Four HGG, one neuroblastoma and one medulloblastoma specimens, which occurred in the context of mismatch repair deficiency and/or mutations in TP53, NF1, H3-3A, and/or BRCA2 indicative of elevated genetic instability, harbored between one and up to 23 mutations in 17 genes (Supplementary Table S11B). Here, TP53 is linked to mismatch repair cancer syndrome 1.