In order to assess the impact of the presence of rs55705857-G allele on the clinical progression of tumors, we compared “time to malignant degeneration” (Supplementary Figure 1c) and “overall survival” (Supplementary Figure 1d) of WHO grade-II IDH-mutant 1p/19q co-deleted oligodendrogliomas and IDH-mutant astrocytomas with either the A/G or A/A genotype. This evidence concerns the gene IDH1 and oligodendroglioma.