Editing Brain tumor (section)

==== By genetics ====
In 2016, the WHO restructured their classifications of some categories of [[glioma]]s to include distinct [[genetic mutations]] that have been useful in differentiating tumor types, prognoses, and treatment responses. Genetic mutations are typically detected via [[immunohistochemistry]], a technique that visualizes the presence or absence of a targeted protein via [[staining]].<ref name=":4" />
* Mutations in [[IDH1]] and [[IDH2]] genes are commonly found in low-grade gliomas
* Loss of both IDH genes combined with loss of [[chromosome]] arms 1p and 19q indicates the tumor is an [[oligodendroglioma]]<ref>{{cite web |url= https://www.lecturio.com/concepts/oligodendroglioma/| title= Oligodendroglioma|website=The Lecturio Medical Concept Library |access-date= 21 August 2021}}</ref>
* Loss of [[P53|TP53]] and [[ATRX]] characterizes [[astrocytoma]]s
* Genes [[Epidermal growth factor receptor|EGFR]], [[Telomerase reverse transcriptase|TERT]], and [[PTEN (gene)|PTEN]], are commonly altered in gliomas and are useful in differentiating tumor grade and biology<ref name=":4" />