IDH1 and glioblastoma: Then, the authors carried out a secondary analysis of the TCGA GBM dataset: they found that individuals between 18 and 53 years old presented IDH-mutant GBMs in 15/100 cases (15%), whereas older patients had a significantly lower prevalence of IDH-mutant tumours (2/94 (2.1%) in the 54–63-year-old group, and 1/121 (0–8%) among patients older than 64 years).