Although our results are similar to previously published data, our study addresses some important issues: integrated diagnosis according to WHO 2021 is essential to define adult-type diffuse glioma IDH-mutant subgroups and to explore key characteristics of each subtype; also, since patients with grade 2 glioma IDH mutant have a median survival of >10 years, our extended follow-up allows reliable data interpretation. The gene discussed is IDH2; the disease is central nervous system cancer.