In the 2021 World Health Organization (WHO) Classification of Central Nervous System (CNS) tumors, diffuse gliomas are classified and graded based on the integrated histo-molecular diagnosis.1 Among gliomas isocitrate dehydrogenase (IDH) 1/2-mutant, the distinction between grade 2 and grade 3 remains governed by morphologic features (including mitotic activity). Here, IDH3A is linked to central nervous system cancer.