Conversely, brain tumor diagnostics underwent revisions to incorporate genetic phenotyping (i.e., molecular markers) alongside histopathology when identifying tumor lesions, among which the most notable are: the mutation of isocitrate dehydrogenase (IDH) enzyme, and codeletion of chromosome arms 1p and 19q (1p/19q codeletion) [3]. The gene discussed is IDH2; the disease is brain neoplasm.