IDH1 and primary brain neoplasm: Molecular markers of brain primary tumors such as O6-methylguanin-DNS-methyltransferase (MGMT), isocitratedehydrogenase-1 (IDH-1), and alpha-thalassemia/mental retardation syndrome X-linked (ATRX) have recently been shown to be correlated with chemotherapy response and prognosis [21].