After re-analysing the identified samples using the latest (v12.8) version of the Heidelberg brain tumour classifier, most samples (n = 39/51, 76.5%, Online Resource in supplementary Table 1) were successfully allocated to the methylation class of astrocytoma, IDH-mutant; high grade (calibrated score > 0.9). Here, IDH1 is linked to astrocytoma (excluding glioblastoma).