At the same time, we found a significantly lower risk of anaplasia in iLGG (only 30% in iLGG vs. 64% in sLGG), which suggests that gliomas with unfavorable molecular features (like IDH1-wt) grow more quickly, become therefore symptomatic and included partial malignant transformation at an earlier time in the course of the disease. Here, IDH1 is linked to central nervous system cancer.