Updated guidelines in 2021 from the World Health Organization have begun to incorporate genetic mutations into the grading system, allowing for GBM to be classified not only based on its histological appearance, but also as an IDH wild-type, H3 wild-type neoplasm with TERT promoter mutation, amplification of the epidermal growth factor receptor gene, or chromosome copy-number alterations. This evidence concerns the gene EGFR and glioblastoma.