IDH1 and brain neoplasm: Further, with interobserver variability in histological approaches [10,11] as well as landmark discoveries of cardinal molecular alterations including codeletion of chromosomes 1p and 19q (1p/19q-codel) and mutations in isocitrate dehydrogenase (IDH) [12,13], the molecular classification of the brain tumors has now become the norm, represented by the 2016 revised 4th edition and the latest 5th edition of the World Health Organization (WHO) 2021 classification (WHO CNS5) [14,15,16].