We subsequently clustered the case with 176,857 DNA methylation profiles of tumour samples and control brain tissue samples (including local and external cases submitted through molecularneuropathology.org) and found a larger group of cases that were clustering in close relationship to the initial sample, most often with the highest score for IDH-mutant astrocytoma. This evidence concerns the gene IDH1 and astrocytoma (excluding glioblastoma).