IDH2 and glioma: Based on the world health organization (WHO) criteria, glioma is histopathologically classified into 4 grades; The main glioma types include pilocytic astrocytoma (grade I), anaplastic astrocytomas (grade II), oligodendrogliomas (grade III), and glioblastomas or isocitrate dehydrogenase (IDH) (grade IV) as the most progressive and lethal subtype of glioma with inferior prognoses [22, 23].