IDH1 and central nervous system cancer: Previous molecular subtypes of GBM still have limitations when it comes to improving patient prognosis. The World Health Organization updated its guidelines to reclassify several brain tumor entities, particularly gliomas, considering both morphological and genetic variations and provided the isocitrate dehydrogenase (IDH, an enzyme that catalyzes the conversion of isocitrate to alpha-ketoglutarate in the citric acid cycle in brain tumor) gene mutation subtype [8].