumours which occur in patients of different ages. This will be the largest study of its kind, and will show the diversity of child-like HGG subtypes in order to identify potential targets and weaknesses for treatment.