IDH1 and glioma: We also observed a substantial proportion of patients with pathogenic constitutional alterations whose tumors were not readily classifiable by RF-based DNA methylation class prediction (31/101, 30.7%), of which most displayed high-grade (13/31, 41.9%) or low-grade (4/31, 12.9%) glioma histology, in line with t-SNE-based DNA methylation class assignment (15/31, 48.4%), including three IDH1-mutant astrocytomas.